Outbreak Report Outbreak of Salmonella Agona phage type 40 ...

Outbreak ReportOutbreak of Salmonella Agona phagetype 40 associated with the Street SpiceFestival, Newcastle upon TyneFebruary / March 2013ILOG 8168Report date: 19 June 2013Report prepared by: Dr Kirsty Foster, Consultant in Health Protection on behalf of theOutbreak Control TeamThis is the outbreak report of an investigation which was carried out by the former HealthProtection Agency and its partner organisations.

About Public Health EnglandWe work with national and local government, industry and the NHS to protectand improve the nation's health and support healthier choices. We addressinequalities by focusing on removing barriers to good health.We were established on 1 April 2013 to bring together public healthspecialists from more than 70 organisations into a single public health service.Public Health EnglandNorth East Public Health England CentreFloor 2, Citygate, GallowgateNewcastle upon Tyne, NE1 4WH SE1 8UGTel: 0844 225 3550http://www.gov.uk/phe@PHE_uk© Crown Copyright 2013Published June 20132

ContentsSectionPage1 Executive Summary 52 Background 73 Coordination of the response 74 Investigations 115 Results 146 Control measures 247 Legal issues 258 Communications 269 Hypothesis 2810 Conclusion and discussion 2811 Recommendations 3112 Actions taken as a result of this investigation 33Appendices1 – 3 Analytical Studies: methods and results4 Food and Environmental sampling results5 Communications materials3

AcknowledgementsThis was a very large outbreak, which developed rapidly over a short time period; Iwould like to thank all members of the outbreak control team for their hard work onthis complex investigation, in particular the staff of the environmental health teamwho worked tirelessly over the first week of the investigation to contact the hundredsof people reporting illness and gather all necessary information. Thanks also go tothe laboratory staff for the rapid processing of the large number of specimens.Dr Kirsty Foster, Chair of the Outbreak Control TeamAbbreviations and glossaryCHPEHOFWEGBRUGPHPAHPUILOGConsultant in Health ProtectionEnvironmental Health OfficerFood Water and EnvironmentGastrointestinal Bacteria Reference UnitGeneral PractitionerHealth Protection AgencyHealth Protection UnitA reference number used to coordinate the collation ofmicrobiological results from the different laboratories, anymicrobiological specimen that was suspected to beconnected to this outbreak, was given the same ILOGreference number (8168)NCCNewcastle City CouncilOCTOutbreak Control TeamPCRpolymerase chain reactionPCTPrimary Care TrustPFGEPulsed-field gel electrophoresisPT 40 phage type 40sp.Species4

1. Executive Summary1.1. BackgroundThis report describes the investigation of a large outbreak of gastro-intestinalillness in people who attended the Street Spice Festival held in Newcastlebetween 28 February and 2 March 2013.1.2. Coordination of responseThe outbreak investigation was coordinated through a multi-agency outbreakcontrol team (OCT), chaired by a consultant in Health Protection from theNorth East Health Protection Unit, with representatives from Newcastle CityCouncil (Environmental Health / Public Protection and Public Health), NHSNorth of Tyne, the laboratory services of the Health Protection Agency(Newcastle Laboratory, the Food, Water and Environmental Laboratory atYork and Gastrointestinal Bacterial Reference Unit, Colindale) and specialistepidemiology teams from the North East Regional Epidemiology Unit andHPA Colindale.1.3. InvestigationInvestigation of human cases of illness was carried out by the EnvironmentalHealth team of Newcastle City Council, working closely with the HealthProtection Unit.The investigation of food preparation and source of ingredients was led bythe Environmental Health team and involved liaison with environmentalhealth teams in other local authorities involved in the food chain and with theFood Standards Agency.The Health Protection Unit coordinated the on-going communication withcases; communication to the public was jointly coordinated bycommunications teams from Newcastle City Council and the HPA, withNewcastle City Council acting as the first point of contact for media enquiries.Analytical studies (a cohort study of people who attended the event, a followupstudy of cases and a capture-recapture study to estimate the total numberof cases) were undertaken by the Regional Epidemiology team of HPA NorthEast.1.4. Results413 people reported illness to the city council following the event. Cases hadattended the event on any of the three days of the festival suggesting an ongoingsource of infection during the whole event.29 cases of Salmonella were confirmed from people reporting illness; 25 ofthese cases were a newly identified strain of Salmonella, Salmonella Agonaphage type 40. Other cases were Salmonella Hadar (1), Salmonella Cero (1),Salmonella Typhimurium (1) and an untyped Salmonella (1).5

Further investigations using a Polymerase Chain Reaction (PCR) assaysuggested that a number of other faecal organisms, includingenteroaggregative Escherichia coli and Shigella, may have contributed to theburden of illness.Salmonella Agona phage type 40 was isolated from curry leaves (samplesfrom the same batch of leaves used at the event).Pulsed-field gel electrophoresis (PFGE) confirmed that the S.Agona isolatesfrom human and food specimens were indistinguishable.The epidemiological findings from a cohort study supported theenvironmental and microbiological findings. In total 827 people responded tothe survey of which 306 were classified as cases. Risk factors associatedwith illness included eating from one section of a particular stall and eating afood item containing uncooked curry leaves.1.5. ConclusionsThis was a large outbreak of gastro-intestinal illness, with Salmonella AgonaPT 40 confirmed in 25 cases and also isolated from a food ingredient used atthe event.Findings from further laboratory analysis suggest that other faecal organisms,including entero-aggregative Escherichia coli and Shigella, may also havecontributed to the burden of illness.The OCT concluded that the use of uncooked curry leaves, which werecontaminated with Salmonella Agona PT40, was the mechanism oftransmission of infection.After consideration of the findings of the investigation, Newcastle City Councildecided not to take formal action in this case. This decision, based on thecouncil‟s enforcement policy, took into account the lack of clear, officialadvice about the use of curry leaves and the overall good standards of foodhygiene at the festival.6

2. BackgroundThe Street Spice Festival (a charity event) was held in Times Square, Newcastleupon Tyne between 28 February (Thursday) and 2 March (Saturday) 2013. Theevent had been well publicised in local print and social media and drew visitorsfrom across the North East.3. Coordination of response3.1. How the incident came to lightThe organiser of the event contacted the Environmental Health (EH)department at Newcastle City Council (NCC) first thing on Monday 4 Marchfollowing reports of illness made to him (directly and via Twitter and othersocial media sites) over the weekend.People also contacted the EH department directly on Monday 4 March.The EH team contacted the North East Health Protection Unit (NEHPU) on 4March; on the first day the number of reports of illness was in single figuresand it was agreed to collect as much information as possible from thoseparties. However as numbers increased during the day, it was agreed that anoutbreak control meeting was required and this was arranged for 6 March.The EH team continued to collect information and stool samples fromaffected visitors to the event and to make contact with the event organiserready to inform the risk assessment discussion at the OCT meeting.3.2. SettingThe event was held in a large marquee (40 x 15 m) in Times Square incentral Newcastle upon Tyne and was attended by 10 – 12,000 people overthe three days.There were 18 hot food stalls and seven cold food / drink stalls and producetraders present serving a variety of foods; most of the stalls were present forall three days and most were from food premises within the North East ofEnglandThe event was organised by the owners of Sachins restaurant, Newcastleupon Tyne.The event ran for the following times:Thursday 28 February: 2 – 10pm (although 2 – 4pm was VIP only)Friday 1 March: 4 – 10pmSaturday 2 March: 12 – 10pm7

3.3. Outbreak Control TeamA multi-agency outbreak control team (OCT) was convened with the followingmembers.NameDr Kirsty Foster (Chair) (x)Jon Lawler (x)Emma Thody (x)Karen Lloyd (x)Dr Russell GortonDr Alison WaldramDaniel GardinerStephen SavageVivienne Air (x)Paula Davis (x)Tracy SweetColette CasselyNigel Whitefield (x)James Plater (x)Dr John PiggottJohn HarfordJennifer CollinsMichelle PayneDr Brendan PayneDr Kathie GrantDr Elizabeth de PinnaDr Chris LaneOrganisationNorth East Health Protection UnitNorth East Health Protection UnitHealth Protection Agency, North EastHealth Protection Agency, North EastRegional Epidemiology Unit, HPANorth EastRegional Epidemiology Unit, HPANorth EastRegional Epidemiology Unit, HPANorth EastRegulatory Services and PublicProtection Division, Newcastle CityCouncilRegulatory Services and PublicProtection Division, Newcastle CityCouncilRegulatory Services and PublicProtection Division, Newcastle CityCouncilRegulatory Services and PublicProtection Division, Newcastle CityCouncilRegulatory Services and PublicProtection Division, Newcastle CityCouncilPress Office, Newcastle City CouncilPress Office, Newcastle City CouncilHPA Food, Water and Environmentlaboratory (York)HPA Food, Water and Environmentlaboratory (York)Newcastle upon Tyne Hospitals TrustNewcastle upon Tyne Hospitals TrustHealth Protection Agency laboratory,NewcastleGastrointestinal Bacteria ReferenceUnit, HPA ColindaleGastrointestinal Bacteria ReferenceUnit, HPA ColindaleGastrointestinal, Enteric andZoonotic Department, HPA Colindale8

8 March Web-based cohort study launched (for all attendees ill and not ill)11 March Third OCT meetingNumber reporting illness = 38214 confirmed cases of SalmonellaPreliminary results from analytical study show associationbetween illness and food from Sachins stall and with the SouthIndian food items13 March Fourth OCT meetingNumber reporting illness = >40020 cases of confirmed SalmonellaPresumptive typing from Colindale – Salmonella AgonaSalmonella O4, g isolated from curry leaves used in coconutchutneyFindings of food samples reported to FSA by NCC and HPAAnalytical study analysis showed shows strongest associationbetween illness with coconut chutney14 March NCC submitted incident report to FSA15 March First separate Communications planning sub-group meetingActions regarding communication to people reporting illness19 March Fifth OCT meetingNumbers reporting illness = >40028 confirmed cases of SalmonellaFurther typed specimens identified as new strain of SalmonellaAgona phage type (PT) 4019 March Alert sent to European Centre for Disease Control (ECDC)Epidemic Intelligence Information System (EPIS)20 March Second Communications planning group meeting20 / 21 March Update on investigation sent to all people who had reportedillness to EH department or reported illness via the on-linesurvey.27 March Sixth OCT meetingNumbers reporting illness = 41329 confirmed Salmonella cases28 March Case follow-up survey launched12 April Seventh OCT meetingNumber reporting illness = 41329 confirmed cases of SalmonellaOf which 25 cases Salmonella Agona PT40Further isolates from curry leaves identified as Salmonella AgonaOutbreak investigation closed.NCC work on possible enforcement action continues.10

29 April Case follow-up survey closed10 May Further follow-up of cases with continuing illness4. Investigations4.1. Epidemiological4.1.1. Case definitions usedThe OCT agreed the following case definitions:Confirmed case: A person with laboratory confirmed Salmonella (O4g)who attended the Street Spice event between 28 February and 2 MarchProbable case: A person who reports diarrhoea + two other symptomsfrom abdominal pain / cramps, nausea, vomiting, fever starting afterattendance at the Street Spice Festival between 28 February and 2March.During the investigation, these case definitions were refined as furtherinformation about cases and symptoms was gathered.Final case definition: A person with diarrhoea who became ill between 12hours and 5 days after attending the Street Spice event.4.1.2. Case findingInitially people self-reported illness to NCC EH department; these tendedto be groups of friends or families.A smaller number of cases of illness were reported to the HPU by severalroutes, including self-report, GP report or following routine investigationof a Salmonella case. NCC EH department were provided with details ofall these cases.On 6 March 2013, a letter was sent to GPs asking them to notify anycases of illness reporting attendance at Street Spice Festival (and collecta specimen under ILOG number).As awareness of the outbreak spread, consultant microbiologists at localNHS laboratories were asked to alert the HPU of any positive Salmonellaresults where clinical details on the specimen mentioned “Street Spice”.Information was also shared between attendees on social media sites(Twitter and Facebook) advising people to contact EH department; insome cases this occurred before the formal communication from theOCT.4.1.3. ExposuresStaff from the NCC EH team collected food histories / exposures frompeople reporting illness. After the initial 20 – 30 cases, it became clearthat attendance at the Street Spice Festival was the common factor in11

those reporting illness, so to make information collection / caseinterviewing manageable the investigation focussed on attendance andfood eaten at the festival.As described above, there were many stalls serving a range of foods;details of stalls visited and foods eaten were collected and recorded.4.1.4. Analytical studiesAt the first OCT meeting, the group agreed that a cohort study should beundertaken; it was agreed to use a web-based study to capture the largenumber of attendees and to publicise this through social media(Facebook and Twitter) as well as regional television and print media.During the course of the investigation, when it was apparent that caseswere reporting prolonged symptoms, the OCT agreed that a follow-upstudy of cases should also be undertaken.Of the 592 cases reported by any method, 527 were sent a link to thecase follow-up survey by email if available, otherwise by post.Details of the survey were circulated on 28 March, with a closing date forresponses of 22 April.Cases who reported on-going illness in the case follow-up study were recontactedon 10 May to determine the final length of symptoms / end ofillness.As there were different sources of information on case numbers, acapture-recapture analysis was also undertaken to estimate the truenumber of people affected.See Appendices 1-3 for more detailed description of the methodologyused in the analytical studies4.1.5. Data managementCase details were recorded on a spreadsheet held by the NCC EH team.Laboratory results were managed by the Health Protection Unit (HPU) asresults came from both the HPA Newcastle laboratory, based atNewcastle upon Tyne Hopsitals, and other NHS laboratories across theregion.The EH and HPU teams ensured that the two lists of cases (reportedillness and laboratory-confirmed infection) were reconciled and deduplicated,and that all appropriate investigations and follow-up wereundertaken.4.2. Microbiological4.2.1. Sample collectionInitially members of the EH team at NCC collected faecal samples frompeople reporting illness and transported the samples to the laboratory.However, as the numbers of people reporting illness rapidly increased,this arrangement became impractical and people were advised to submitspecimens via their GP; this advice was complemented by the alert to allGPs in the region asking them to collect samples and submit them using12

the outbreak ILOG number so that they would be processed at the HPAlaboratory and results easily collated.4.2.2. Laboratories usedArrangements were made for specimens to be processed at the HPAlaboratory, Newcastle (Freeman Hospital) using the ILOG number toidentify the specimens as part of the outbreak.In accordance with standard practice at HPA and NHS laboratories,isolates from all positive cultures were sent to the GastrointestinalBacteria Reference Unit at HPA Colindale for further typing.4.2.3. Microbiological testingSamples were tested for standard bacterial pathogens (Salmonella,Campylobacter, E coli O157, Shigella), Cryptosporidium, Norovirus,Clostridium perfringens and Bacillus cereus.As the information about likely organism and food source evolved andnegative results from certain tests were received, the testing panel wasreduced to bacterial pathogens only.Because there were a relatively low number of confirmed Salmonellainfections on the early specimens analysed at the HPA laboratory, it wasagreed that specimens would be re-cultured on to alternative Salmonellaselective media along with a repeat Xylose lysine deoxycholate (XLD)culture plate. (The alternative media were Brilliance Salmonella (Oxoid),ASAP (a chromogenic Salmonella medium from AES); all repeat testingof specimens were assessed both pre and post-enrichment culture).Subsequent specimens were cultured on both media simultaneously.A sub-set of faecal samples (positive and negative by culture) from theHPA laboratory were sent to the Public Health Laboratory, London formultiplex PCR testing for a range of gastro-intestinal bacterial pathogens.4.3. Environmental4.3.1. InspectionEnvironmental Health Officers from NCC contacted the organiser of theevent on 4 March and gathered information about the event and thepremises used.On 5 March, they visited the kitchen at Sachins restaurant which is wherethe implicated foods had been prepared.4.3.2. Food preparationStaff from the EH team gathered detailed information on the foodsprepared at the implicated stall; information was gathered from therestaurant staff involved in food preparation prior to the event and thestaff involved in cooking and serving foods at the stall.Details of ingredients, exactly how they were handled, prepared andserved were gathered during the investigation.13

4.3.3. Food and environmental samplingSamples of any remaining foods or ingredients which were used by theimplicated stall were collected.Environmental samples, including swabs of food preparation and contactsurfaces, equipment and containers, were collected from the restaurantkitchen. As the event had finished and the stalls had been dismantled bythe time illness was reported it was not possible to collect samples fromthe areas where food was served to customers.The EH team also visited the two local suppliers to collect samples ofadditional ingredients. These were foods known to have been used in thepreparation of implicated dishes. As there were no foods from the samebatches as those used at the festival, samples from other batch codeswere taken for comparison.Foods collected over several visits to the restaurant and suppliers werecoconut milk powder, desiccated coconut, asafoetida, whole green chilli,fresh coriander, birdseye whole green chilli, fresh ginger, curry leaves*,urad dall (black lentils), dried basmati rice, dried long grain rice, toor dall,chilli powder, chicken tikka, cooked dhal, garam masala, cooked rice.Environmental samples were collected from wash hand basin tap,blender blade, onion basket, fridge handle, food containers, preparationbench and a shelf above preperation bench.All food and environmental samples were sent to the HPA Food, Waterand Environmental laboratory at York.* the curry leaves were originally recorded as “dried” but it was confirmedon later checking that fresh leaves had been used and sampled.5. Results and interpretation5.1. EpidemiologicalThe reporting of illness and identification of cases of confirmed infectionassociated with this outbreak was complex. As described in the earliersections of the report, cases initially contacted the EH department at NCC toreport illness and these cases form the majority of cases included in thisreport.However, cases also came to light through a number of other sourcesincluding direct reporting to the Health Protection Unit, through confirmedSalmonella (O4,g) detected in local NHS laboratories not tested at the HPAlaboratory and through illness reported on the on-line cohort study.Findings from all of these sources have been used in the descriptiveepidemiology of this outbreak.5.2. Descriptive epidemiologyA total of 413 people reported illness (gastro-intestinal symptoms) to the NCC14

EH department following attendance at the Street Spice Festival.These reports of illness were either made directly to the department or weremade during follow-up of a positive Salmonella O4,g laboratory result.Further cases of illness were received through the on-line survey of festivalattenders, making a total number reporting illness of 592.Age groupFrom the entire dataset (EH list, laboratory list and illness reported on survey)Table 1: People reporting illness following attendance at Street Spice FestivalNGenderMale Female Unknown% byagegroup% bygenderN% byagegroup% bygenderN% byagegroup% bygenderNTotal% byagegroup% bygender

Table 2: Symptoms and duration of illness from case follow-up studyMean Median DurationSymptom Number Percentageduration duration rangeDiarrhoea 351 100 12.3 11 1-49*still ill 14 - 32.4 27 25-49*not still ill 337 - 11.4 11 1-43Abdominal pain 320 91 9.2 7 1-47*still ill 11 - 33.1 34 14-47*not still ill 308 - 8.3 7 1-34Nausea 203 58 4.6 3 1-28Fever 155 44 2.8 2 1-14Vomiting 64 18 1.7 1 1-65.2.5. Hospital admissionsInformation about hospital admissions was difficult to verify with such alarge number of people affected; in the case follow-up study two peoplereported hospital admission (0.5% hospitalisation rate), but theseadmissions were short-lived. Another six people visited hospital withsymptoms but were not admitted.5.2.6. Foods eatenThe EH team identified that a wide range of foods were served acrossthe event, however from early on in the investigation, it was clear that aparticular stall and food items were reported in high numbers by peoplewho were ill.The foods most frequently reported as eaten were the “South Indian”foods served from the Dosa Hut section of the Sachins stall, and anassociation between illness and consuming these foods was found in thecohort study with no associations with food from other stalls.Investigation of food preparation therefore concentrated on foods fromthe Dosa Hut section of the Sachins stall. The food in the Dosa Hutsection was prepared by a guest chef invited to the event by theorganiser.Approximately 900 – 1000 portions of these foods were served over thethree days of the festival.5.2.7. Food preparation including findings of inspectionThe dishes served at the Dosa Hut section of the Sachins stall, whichwere all vegetarian, were a dosa, an uttaphum and a vada.Each dish was accompanied by coconut chutney and a lentil sambasauce unless specifically requested not to by the customer.17

Information was gathered about the preparation of the foods used at thefestival by taking statements from all of the chefs and kitchen porters whoworked in the kitchen at the time. They informed officers that thepreparation of these foods involved several stages:A batter was made prior to the event in the restaurant kitchen for thedosa and uttaphum; this involved soaking the dried lentils and riceovernight at room temperature, the mixture was then blended thefollowing day to make the batter.The dosa filling consisted of potato, onion, ginger, curry leaves andspices which had been cooked at the restaurant, blast chilled and thenreheated on site and hot held.The uttaphum topping which consisted of onions, peppers and corianderwas cooked to order on site.The vada contained chickpeas, spinach and spices and was prepared,deep fried, blast chilled in Sachins kitchen and was reheated to order onsite.The samba consisted of lentils, onions, tomatoes and spices which wereslow cooked then blast chilled in Sachins kitchen. Then reheated on siteand then hot held.The coconut chutney was made by liquidising together desiccatedcoconut, coconut milk, ginger, chilli, fresh curry leaves, coriander, salt,green chillies and water.The curry leaves were purchased locally and were stripped from thestalks by two members of the restaurant staff on 27 February; up to 7bags of curry leaves were prepared in this way. Leaves were then put alltogether in a larger plastic bag, placed in the chiller, to be used by thechef in preparation of the chutney (see section 6 for more detail on foodchain supply of curry leaves).Batches of chutney were made on each day of the event.The leaves were taken out of the larger bag and washed by the chefduring the preparation of the chutney by holding them under cold runningwater. They were then added into the chutney mixture whole and groundup using a stick blender.The leaves were not in contact with any other surfaces in the kitchenduring this preparation and a designated area of the kitchen was used.Once made the chutney was stored in containers which were coveredand stored in the fridge at Sachins kitchen before being transported tothe festival site.A large fridge was available at the site which was used for the storage ofchutney. A quantity of chutney was kept in a small serving bowl on the18

stall.5.2.8. Analytical studies(see Appendices 1 - 3 for further details of all analytical studies)5.2.8.1. Cohort study.The study was undertaken using a web-based questionnaire.Attendees at the Street Spice Festival were invited to respond tomessages distributed via Twitter, a Facebook group and released ina press statement.827 completed responses were received; of these, 347 reportedgastro-intestinal symptoms following the event and 306 met the casedefinition for the analytical study.Univariate analysis found significant association between illness andeating food from the Sachins stall (Risk Ratio (RR) = 8.59, 95% CI6.08 – 12.14) and eating the South Indian foods (RR = 7.77, 95% CI6.10 – 9.91). 89% of the cases reported eating South Indian foods.There were no associations between being ill and any of the otherstalls.Looking at specific food items served at the Sachins stall, there weresignificant associations between illness and eating several fooditems including coconut chutney (RR = 4.39, 95% CI 3.73 – 5.17),dosa (RR = 4.29, 95% CI 3.62 – 5.08), uttaphum (RR = 2.73, 95%CI 2.40 – 3.11) and vada (RR = 2.65, 95% CI 2.30 – 3.05).On stratified analyses, associations with the standard restaurantfoods (i.e. non-South Indian foods) were reduced (univariate RR1.69, adjusted RR 1.23) suggesting that confounding between thedifferent foods had raised the univariate risk ratios. When individualSachins food items were stratified by coconut chutney theassociations were similarly reduced.The findings of the cohort study are that consuming South Indianfoods from the Dosa Hut section of the Sachins stall was statisticallysignificantly associated with illness and explained 89% of the cases.This is very strongly suggestive that this association was causal.The strongest association with a single food item was with coconutchutney, which was served as a side dish rather than as a menuitem in itself and as such is likely to have not been reported as anexposure by all people consuming it. This is the most likelyexplanation for the RR for coconut chutney being lower than forSouth Indian foods as a whole, and for some other foods remainingsignificantly associated with illness after stratification by reportedcoconut chutney consumption.However another possible reason for this is cross contamination19

etween the items, such that some portions of other foods becamecontaminated and caused some of the illnesses. The study could notdistinguish between these possibilities, but nevertheless providesstrong evidence that the coconut chutney was the main vehicle ofinfection.Further details of the results of the cohort study are contained inAppendix 1.5.2.8.2. Case follow-up study527 people who reported illness were contacted to complete thecase follow-up study, of which 374 responded (71% response rate);351 respondents met the updated case definition (person withdiarrhoea who became ill between 12 hours and 5 days afterattending Street Spice) and were included in the analysis.Symptoms and duration of illness are reported in section 5.2.4.Of the 351 cases who completed the survey:64.7% contacted some form of healthcare service because of theirsymptoms; most commonly this was their GP (40%).The cases that attended their GP visited between one and five times(mean number of visits: 1.5).Cases visited or contacted between one and five different healthcare/ public health services.35% reported that they had contacted the EH department atNewcastle City Council about their illness.59% had to take time off work due to their symptoms; the mean timeoff work was 4.9 days (range 1 – 35 days), the total number ofworking days lost was 995.43% reported submitting a stool specimen. The mean number ofspecimens submitted was 1.2, with a range of one to six samples.Further details of the case follow-up study are contained in Appendix2.5.2.8.3. Capture-recapture analysisUsing the three sources of information about cases (people reportingillness to EH department, laboratory results of people not known tothe EH department and people reporting illness via the on-linesurvey for the cohort study) a capture-recapture analysis wasundertaken to estimate the true size of the outbreak.The estimated total number of people ill was 926 (95% CI: 628 –20

1224). The upper limit of the confidence intervals exceeded the totalnumber of servings of the suspected food. This may reflect theimprecision of the estimate and resulting wide confidence intervals,though inaccuracies in the reported number of servings, sharing ofsingle portions between customers and cross contamination mightall be reasons that more people could be ill than reported portionsserved.Further details of the capture-recapture study are contained inAppendix 3.5.3. Microbiological / laboratory results5.3.1. Human isolates5.3.1.1. Microbiological culture and phage typing110 faecal specimens were submitted to the HPA laboratory,Newcastle under the ILOG outbreak number.29 samples were positive on culture for Salmonella.Of these, 25 were Salmonella Agona phage type 40.There was 1 case of Salmonella Cero, 1 case of Salmonella Hadar,1 case of Salmonella Typhimurium and 1 Salmonella sp. which wasuntyped.21 of the confirmed Salmonella cases were identified at theNewcastle HPA laboratory, and 8 at a number of local NHSlaboratories in the North East region.It is not possible to say how many specimens were submitted toother laboratories, but the case follow-up study suggested that atleast 151 people submitted specimens.5.3.1.2. PCR testingMolecular (PCR) testing identifies genetic material from microorganisms;by selecting DNA fragments with specific characteristicsof organisms, PCR testing can be used for rapid identification ofindividual species in clinical specimens.The assay used in this outbreak tested for Salmonella,Campylobacter (coli and jejuni), verocytotoxigenic E. coli (VT toxin 1and VT toxin 2), Shigella and Entero-aggregative E. coli.The PCR multiplex assay is not a standard clinical diagnostictechnique and was used in this outbreak as an adjunct to standardlaboratory investigations in an attempt to explain the low number of21

laboratory confirmed infections and clinical picture of prolonged andsevere symptoms in the early stages of the investigation.Eighty eight faecal samples, where there was sufficient sample leftafter standard laboratory investigations were completed at the HPAlaboratory Newcastle, were sent to the Public Health Laboratory,Barts NHS Trust, London for PCR testing.The samples submitted for PCR testing included some which hadbeen positive and some which had been negative for Salmonella bystandard culture methods at the HPA laboratory.Results from the PCR testing were consistent with people havingbeen exposed to other faecal pathogens.Entero-aggregative E. coli, an organism commonly associated withtravellers‟ diarrhoea was detected by PCR in 80% of the samples.The symptoms of entero-aggregative E. coli infection can beprolonged and include abdominal pain and diarrhoea, which wouldhave been consistent with the pattern of illness described by thoseaffected in this outbreak.Shigella was detected by PCR in 39% of the samples submitted.The symptoms of Shigella include diarrhoea, nausea, fever andabdominal cramps.These findings, although not from a standard clinical diagnostic test,suggest that a range of faecal organisms contributed to the burdenof illness associated with this event, with the most likely sourcebeing from a contaminated food item.E. coli detected on food samples including the curry leaves wasidentified by standard culture methods and it is not standard practiceto undertake further typing on E. coli identified in food specimens.Whilst the culture used for food samples would have detectedentero-aggregative E. coli, it is not possible to state definitively thatthis was present on the food items.5.3.2. Food and environmental5.3.2.1. Environmental swabsAll environmental swabs from the restaurant kitchens were negativefor Salmonella.5.3.2.2. Food samples / list of resultsIsolates of Bacillus detected above 10 5 cfu/g on the Rajah GaramMasala and Dahl and the Salmonella isolates from the curry leaveswere sent to the GBRU at HPA Colindale for further typing.Salmonella O4, g, E. coli and Enterobacteriaceae were isolated from22

the curry leaves obtained from the restaurant and known to havebeen from the batch used in the coconut chutney.Further typing of the Salmonella isolates, undertaken at the HPAlaboratory at Colindale, identified Salmonella Agona PT 40.A second batch of curry leaves from the same local supplied testednegative for Salmonella.Other food samples (fresh ginger, chilli and coriander) had highlevels of Enterobacteriaceae.See Appendix 4 for full table of food and environmental results.5.3.3. Pulsed-Field Gel Electrophoresis analysis of human and foodsamplesPulsed-field gel electrophoresis (PFGE) was carried out on a sample ofhuman S. Agona isolates and the S. Agona isolates from the curryleaves. The profiles were analysed using BioNumerics software (version6.10; Applied Maths, Sint-Martens-Latem, Belgium).Figure 2: Pulsed-field gel electrophoresisRepresentative pulsed-field gel electrophoresis profiles of SalmonellaAgona PT40 isolates from patient and curry leaf samples shows them tobe indistinguishable.5.4. Summary of resultsAs outlined above, the complex investigation of this large outbreak foundstrong evidence linking the consumption of a dish containing a contaminatedfood ingredient with gastro-intestinal illness.Microbiological findings of a newly identified strain of Salmonella (SalmonellaAgona phage type 40) in human samples and from the food samples (the23

fresh curry leaves from the batch used in food served at the event) weresupported by very strong epidemiological evidence from a large cohort studywhich identified coconut chutney made with the uncooked curry leaves ashaving the strongest association with illness.Further molecular (PCR) investigations, undertaken to explore why there wassuch a large burden of illness with a relatively small number of confirmedcases of Salmonella, found that 80% of samples tested were positive forentero-aggregative E.coli and 39% were positive for Shigella, both organismsassociated with travellers‟ diarrhoea and whose clinical features match withthose described by many of the people reporting illness in this outbreak.There is evidence from standard tests that E.coli was present on the leavesin addition to Salmonella, but we were not able to test food samples from thefestival using molecular techniques and have no evidence as to whether ornot this was the entero-aggregative E.coli strain.Although the PCR test is newly developed and is not fully validated for use asa routine clinical diagnostic test, the findings from its use in this outbreaksuggest an explanation for the burden of illness experienced; that is that theleaves may have been contaminated, and the reported illness caused, bymore than one organism.6. Control measuresThe OCT identified three areas of public health riskAn infected food handlerAll staff involved in preparation and serving of the food at the South East Indianfood stall were interviewed and submitted faecal specimens.There was no reported diarrhoeal illness in the staff and all faecal specimenswere negative for Salmonella.A contaminated food item / ingredient, with potential for continuing presence inthe food chainAs described above, detailed information about the preparation of the food itemswas collected by members of the EH team.Following the identification of Salmonella on the curry leaves used in the coconutchutney, further investigation and control measures were undertaken.EHOs from Newcastle City Council identified that the Newcastle retailer, wherethe leaves had been purchased, got his supplies from a wholesaler in Yorkshire.Newcastle EHOs worked with EH colleagues in Yorkshire to further investigatethe supply chain of the curry leaves.The importer of the curry leaves in London and the exporter (in Pakistan) werecontacted directly by NCC EHOs. The importer confirmed that the curry leaveswere received as a wrapped product in a cardboard box imported via Heathrowand no further treatment or labelling was carried out. The exporter confirmed that24

the Airway bill is used as a means of traceability. They consider the product tobe raw although it is not labelled to this effect. The product did not undergo anymicrobiological testing but they did provide a microbiological test of water used towash the curry leaves in Pakistan.NCC EHOs then liaised with Port Health at the port of entry to arrange for furtherleaves to be collected at port of entry and to be sent to the FWE lab in London foranalysis to establish whether the contamination of curry leaves from this supplierwas an on-going problem / public health risk. Samples collected on 11 April 2013were negative on culture for Salmonella.At a local level, EHOs ensured that the use of raw curry leaves was not usualpractice in the restaurant where the foods for the festival had been prepared. Noon-going risk from the use of this ingredient, for example by cross contamination,was identified in the restaurant. The OCT therefore concluded that there was notan on-going local public health risk.A food incident report was sent to the Food Standards Agency (FSA) with detailsabout the outbreak and in particular the likely source of the infection and detailsof the importer of the curry leaves. A number of updates were given to theincidents branch and to the regional FSA team as the investigation continued.There was discussion between the OCT and the FSA about whether specificadvice about the use of curry leaves needed to be issued. The advice from theFSA was that whilst specific advice did not exist regarding curry leaves, standardpractice regarding storage and washing leaves would be an option.Given that this was generic food-handling advice that should already be availableto food business operators and the public, the OCT did not consider it necessaryto issue specific advice during the outbreak.Secondary transmission of infectionAdvice was given to cases about the need for careful attention to hand / personalhygiene whilst they had diarrhoeal illness. Cases were also advised to stay offwork / college until 48 hours symptom-free.The case follow-up survey asked about illness in household or other contacts(after the case‟s onset), 17 household cases were reported.There were also two cases that fell outside of the case definition, because thedate of onset was later than the maximum incubation period used. Reasons fortheir illness could have been unreported or asymptomatic primary cases,genuinely longer incubation period or unrelated illness.7. Legal issuesThe investigation focussed on the collection of evidence related to:Regulation (EC) No 178/2002 Article 14 which states Food should not beplaced on the market if it is unsafe, (this includes contamination)andEC Regulation 852/2004 Article 5 which states Food business operators shallput in place, implement and maintain a permanent procedure or proceduresbased on the HACCP principles.25

Evidence to support or refute a due diligence defence in accordance with the Food Safety Act1980 was also considered.After consideration of the findings of the investigation, NCC decided not to takeformal action in this case. This decision, based on the council‟s enforcement policy,took into account the lack of clear, official advice about the use of curry leaves andthe overall good standards of food hygiene at the festival.8. Communications (see Appendix 5).8.1. To the public8.1.1. To people reporting illnessPeople who reported illness to the EH team at NCC or to the HPU weregiven verbal advice about preventing transmission of illness and advisedto seek medical advice if their symptoms worsened.During the course of the investigation, a number of people who submittedsamples had a “negative” stool specimen (i.e. culture did not detectSalmonella or any other pathogen) but still had symptoms and met thecase definition used by the OCT. These people were provided withinformation about the investigation and the interpretation of “negative”results.An update was sent to all people who had reported illness (by post andemail) on 21 and 22 March 2013 providing an update on the investigationand findings.As noted above, the OCT also carried out a follow-up study of peoplewho reported illness. Cases were contacted by email or letter to invitetheir participation in the study.Letters were also sent to the people whose stool specimens werepositive for E.coli and / or Shigella on PCR testing.8.1.2. To people who attended the eventInformation about illness in people who attended the event was alreadycirculating on social media sites linked to the event before the formalOCT investigation started.The OCT explored the amount of social media followers for the varioussites and found:- Street Spice Festival Twitter account had 1851 followers- HPA Twitter account had 6498- Newcastle City Council Twitter account had 17228 followers- Street Spice Facebook group had 734 “likes”- HPA Facebook group had 779 “likes”The social media sites were used to publicise the OCT investigation andto invite people who had attended the event to participate in the cohortstudy. The sites were also used to direct people to the press statementsabout the investigation and early findings which were posted on the26

Newcastle City Council and HPA North East websites.8.1.3. To the wider publicInformation about the outbreak and the OCT investigation was providedin a series of proactive press releases and interviews on local newsprogrammes. The Director of Regulatory Services for Newcastle CityCouncil acted as the spokesperson for the OCT on broadcast interviews.8.1.4. Survey of attendeesAs noted above, a cohort study was undertaken of people who attendedthe event. The information, and the link to the study questionnaire, aboutthis study was included in early press statements (8 March) and wasposted on the Street Spice website and HPA and NCC twitter accounts;the information was also re-tweeted by a number of participants.8.1.5. Press statements and media reportingNewcastle City Council led the multi-agency communications responseon behalf of the OCT and acted as the main point of contact for pressenquiries.A reactive media statement, prepared on the 6 March, was issued to theBBC local news team.Further press statements were issued on 7 March, 8 March, 11 March,15 March and 21 March.Request for information from solicitors known to be acting on behalf ofsome of the cases, the press and the BBC were received.Holding statements were issued while the investigations were on-going.8.2. Professional updates8.2.1. LaboratoriesWhen it became apparent that people who were ill following the eventwere attending their GP and submitting stool samples via NHS labs, analert about the outbreak investigation was sent to all consultantmicrobiologists on 7 March asking them to report any clinical sampleswhere “Street Spice” mentioned in the clinical details.On 8 March 2013, an update was sent to the same group when furthertyping information (Salmonella O4, g) was known asking them to referany locally detected cases to the HPU.8.2.2. General practitionersAn alert was sent to all General Practitioners in the North East on 6March 2013 outlining the OCT investigation process and asking them tocollect stool samples from any patient reporting diarrhoeal illnessfollowing attendance at the Street Spice festival. GPs were asked to usethe ILOG number on specimens so that samples could be transported toand processed at the HPA laboratory, Newcastle.8.2.3. HPA / PHEBriefings on the outbreak investigation were sent to appropriate teams /27

directorates within the Health Protection Agency / Public Health England.8.2.4. European updatesIn line with requirements 1 , a report on the outbreak investigation was sentto the European Surveillance to enable any linked cases detected inEurope to be considered.There were no reports of illness associated with attendance at thefestival, and no further cases of S. Agona PT40 from European partneragencies.9. HypothesisThe hypothesis of the OCT is that contaminated curry leaves, which were useduncooked in a chutney, were the source of illness in people attending the StreetSpice Festival.The hypothesis is supported by the epidemiological and microbiological findingsof this investigation from both human and food samples.The composition of the chutney may have increased the chances of Salmonellaand other organisms surviving and causing illness as the fatty nature (desiccatedcoconut and coconut milk) of the chutney would have provided an ideal growthmedium for Salmonellae introduced from the contaminated curry leaves. Batchesof the chutney were held in a chiller onsite but it is possible that the chutneydecanted into smaller containers for service may have been held for some time atambient temperature on the stall which could have increased the growth rate ofthe bacteria.10. Discussion and conclusionsThe OCT concluded that this large outbreak of gastro-intestinal illness, withcases of confirmed Salmonella Agona PT40, was caused by the use of uncookedfresh curry leaves, which were contaminated with the same strain of Salmonella.A review of outbreaks reported to the HPA‟s electronic Foodborne and nonfoodbornegastrointestinal Outbreak Surveillance System (eFOSS) 2 found thatthis has been one of the largest food-borne outbreaks in the UK since 1992, andwas the largest UK outbreak where herbs or spices had been identified as thesuspected source of infection.1 All member States are requested to submit information on outbreaks of GI infections, particularly wherethere may be potential for foreign cases or the food vehicle is considered a potential risk through import toother EU States. This then allows other member states the opportunity to check whether or not they havecases that could be attributed to the same vehicle (or event where travel is included). Whilst this is notmandatory, the benefits of reporting such events allow for better epidemiology across Europe.2 HPA electronic Foodborne and non-foodborne gastrointestinal Outbreak Surveillance System (eFOSS).The Health Protection Agency has operated a system of surveillance for general outbreaks of infectiousintestinal disease (IID) in England and Wales since 1992, which includes foodborne and non-foodbornegastrointestinal outbreaks.28

The organismThe Salmonella genus is composed of two species; S. enterica and S. bongori .Salmonella enterica, which is a leading cause of gastroenteritis, is subdivided intohundreds of serovars. Salmonella Agona is one of the serovars of S. enterica. S.Agona is a non-typhoidal Salmonella.Infection with Salmonella bacteria can cause gastroenteritis (diarrhoea,abdominal cramps, and fever), which is usually a self-limiting, uncomplicateddisease lasting three to seven days. However, Salmonella infection can be moreserious causing dehydration, blood-poisoning (septicaemia) and abscesses. Theelderly, very young or immunocompromised are more prone to serious illness orcomplications. Salmonella infection is usually acquired by eating food, especiallyundercooked poultry, meat or eggs. Ready-to-eat products such as sandwichesor other products can become contaminated with Salmonella bacteria and causeinfection. Salmonellae can also be transmitted directly from person to person viathe faecal-oral route, from an infected person to a foodstuff or from an infectedanimal to a person.The symptoms reported by cases in this outbreak were unusual in that diarrhoeaand abdominal pain persisted for longer than is commonly associated withSalmonella infection.Although Salmonella Agona has been previously identified, the specific phagetype, Salmonella Agona PT40 has not been recognised before in either food orhuman samples.Findings from the molecular (PCR) testing of specimens suggest that othergastro-intestinal pathogens, including entero-aggregative E. coli and Shigella,may have contributed to the burden of illness in people who attended the event.The vehicle of transmissionDried and fresh herbs and spices are known to be potential sources ofSalmonella and other organisms, and have been reported in the scientificliterature as the source of infection in a number of outbreaks.Sampling studies have identified contamination of curry leaves with differentstrains of Salmonella, but the strain identified in this outbreak had not beendetected before.The HPA carried out a food survey of fresh herbs in 2007, involving 3,760specimens. Of these, 21 specimens were of Curry leaves, 2 of which werepositive for Salmonella (#1 – S.Newport + S.Virchow PT 8, #2 – S.Virchow PT21). Of the 21 specimens, details of country of origin were available for 10, (India8, Cyprus 1, UK 1), none were from Pakistan 3 .It is possible that curry leaves were contaminated with other strains of Salmonellaas well as other faecal organisms. Salmonella Hadar and Salmonella Cero werefound in stool samples from people reporting illness and entero-aggregative E.coli and Shigella were identified on molecular PCR testing of stool samples. It isnot possible to say conclusively whether or not illness in these cases was causedby contaminated food from the event.3 Elvis et al. Microbiological study of fresh herbs from retail premises uncovers an international outbreak ofSalmonella. International Journal of Food Microbiology 134 (2009) 83–8829

Understanding the risk from fresh leaves and safe food preparationAlthough well-documented in the scientific literature, it is unclear whether there iswidespread understanding among food handlers and the public regarding thepotential for contamination of herbs and spices with Salmonella and otherpathogenic organisms. Anecdotal information gathered by EHOs during theirinvestigation suggested that many of those who were unwell perceivedvegetarian food to be associated with a low risk of food borne illness and foodhandlers did not consider use of raw curry leaves to be associated with significantrisk.This outbreak highlighted areas of uncertainty around the use of uncooked freshcurry leaves.Are they a ready to eat product i.e. intended for direct consumption?Fresh herbs are commonly used as a food ingredient in both the commercial anddomestic setting. The majority of fresh herbs can be consumed raw or added tofood after cooking depending on local culinary practices. Used in this way, herbsare considered to be in a ready-to-eat state. Regulation (EC) No. 2073/2005 onmicrobiological criteria for foodstuffs defines ready-to-eat food as “food intendedby the producer or manufacturer for direct human consumption without the needfor cooking or other processing effective to eliminate or reduce to an acceptablelevel micro-organisms of concern” 4 .This may be open to interpretation. Staff at the restaurant involved in thisoutbreak usually add curry leaves to food that is further cooked, so that leavesare not ingested in their raw form. At this event, different types of food, fromanother region of India, were prepared and the leaves were used raw.During the investigation, the OCT members tried to establish whether this wasconsidered “normal practice” when preparing the coconut chutney. Severaldifferent recipes for coconut chutney were found and these included use of rawleaves and the use of “tempered” leaves (where leaves are heated, sometimes ina small amount of oil, in a frying pan for between few seconds to a minute), thusmaking it difficult to establish whether the practice of using raw leaves is“accepted practice” in this style of cooking.How to make the use of leaves safeThe fresh curry leaves implicated in this outbreak were sold in bunches that werepackaged in unlabelled plastic bags without batch details or instructions for use.Consequently, people purchasing these leaves may have been unsure whetherthey were safe to use uncooked and whether they needed to be washed beforeuse. At the time of the outbreak, there was no published guidance from the UKFood Standards Agency regarding the use of curry leaves and specificallywhether these should be regarded as a ready to eat product.4 European Commission (EC), 2005a. Regulation (EC) No. 2073/2005 of 15 November2005 on microbiological criteria for foodstuffs. Official Journal of the EuropeanUnion L338, 1–2630

Research has described how some faecal organisms, including Salmonella,entero-aggregative E. coli and Shigella, can become tightly adhered to leavesand can survive for long periods of time 5 ; this would support the findings from thisoutbreak of Salmonella Agona PT40 on the leaves, suggesting contaminationprior to the leaves being packaged and transported to the UK. This also raisesquestions about whether washing the leaves would effectively remove pathogensfrom the raw product.Several factors influence the risk of transmission of pathogens on leaves and, assuch, determine which control measures will be most effective.Leaves can be contaminated pre- or post-harvest, and the ability to adhere toleaves differs depending on the organism. As attachment or adherence are prerequisitesfor contamination and subsequent transmission of pathogens thesefactors will also be important in assessing the risk to human health.Experiments have demonstrated that although post-harvest decontamination(with chlorinated solutions) reduced bacterial contamination, it did not completelyeradicate either natural microbial population or human pathogens.Of note, Salmonella Agona is thought to be less adherent to leaves than otherserovars (Typhimurium, Enteritidis and Seftenberg).EHOs at Newcastle are working with the importer and with their Home Authorityon improving the advice given to their customers on the use of curry leaves. Theimporters are currently developing a label for the product which will include clearinstructions for use.EHOs in Newcastle have also established that normal practice in the restaurant isto cook curry leaves, and therefore there was not an ongoing public health risk inthis situation.Use of molecular techniques in outbreak investigationThe use of molecular (PCR) methods in this outbreak investigation added to ourunderstanding of the burden of illness. Further use of these tests in outbreaksituations will help develop our understanding of the significance of findings andhow the new technologies can be used to support and refine outbreakinvestigation and the clinical significance of a wider range of gastro-intestinalpathogens.11. RecommendationsThe key recommendations from this outbreak investigation focus on the use ofuncooked ingredients in foods.As the investigation has highlighted, despite there being a wealth of scientificliterature about the transmission of human pathogens on the leaves of herbs andother leaves and their being advice on the Food Standards Agency website aboutthe safe use of herbs and spices, the risks associated with using raw curry leavesdo not appear to be recognised by food handlers.5 Berger et al. Fresh fruit and vegetables as vehicles for the transmission of human pathogens. EnvironmentalMicrobiology (2010) 12(9), 2385–239731

Furthermore, the members of the public appeared to consider vegetarian food“low risk” in terms of being the cause of their food poisoning.Therefore, our recommendations are:- Better guidance on the use of curry leaves (and other leaf herbs) should bedeveloped to ensure that the food handlers and the public understand thepotential risks and how to minimise them- The Food Labelling regulations 1996 require pre-packed food to be appropriatelylabelled. Action should be taken to ensure that curry leaves (and other herbs) arelabelled and include instructions for use- There should be further research into how often curry leaves are contaminatedand if they are, advice developed on their use in cooking.If curry leaves are rarely contaminated, we would conclude that this outbreakoccurred due to an unusual combination of circumstances- Prevention at source – more research into how the organism gets into / onto theingredient and ways of preventing it – recognising that post-harvest washing maybe too early, too late or the cause of contamination in the first place.As stated in the paper by Berger 6 et al, „A better understanding of plant,microbiological, environmental, farm, processing and food handling factors thatinteract with one another to determine whether contamination occurs, andwhether pathogens survive or proliferate will support the development ofevidence-based policies, procedures, and technologies aimed at improving thesafety of fresh produce’- Risk reduction during food preparation – research into the effectiveness ofwashing leaves in removing organisms and any appropriate guidelines,particularly with regards to leaves intended to be used in foods without cooking(noting that the method and timing of contamination may impact on theeffectiveness of washing)Some more general issues regarding food preparation and serving at largecatered events also arose in this outbreak and we recommend:- Further research into whether routine refrigeration of uncooked products mayhave reduced bacterial load in the foods that were contaminated- Food handlers working at festivals or other large events should retain samples offoods for a period after an event to analyse if necessary; although we recognisethere may be practical challenges to undertaking this- Festival organisers should maintain an updated list of participating vendors andrequest menus and recipes. This would assist greatly in the early stages ofinvestigations and facilitate the early identification of any on-going risk factors.6 Berger et al. Fresh fruit and vegetables as vehicles for the transmission of human pathogens. EnvironmentalMicrobiology (2010) 12(9), 2385–239732

We consider this could be achieved in ways that do not pose a significantadministrative burden.- Research into the growth of pathogens in uncooked food dishes and ways toprevent itThis outbreak was the first time that molecular (PCR) assay had been used onsuch a large number of “outbreak” specimens. The findings were helpful insuggesting a possible cause for the burden of illness, but further research on theuse of PCR assay in outbreak situations needs to be undertaken. In particular,we recommend that:- Research is undertaken on general (asymptomatic) and GI-ill (people withdiarrhoeal and / or other GI symptoms) population to help interpret PCR results- There should be clear communication between the clinical and FW&E laboratoryto discuss the microbiological (including molecular) tests to ensure a co-ordinatedapproach to testing human and food / environmental specimens- A proposal for a survey of the microbiological quality of curry leaves (and otherleaf herbs) intended to be used in foods without cooking should be added to theconsultation for the UK Coordinated Study Liaison Group Programme 2014-15The outbreak also highlighted the issue of “mixed pathogen” contamination as thecause of gastro-intestinal illness. We recommend:- Awareness-raising amongst health protection and microbiologicalprofessionals of this issue, including approaches to investigation whichidentify all possible pathogens.12. Actions taken as a result of this investigationRecommendation Action taken By whomBetter guidance on use ofcurry leaves for foodhandlers and the public A copy of this report has beenforwarded to the FSA with arequest that they consider ourfindings and report back on howadvice might be developedPHE andNCC The issue of contaminated leaveswill be presented to the AdvisoryCommittee on MicrobiologicalSafety of FoodEnsure that pre-packedcurry leaves (and otherherbs) are labelled andinclude instructions for useDiscussion with Home Authoritywith responsibility for the importerof the curry leaves about improvingthe information on the label on thepackaging of the curry leavesNCC33

Research intocontamination of curryleavesDiscussion with the scientificbranch of the FSA (plus copy ofthe report) with a request thatfurther sampling of imported curryleaves be consideredProposal for survey of curry leavesto be considered by the UKCoordinated Study Liaison GroupPHE andNCCPrevention ofcontamination at source Issue raised with FSA NCC andPHEResearch into effect ofrefrigeration on bacterialload in contaminated foodRetention of food samplesfrom large catered eventsRetaining lists of caterersand menus at largecatered eventsResearch into growth ofcontaminants in uncookedfood dishesUse of moleculartechnologies in outbreakinvestigation / use ofmolecular testing inhuman and food samplesand interpretation ofresultsAwareness of “mixedpathogen” contaminationas a cause of outbreaksDisseminate the findingsof outbreak investigationto professional audiencesin UK and further afield Issue raised with FSA NCC andPHE To be considered by FSA / LA FSA / LA To be considered by LA / FSA LA / FSA To be considered by FSA / LA FSA / LAA paper reporting the lessonsidentified in this outbreakinvestigation is being presented tothe PHE GI Programme Board –for consideration of pilot project ofuse of PCR in all outbreaksPresentation of findings andinvestigation techniques throughPHE professional networksAs above re molecular techniquesin outbreak investigationPeer-reviewed publicationConference presentationsACMSF reportEPIS updateCIEH network and journalPHEPHEPHE andNCC34

Appendix 1 – Cohort Study (survey 1)AimTo investigate the association between exposure to foods served at the festival with illness.MethodsA cohort study was undertaken in order to investigate the association between exposure to foodsserved at the festival with illness. As the Street Spice Festival was a free to attend event with anestimate of approximately 12,000 attendees over the three days, no list of attendees wasavailable. Accordingly invitations to participate in the survey were posted as links on the StreetSpice twitter and Facebook accounts, re-tweeted by the Newcastle City Council, the HPA and alsoby a number of participants, and through hard copy press releases. The press releases werereproduced in local and regional newspapers and reported on regional television. Initial invitationswere posted and released on Friday 8 March and repeat messages were issued over the courseof the next week. In addition those who had completed the survey were asked to encourage otherattenders within their household to participate, and to forward the invitations to any others thatthey were aware had attended.The invitations requested that all attendees at the festival complete an online questionnaire.Those posted onto websites contained a clickable link to the survey. Hard copy releasescontained a short link to the survey created using Tinyurl! TM . The questionnaire requestedinformation on demographics, attendance, gastrointestinal illness, vendors visited and food itemsconsumed. Based on analysis of the initial information collated by Environmental Health it wasdecided to include questions on the consumption of any food from all vendors, and detailedinformation on food items eaten from three of the vendors, being the vendors which cases mostfrequently reported having consumed food from. These were Sachins, The Rib Man and MonsieurCrepe. Foods from Sachins were subdivided into „standard‟ menu items from the regular Sachinsmenu, and „South Indian‟ foods which were prepared by a chef who had been specially invited tothe event and served from a separate part of the stall.The questionnaire created using SelectSurvey, an application hosted and maintained by theHealth Protection Agency (HPA), and held on the secure SelectSurvey.NET network. The surveywas opened on Friday 8 March at 12 midday and closed on Monday 18 March at 10am. Figure 1shows a timeline for the study together with dates of twitter/FaceBook messages and pressreleases containing links.Data from the survey was downloaded and analysed using STATA 12 (StataCorp). Responseswere used only if complete; completeness was defined as containing answers to all demographic,attendance, illness and exposure questions. Responses were examined for duplicates; noduplicates of completed questionnaires were found. Analyses included descriptive epidemiology;univariate analysis of the association between exposure variables and illness by vendor, fooditem, day and time visited, using risk ratio (RR) as the effect measure; stratified analysis using themain risk factors to examine the effect of effect modification and confounding and a multivariableanalysis was completed using a logistic regression model. Statistical significance of relative riskswas inferred using 95% confidence intervals were calculated, along with p-values using Fisher‟sexact test.Interim results were presented to the OCT at meetings from the 11 March onwards.

AMPMAMPMAMPMAMPMAMPMAMPMAMPMAMPMAMPMAMPMAMPMAMPMAMPMAMPMAMPMAMPMAMPMAMPMAMPMNumber of responsesFigure 1: Timeline of events and number of responses500450400350300250200150100500Complete responses Press publishing link Twitter publishing linkEvent times HPU notified OCT28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18Thu Fri Sat Sun Mon Tue Wed Thu Fri Sat Sun Mon Tue Wed Thu Fri Sat Sun MonResultsIn total 1,309 responses to the survey were received, of which 827 were complete; 353 (42.7%)males and 474 (57.3%) females. This equates to approximately 7% of the estimated 12,000attenders; an estimate of the male:female ratio of attenders was not available. The number ofattendees who became aware of the survey cannot be estimated. The age-sex distribution isshown in table 1; the distribution of cases is similar to that found in cases reported toEnvironmental Health.Cases were defined as anyone attending the Street Spice Food Festival that experienceddiarrhoea with onset between 12 hours and 5 days after attending. Of the 827 responders 306(37%) met this definition; a further 41 reported other gastrointestinal symptoms. The medianincubation period was 1 day; the epidemic curve is shown in the main report as Figure 1.Symptomatology is discussed in further detail in Appendix 2 (case follow up survey).Cases occurred in people attending the festival on each of the days. The proportion of surveyresponders who were ill was 35% of those attending on any day, and by individual day (1 to 3)was 33%, 32% and 44% respectively. The proportion ill on day 3 was significantly higher than thaton the first two days (P

Table 1: Respondents by Age, Sex and Case StatusAgegroupNMale% byagegroup% bygenderGenderNFemale% byagegroup% bygenderNTotal% byagegroup% bygenderCases

When Sachins standard food items were stratified by exposure to South Indian foods associationswere reduced (univariate RR 1.69, adjusted RR 1.23) suggesting that confounding between thedifferent foods had raised the univariate risk ratios (Table 4).Table 5 shows the effect of stratifying exposure to Sachins food items by coconut chutney. Theassociations with illness were similarly reduced.InterpretationThe response rate achieved by this cohort study is estimated at about 7% of attendees, based onthe organiser estimate of 12,000 attenders in total. This is a small proportion, but not surprising inview of the difficulties in issuing invitations to a dispersed population attending an event of thistype. The attack rate among responders (35%) was likely to be much higher than in attenders ofthe festival as a whole, as people who were ill were more likely to be motivated to respond. Thecapture – recapture study (Appendix 3) provides a range of estimates of the overall attack rate ofbetween 5.2% and 10.2% with a best estimate of 7.7%, equating to 926 cases. Using thesefigures the response rate in cases would be estimated as 33%, and the response rate in noncasesas 5%. A low response rate in a cohort study may be associated with the introduction ofbias if the respondents are not typical of the cohort as a whole. In particular the methods used toinvite responses might lead to an age-specific differential in response rates. Table 1 shows thatresponses were received from a broad range of ages, but there is no estimate of the agedistributionof attendees at the festival available to compare it with.However there is no obvious mechanism for such potential biases affecting the association foundwith an individual vendor, or with differing associations between illness and specific food itemssold by an individual vendor. It is concluded that while the cohort study did not of itself ascertainmeaningful attack rates, the associations with illness (Relative risks) are robust. The capture -recapture provides for a somewhat more precise estimate of attack rate.The univariate associations with South Indian and standard food items from the Sachins stallstrongly suggested that South Indian foods were the main reason that the vendor was associatedwith illness. However the standard food items were also significantly associated. The possiblereasons for this are either that they were also genuinely associated with illness, albeit with a lowerlevel of risk, or that the association was caused by confounding, which could occur becausepeople who consumed South Indian foods from the vendor and became ill also consumedstandard food items.Stratified analysis was undertaken to investigate this possibility. Stratification separatelyexamined the association of standard foods with illness in people who did and did not also eatSouth Indian items. If confounding is the cause of the association it should remove the associationwith standard items. This analysis found that the association with standard food items wasreduced but remained significant. This shows that at least some of the apparent association wascaused by confounding. The possible explanations for the remaining association are either thatthere was a genuine associated risk with the standard food items, or that there wasmisclassification between the categories such that survey respondents inaccurately reportedwhich foods they ate from Sachins. Such misclassification would not be surprising as respondentsmay have had difficulty either remembering precisely what they had eaten, or recognising thedescription of the food item on the questionnaire. However it is not possible to rule out thepossibility of a risk associated with the standard food items.When looking at individual food items, the coconut chutney was the item most strongly associatedwith illness, but several other foods were also associated. Both confounding and misclassificationare is very likely amongst these foods. Coconut chutney was served as an accompaniment to themain dishes, predominantly Dosa, so that the univariate risks of these foods would be expected to38

e very similar through confounding. In addition several of the foods were similar in appearanceand hence likely to be misreported, and furthermore, it is common for people to remember andreport eating a main dish, but to forget or omit to report accompaniments served with it. There isevidence for this latter phenomenon in that fewer people reported eating the chutney than reportedthe dosa it was served along with. These factors are considered to be the likely reason that therelative risks and proportion of cases explained associated with coconut chutney are lower than forSouth Indian dishes as a group, and that for South Indian foods is slightly less than for Sachins asa whole.Stratification of individual food items by consumption of coconut chutney greatly reduced theassociations with these other foods, while leaving several significantly associated with illness. Asdescribed above, the possible reasons for this remaining association lie with misclassification – forexample if people ill after consuming coconut chutney did not report consumption on theirquestionnaire – or a genuine risk associated with these other food items, or a combination of both.A genuine risk could occur because of a separate association of that food item with illness, orbecause of cross-contamination.ConclusionThe cohort study demonstrated a risk of illness associated with consuming foods from Sachins onany day of the festival, and within the items sold with the South Indian foods and within theseitems the strongest association was with coconut chutney. The magnitude of the association andproportion of cases explained very strongly suggest that this association was causal.It is considered that there is likely to have been misclassification of exposures in survey responsesbecause of the nature of the food item and that this may explain why the association with this fooditem is less than the association for South Indian and all Sachins foods as a group, but crosscontamination between foods cannot be excluded on the basis of this analysis. The study couldnot distinguish between these possibilities, but nevertheless provides strong evidence that thecoconut chutney was the main vehicle of infection.39

Table 2: Risk of becoming ill associated with consumption of food from vendors at the Street Spice festival.VendorExposed Unexposed RiskTotal Cases AR% Total Cases AR% Ratio95% C.I.Pvalue% of casesexplainedSachins 414 273 65.9 404 31 7.7 8.59 [6.08-12.14] 0.000 89South Indian foods 281 244 86.8 537 60 11.2 7.77 [6.10-9.91] 0.000 80Standard foods 235 123 52.3 583 181 31.1 1.69 [1.42-2.00] 0.000 40The Rib Man 230 60 26.1 594 246 41.4 0.63 [0.50-0.80] 0.000 20Paleo 52 12 23.1 282 110 39.0 0.59 [0.35-0.99] 0.028 4El Kantina 47 13 27.7 285 113 39.7 0.70 [0.43-1.13] 0.117 4Las Paelleras 73 22 30.1 292 117 40.1 0.75 [0.52-1.10] 0.118 7Rasa Nusantara 77 36 46.8 260 96 36.9 1.27 [0.95-1.69] 0.121 12Love Food 45 12 26.7 287 110 38.3 0.70 [0.42-1.15] 0.131 4Pit Stop 59 27 45.8 288 108 37.5 1.22 [0.89-1.67] 0.236 9Tasty Thai Deli 104 36 34.6 272 111 40.8 0.85 [0.63-1.15] 0.271 12Manjit's Kitchen 79 34 43.0 270 100 37.0 1.16 [0.86-1.56] 0.335 11LuLu Chai 60 20 33.3 285 114 40.0 0.83 [0.57-1.22] 0.336 7Ramside Hall 77 31 40.3 278 104 37.4 1.08 [0.79-1.47] 0.649 10Papa Ganoush 11 5 45.5 318 123 38.7 1.18 [0.61-2.28] 0.650 2Bar Popolo 116 43 37.1 281 110 39.2 0.95 [0.72-1.25] 0.699 14Riley's Fish Shack 176 65 36.9 253 98 38.7 0.95 [0.74-1.22] 0.705 21David Kennedy 119 47 39.5 265 102 38.5 1.03 [0.78-1.34] 0.852 15Monsieur Crepe 200 75 37.5 624 230 36.9 1.02 [0.83-1.25] 0.870 25Heavenly Mana 76 29 38.2 266 99 37.2 1.03 [0.74-1.42] 0.881 9Wiga Wigaa Chilli's 50 19 38.0 303 118 38.9 0.98 [0.67-1.43] 0.899 6Electric East 159 60 37.7 253 97 38.3 0.98 [0.76-1.27] 0.902 2040

Table 3: Risk of becoming ill associated with consumption of individual foods served on the Sachins stall and grouped foodcategories.Section ofExposed Unexposed RiskP % of casesIndividual food items95% C.I.Sachins stallTotal Cases AR% Total Cases AR% Ratiovalue explainedSouth Indian Coconut chutney 188 168 89.4 619 126 20.4 4.39 [3.73-5.17] 0.000 55South Indian Dosa 213 182 85.5 602 120 19.9 4.29 [3.62-5.08] 0.000 59South Indian Uttaphum 33 31 93.9 781 269 34.4 2.73 [2.40-3.11] 0.000 10South Indian Vada 61 53 86.9 753 247 32.8 2.65 [2.30-3.05] 0.000 17Standard Tamarind sauce 17 15 88.2 775 264 34.1 2.59 [2.12-3.16] 0.000 5South Indian Samba sauce 56 47 83.9 748 244 32.6 2.57 [2.21-3.00] 0.000 15Standard Yoghurt 27 20 74.1 776 270 34.8 2.13 [1.67-2.71] 0.000 7Standard Daal 19 14 73.7 791 282 35.7 2.07 [1.55-2.75] 0.001 5Standard Chickpeas 32 20 62.5 777 278 35.8 1.75 [1.31-2.32] 0.002 7Standard Mint chutney 21 14 66.7 785 279 35.5 1.88 [1.37-2.57] 0.003 5Standard Potatoes 16 11 68.8 796 288 36.2 1.90 [1.35-2.68] 0.007 4Standard Keema pav 60 32 53.3 754 270 35.8 1.49 [1.15-1.92] 0.007 10Standard Other food 9 7 77.8 818 299 36.6 2.13 [1.48-3.05] 0.011 2Standard Vegetable pav 24 14 58.3 790 287 36.3 1.61 [1.13-2.28] 0.028 5Standard Chicken tikka wrap 89 39 43.8 727 263 36.2 1.21 [0.94-1.56] 0.159 13Standard Chaat 57 26 45.6 757 275 36.3 1.26 [0.93-1.69] 0.161 841

Section ofExposed Unexposed Risk% of casesFood group consumed95% C.I. PSachins stallTotal Cases AR% Total Cases AR% RatioexplainedBothMain and/or Sidedishes414 273 65.9 404 31 7.7 8.59 [6.08-12.14] 0.000 89South IndianMain and/or Sidedishes281 244 86.8 537 60 11.2 7.77 [6.10-9.91] 0.000 80South Indian Main dishes 275 238 86.6 543 66 12.2 7.12 [5.65-8.97] 0.000 78Both Main dishes 390 259 66.4 428 45 10.5 6.32 [4.75-8.40] 0.000 85Both Side dishes 250 203 81.2 568 101 17.8 4.57 [3.79-5.50] 0.000 66South Indian Side dishes 198 175 88.4 620 129 20.8 4.25 [3.61-4.99] 0.000 57Standard Side dishes 87 60 69.0 731 244 33.4 2.07 [1.74-2.46] 0.000 20StandardMain and/or Sidedishes235 123 52.3 583 181 31.1 1.69 [1.42-2.00] 0.000 40Standard Main dishes 188 86 45.7 630 218 34.6 1.32 [1.09-1.60] 0.006 2842

Stratified analysisTable 4: Risk of becoming ill associated with consumption of Sachin Standard food items stratified by exposure to any South IndianitemSection ofSachins stallCrudeExposedStratumUnexposedStratumM-H adjustedPercentagechange (%)Food groupRR 95% CI RR RR RR 95% CIStandard All 1.69 [1.42-2.00] 1.04 2.64 1.23 [1.10-1.38] -26.90Standard Main dishes 1.32 [1.09-1.60] 1.03 1.98 1.18 [1.04-1.33] -10.89Standard Side dishes 2.07 [1.74-2.46] 1.03 3.82 1.23 [1.10-1.38] -40.3743

Table 5: Risk of becoming ill associated with consumption individual food items stratified by exposure to coconut chutneySection ofSachins stallFoodgroupIndividual fooditemCrudeExposedStratumUnexposedStratumM-H adjustedPercentagechange (%)RR 95% CI RR RR RR 95% CISouth Indian Main dish Dosa 4.29 [3.62-5.08] 0.99 5.69 1.92 [1.73-2.13] -55.23South Indian Main dish Uttaphum 2.73 [2.40-3.11] 1.08 4.63 1.38 [1.26-1.52] -49.26South Indian Main dish Vada 2.65 [2.30-3.05] 0.95 4.71 1.28 [1.15-1.44] -51.49Standard Side dish Tamarind sauce 2.59 [2.12-3.16] 1.14 2.99 1.32 [1.17-1.47] -49.2South Indian Side dish Samba sauce 2.57 [2.21-3.00] 0.97 3.16 1.08 [0.95-1.22] -58.05Standard Side dish Yoghurt 2.13 [1.67-2.71] 1.13 2.91 1.64 [1.37-1.96] -22.96- -Other sachinsfood2.13 [1.48-3.05] 1.12 3.31 1.44 [1.20-1.74] -32.15Standard Side dish Daal 2.07 [1.55-2.75] 1 3.07 1.41 [1.13-1.77] -31.67Standard Side dish Potatoes 1.9 [1.35-2.68] 1.13 2.51 1.56 [1.21-2.01] -18.04Standard Side dish Mint chutney 1.88 [1.37-2.57] 0.87 2.97 1.36 [1.03-1.79] -27.76Standard Side dish Chickpeas 1.75 [1.31-2.32] 1.13 2.04 1.41 [1.14-1.75] -19.14Standard Main dish Vegetable pav 1.61 [1.13-2.28] 1.13 1.66 1.28 [1.01-1.61] -20.56Standard Main dish Keema pav 1.49 [1.15-1.92] 1.04 2.12 1.48 [1.20-1.82] -0.7Standard Main dish Chaat 1.26 [0.93-1.69] 1.04 1.54 1.25 [0.98-1.59] -0.6StandardMain dishChicken tikkawrap1.21 [0.94-1.56] 1.03 1.26 1.12 [0.92-1.36] -7.7544

Appendix 2 – Case follow-up study (survey 2)AimTo document the symptomatology and some aspects of the burden of illness associated with theoutbreakMethodsA second survey directed at known cases of illness in attenders to the Street Spice festival wasundertaken in order to obtain further details of the symptoms experienced and some measures ofthe burden of illness. This was administered using an online survey using the sameSelectSurvey.Net application described in survey 1.A list of people reporting illness was collated from three sources; the Newcastle City CouncilEnvironmental Health Department list of people who had reported illness after attendance tothemselves or other local authorities; people reporting illness in response to survey 1; and peoplewho had had relevant specimens submitted to laboratories for testing having attended the festival.Available contact details were obtained from the de-duplicated list and each case contacted.The survey was sent by personalised email where email addresses were available; the emailscontained a unique link to the survey leading to a personalised questionnaire which was pre-filledwith information that had been given in previous answers given by that respondent to thequestions e.g. name. Where no email address was supplied, a letter containing a nonpersonalisedlink to the survey was posted to the case. A total of 527 invitations were sent, 361 byemail and 165 by post. A reminder email/letter was sent two weeks after the first contact. For anycases reporting continuing illness, a further follow-up email was sent two weeks after the surveywas closed to ascertain the duration of illness.The questionnaire asked respondents for detailed information about their symptoms, time off workand use of healthcare.Data from the questionnaire were downloaded and analysed using STATA 12 (StataCorp). Thecase definition used in the analysis was the same as for the cohort study; cases were defined asanyone attending the Street Spice Food Festival that experienced diarrhoea between 12 hoursand 5 days after attending.The survey was opened on the 28 th March, the reminder was sent on the 15 th of April and thesurvey was closed on the 29 th of April.ResultsThere were 374 responses, a 71% response rate, of whom 351 met the study case definition andwere included in the analyses. This exceeded the number of cases in the first survey.Symptomatology is shown in table 6. Diarrhoea formed part of the case definition; in addition 91%reported abdominal pain, 58% nausea and 18% vomiting. Fever was reported by 44%. Diarrhoeawas the most prolonged symptom, with median duration of 11 days and range at the time of thesurvey of 1-49 days; at that time 14 of 351 (4.0%) of cases had on-going diarrhoea. Abdominalpain also had a long duration with a median of 7 days and 11 people reporting continuing illness.There were relatively low numbers of cases reporting vomiting, 18% of cases, of those thatreported vomiting it was short lived with a median of 1 day.Fifty-eight cases (16.6%) reported a relapse of symptoms. The second episode of diarrhoea wereon average shorter than the first; first episode median duration 9 days, second episode medianduration 4 days (Table 7)45

Almost two thirds of cases visited any healthcare setting for their illness (table 8) and the meannumber of visits to any setting was 2.3. General practitioners were the most frequently consultedwith 41% of cases reporting attending for a mean of 1.5 visits. Two cases (0.53%) reportedhospital admission and a further 6 visited hospitals without admission (Table.One third of cases said they had contacted the Environmental Health Department (Table 9);however from Environmental Health records we know that more than twice this number actuallydid so. One fifth reported contacting the Health Protection Agency.Workdays were reported as missed by 207 cases, 59% of all cases and 70% of those in work(Table 10). The average number of days missed by these cases was 4.9. The adjusted estimate ofthe total number of cases from capture re-capture was 814 (See Appendix 3), applying the samepercentage of people who had days off work and the mean number of days missed, produces anestimate that the total number of days of work lost was 2363 days.InterpretationSymptomatology was broadly consistent with Salmonella infection, but also with a range of otherorganisms causing gastro-intestinal disease. The duration of symptoms and relapse rate werehigher than expected (Tables 6 & 7). The proportion of cases admitted was low (Table 8)compared with many other outbreaks and sporadic cases in the community. This suggests thatonly a small proportion experienced very severe disease; this may be a characteristic of theorganism(s) causing disease, but in addition it may reflect that the affected population, peopleattending a food festival, were a relatively health population not at high risk for food borne illness.However the use of other healthcare facilities, the percentage of respondents who missed work,(70%) and the amount of working time lost by them (median 3.2 days; total of 995 days)demonstrates that the disease nevertheless caused very significant illness and disruption tonormal life.Extrapolating the working days lost to the population estimated by the capture re-capture study,produces an estimate that the total number of days off work was 2363 days. This figure should betreated with some caution as it may be that people who suffered more prolonged symptoms weremore likely to have provided responses; however a significant fraction of the estimated number ofaffected people responded to the survey.ConclusionThe case follow-up study provided in depth information about symptoms experienced by the casesand the burden of illness. The pattern of symptoms is similar to that previously reported inSalmonella outbreaks, although the duration of symptoms was longer than expected. It is alsocompatible with illness caused by other organisms, including the entero-aggregative E. coli foundby PCR testing. There were also reports of relapse of symptoms. There was a high degree ofcontact with healthcare for the cases but the hospitalisation rate was very low.46

Table 6: Symptoms and duration of illness from case follow-up studyMedian DurationSymptom Number Percentageduration rangeDiarrhoea 351 100 11 1-49*still ill 14 - 27 25-49*not still ill 337 - 11 1-43Abdominal pain 320 91 7 1-47*still ill 11 - 34 14-47*not still ill 308 - 7 1-34Nausea 203 58 3 1-28Fever 155 44 2 1-14Vomiting 64 18 1 1-6Table 7: Relapse of symptomsCategory Number PercentageMean duration(days)Medianduration(days)Range ofduration(days)First episode 350 100 10.9 9 1-49Second episode 58 16.6% 5.5 4 2-16Days to relapse 58 - 3.8 2 1-26Total days withdiarrhoea 351-11.6 10 1-49Table 8: Healthcare seeking behaviourHealthcare settingNumber of casesattended/ sought advicePercentage Mean times visited/contacted Range times visited/contactedAny of the settings 227 64.7 2.30 1-8GP 143 40.7 1.48 1-5NHS Direct 42 12.0 1.14 1-3Walk-in Centre 16 4.6 1.06 1-2Hospital -any 8 2.3 1.25 1-3Hospital -admission 2 0.53 - -The mean number of settings visited or contacted was 1.77, with a range of one to five settings.47

Table 9: Contacting Health Protection AgenciesPublic Health AgenciesNumber of casesMean times Range timesattended/ sought Percentagevisited visitedadviceEH department 123 35.0 1.31 1-5HPA 70 19.9 1.14 1-4Table 10: Days off workOff work Number PercentagePercentage ofthose workingYes 207 59 70No 89 25 30N/A not working 55 16 -Total 351 100 100Mean days off work: 4.92 days Median days off work: 3.5 days Range days off work: 1-35Total number of days off work: 995 (N=202, 5 cases who missed work did not give the number of days missed)48

Appendix 3 – Capture Re-capture StudyAimsTo identify the true size of the outbreak in order to more accurately estimate the attack rate andburden of associated illness and potential for bias within the cohort study.MethodsA three source capture re-capture analysis was undertaken. The three datasets used were; peopleproactively contacting the Environmental Health department; people reporting illness in the cohortstudy (survey 1); and people attending the festival for whom a sample was sent to a laboratoryafter a health services contact. Cohort study cases were not restricted to the cohort study casedefinition. After data cleaning and standardisation all sources were fuzzy matched usingalgorithms based on forename, surname and date of birth within FEBRL, an open source fuzzymatching application. Results were verified by a manual check.The resultant dataset contained a list of unique individuals and the source(s) in which they theywere found. Capture re-capture analysis was then undertaken on this dataset. Wittes method wasused to undertake 2 source estimates and to test for independence using Excel (Microsoft). Asaturated loglinear model using Poisson regression used as calculate the final model in STATA 1212 (StataCorp) to estimate the number of uncaptured cases and total number of cases.ResultsTable 11 shows the number of individuals in each of the three data sources and Figure 2 (left handdiagram) illustrates the distribution of individuals between them.Tests for independence were undertaken using Wittes method (Table 12). The odds ratios showthat the datasets were not independent and that there were significant positive associationsbetween two of the three pairs of datasets. The third pair (Environment Health/Survey within Lab)had OR of 1.4 with wide confidence intervals.The saturated loglinear model was therefore chosen for the final model. The central estimate ofthe numbers of people ill not captured by any source was 334, and the estimated total number ofcases was 926. Confidence intervals were broad: 95% CI were 628 – 1224.Applying the ratio of cases to people reporting illness implied by the cohort study case definitionwould reduce these estimates to 88% of the values reported above; central estimate to 814, withrange 552 to 1076.Interpretation and ConclusionsThree source capture –recapture enables estimation of the true size of the population from whichpeople reporting illness arose despite the data sources not being completely independent; i.e.where it is more likely that an individual is in a data source if they are in another.The main estimates in this study were undertaken using a broader case definition than in thecohort study (survey 1) which excluded non-diarrhoeal illness and specified an onset period of 12hours to 5 days after exposure. It would not have been possible to apply the case definition to theother data sources; however it was considered that all gastrointestinal illness was the bestdefinition to use to estimate the total burden of illness. The purpose of the restrictive casedefinition used the cohort study was to reduce the risk of including any unrelated illnesses withinthe case group. However this definition may also exclude related cases of illness, falsely reducingany estimate of the numbers of cases associated with an outbreak. Approximately 10% of peoplereporting gastro-intestinal illness to the survey did not meet the cohort study definition; this groupreported similar incubation periods to those within the case definition and it was considered49

probable that many were cases of illness genuinely associated with the festival. The estimatesshould therefore be interpreted as an estimate of the numbers of cases of illness occurring afterattendance at the festival, with the recognition that some of this estimate may reflect backgroundcases of illness which may have occurred irrespective of attendance. Applying the proportion ofpeople reporting illness in survey 1 who met the cohort study case definition to the final estimatesprovides an adjusted estimate of the numbers of cases diarrhoeal illness with the specifiedincubation period.Using the central estimate (926), the estimated sensitivity of the individual data sources in respectof people experiencing gastro intestinal illness after attendance was 44% for reports to theEnvironmental Health department, 38% for cohort survey responses, and 15% for laboratoryspecimens (Table 13) and 64% for the combined dataset.The 95% confidence intervals around the central estimate are wide however, ranging from 628 to1224. This compares with an estimated number of served portions for the suspect food of 900 –1000; if this equated to a number of people consuming the item it would suggest the attack rate forany gastro intestinal illness associated with the suspected food items must be above 62.5% andcould be 100%, and for illness meeting the cohort study case definition was 55% to 100%However it is possible that the numbers of people consuming the items is more than the numberserved, as some people may have shared items, and the possibility of cross contamination ofother foods could also increase the numbers exposed. These estimates must therefore be treatedwith caution. The corresponding estimates for the illness attack rate in all festival attenders arebetween 5.2% and 10.2% with a best estimate of 7.7%.50

Table 11: Number of cases by route reportedReported byCasesCohort study (survey 1) 348EH department 406Lab 136Combined Dataset 592Figure 2: Matched cases by source datasetEHO (406) Survey (348) Cases not captured (334)182 117 157334604714 .15Lab (136)Estimated number of cases missed = 334 Estimated total number of cases = 926 (95% CI: 628 – 1224)

Table 12 Tests for independenceAnalysisOddsRatiop value(Fisher’s exact)Survey/EHO inside 1.4 0.530LabSurvey/Lab inside 2.0 0.003EHOEHO/Lab insideSurvey5.8 0.000Table 13: Sensitivity of Data Sources for people reporting gastrointestinal illnessSensitivitiesSurvey EHO Lab CombinedEstimate 38% 44% 15% 64%95% C.I Lower 55% 65% 22% 94%95% C.I Upper 28% 33% 11% 48%52

Appendix 4: Street Spice outbreak 8168: Food sample resultsSample DescriptionDateSubmittedCoconut Milk Powder 08.03.13Asafoetida 08.03.13Desicated Coconut 07.03.13Coconut Milk Powder 06.03.13Whole Green Chilli 06.03.13Fresh Corriander 06.03.13Birdseye WholeGreen Chilli 06.03.13Fresh Ginger 06.03.13Dried Curry Leaves * 06.03.13Urad Dall 06.03.13Dried Basmati Rice 06.03.13L.monocytogenesEnterobacteriaceaeC.perfingens Bacillus spp Bacillus sppSalmonellaE. coliNotdetectedNotdetectedNotdetected < 20 < 20 < 5 < 10 < 20 < 20 < 20Notdetected < 20 < 3 (MPN) < 10 < 10 < 20 < 20Notdetected < 10 < 10 > 90000 < 10 < 20 < 20Notdetected < 10 < 10 > 150000 < 10 Presumptive PresumptiveNotdetected < 10 200 Presumptive < 10 < 20 < 20Notdetected < 10 < 20 95000 < 10 Presumptive PresumptiveDetectedO:4 H:g * < 10 > 1100 150000 Presumptive Presumptive PresumptiveNotdetected < 20 < 3 (MPN) < 10 < 10 < 20 < 20Notdetected < 20 < 3 (MPN) < 10 < 10 < 20 < 20Notdetected < 20 < 3 (MPN) < 10 < 10 Presumptive PresumptiveE. coliO157S. aureusNotdetected < 20Notdetected < 20Notdetected < 20Notdetected < 20Notdetected < 20Notdetected < 20Notdetected < 20Notdetected < 20NotdetectedDried Long Grain Rice 06.03.13Swab Uncooked RiceContainer 06.03.13 < 20 < 10 < 20Swab Uncooked RiceContainer 06.03.13NotdetectedNot tested53

Swab Uncooked RiceContainer 06.03.13NotdetectedSwab Prep Bench 06.03.13 < 20 < 10 < 20Swab Prep Bench 06.03.13NotdetectedSwab Prep Bench 06.03.13NotdetectedSwab Shelf AbovePrep Bench 06.03.13 < 20 < 10 < 20Swab Shelf AbovePrep Bench 06.03.13Swab Shelf AbovePrep Bench 06.03.13Toor Dall 06.03.13NotdetectedNotdetected < 20 < 3 (MPN) < 10 < 10 < 20 < 20NotdetectedNotdetected < 20* the curry leaves were originally recorded as “dried” but it was confirmed on later checking that fresh leaves had been sampled54

Alert sent to GPS in North East – 6 March 2013Appendix 5: Outbreak communications materialsNorth East06/03/2013Dear DoctorGastrointestinal illness associated with the Street Spice Festival, NewcastleThe Health Protection Unit is investigating reports of gastrointestinal illness associated with theStreet Spice food festival held at Times Square in Newcastle between 28/02/2013 and02/03/2013. Cases have been reported across the North East.In order to assist with this investigation we would be grateful if you would:Formally notify any cases of suspected food poisoning associated with this eventArrange for your patient to submit a faecal specimen.o Please clearly label the request form with “ILOG 8168 – for processing at HPA lab,Newcastle”o Submit specimens through your usual routeThank you for your help. Please do not hesitate to contact the HPU if you require any furtherinformation.Yours sincerelyDr Kirsty FosterConsultant in Health ProtectionNorth East Health Protection Unit

Letter sent to people with negative stool sample results – sent from 13 March 2013Our Ref: kf/td 200313March 2013Health Protection Agency North East2 nd FloorCitygateGallowgateNewcastle upon TyneNE1 4WHTel 0844 225 3550Fax (0191) 221 2584Dear Patientwww.hpa.org.ukStreet Spice Outbreak – Information for People with Negative Lab ResultsI am writing with the results of the faecal (stool) sample that you submitted as part of theinvestigation into illness associated with the Street Spice Festival in Newcastle. The samplethat you submitted was negative for Salmonella (and also E coli O157, campylobacter andshigella which were also tested).What this means:This means that Salmonella bacteria have not been grown from the sample that you submitted.Does this mean that I didn’t have Salmonella?Not necessarily – it only means that the laboratory did not identify Salmonella from your sample.This can be for a number of reasons:Sometimes it can be difficult to grow bacteria in the laboratoryThe amount of Salmonella can vary between different samples in the sameperson and there may not have been sufficient bacteria in your sample to identifySalmonellaYou can still have symptoms after initial infection has goneWhy have only a small number of people tested positive for Salmonella?Over 300 people have reported being ill. However not all of these people have submitted aspecimen. For the reasons given above, not all of the samples from those who have beenunwell will be positive. This is the case in most outbreak investigations.Does this mean that tests were not reliable?No – samples are processed using the standard accredited tests used by all microbiologylaboratories.What does a negative result mean for the investigation of this outbreak? The investigation of human specimens forms only one part of the investigation. Wealso look closely at the symptoms people have had and what they have reportedeating including the online survey which you may have completed. Samples of foodare also investigated.

As you are likely to be aware from the media, the investigation into this outbreak isstill ongoing.You will still be considered as a case because you became unwell with symptoms offood poisoning after visiting the Street Spice Festival.What should I do if I am still unwell? The symptoms of Salmonella and other types of food poisoning include abdominalpain and cramps, diarrhoea and vomiting. These are unpleasant but most peoplerecover within about a week. You should not return to work or school for 48 hoursafter your last symptoms of diarrhoea or vomiting. Contact your own GP if yoursymptoms are not improving or are getting worse.Yours sincerelyDr Kirsty FosterConsultant in Health ProtectionOn behalf of the Outbreak Control Team

Update on investigation sent to people reporting illness – sent 21 March 2013Information about on-going investigation into reports of illness following Street Spice festivalWe are aware that you reported illness that occurred after you attended the Street Spice Festival inNewcastle between 28 February and 2 March 2013 or completed the on-line survey.The investigation is on-going but we thought that it would be helpful to update you on the progress ofthe investigation and the infection identified.Update on findings to date:We have identified Salmonella from a number of people who have been ill and have found the samestrain of Salmonella in one of the food ingredients used at the festival.More detailed information about these findings, including the results of the food samples, will be madepublic once it is clear that this will not prejudice any formal actions that Newcastle City Council maydecide to take.As part of the investigation, we are looking at all ways in which the food could have becomecontaminated with Salmonella and whether there have been any breaches of food safety legislationwhere further action may be necessary.We do not believe there is an on-going risk to the public’s health following this outbreak, but areworking closely with organisations including the Food Standards Agency to ensure that any necessaryactions are taken and advice given.The information below describes the process of outbreak investigation and the next steps in ourinvestigation; we have also provided some information about Salmonella infection.The investigationFollowing reports of illness from people who attended the Street Spice Festival, a multi-agency outbreakcontrol team has been working to identify the cause of illness and the possible source of infections. Theoutbreak control team has representatives from different departments of the Health Protection Agencyand Newcastle City Council.Over 400 people have now contacted the Environmental Health (EH) department at Newcastle CityCouncil to report illness (mainly diarrhoea and abdominal pain but some also had vomiting and fever).

Information has been collected from everyone who contacted the EH department about the foods theyate at the festival and the day(s) they attended. A number of people have submitted faecal (stool)specimens which have undergone standard tests for common causes of these symptoms.The outbreak control team has been gathering information from a wide range of sources includingpeople who have been ill, the vendors who had stalls at the festival, the online survey and from foodsamples collected from vendors at the event.All this information is being brought together to try to establish the cause of the illness, inform thecontrol measures that are put in place to prevent any further cases of illness and to guide any furtheraction that may be needed.The illnessIt is not unusual in an outbreak investigation that some people who have been ill have a ‘negative’ resultfrom the samples given and there are several reasons for this. The amount of Salmonella can varybetween different samples in the same person, there may be insufficient bacteria in a sample to identifySalmonella and it can sometimes be difficult to grow the bacteria in the laboratory. Also, people cancontinue to have symptoms after the initial infection has resolved.However, in the investigation of an outbreak we classify people as ‘cases’ based on a number of factorsincluding laboratory results, the symptoms and timing of illness that they describe and the ‘exposures’they have had to a possible source of infection, in this case eating at the Street Spice event.We are aware that some people have had prolonged symptoms of diarrhoea and abdominal pain – thiscan happen with Salmonella infection. If you are concerned about on-going symptoms, please contactyour GP for clinical advice.We have shared information about the outbreak with GPs and hospitals across the region so they areaware of our findings to date.What happens next?Whilst we appreciate that people who have been unwell are keen to understand what has caused theoutbreak, the outbreak control team must be confident that all the relevant information has beenthoroughly reviewed before making findings public. As noted above, the formal legal investigation intothe outbreak is continuing and it is important that this is not prejudiced by the early release of detailedinformation on findings.When the outbreak investigation is finished, a report will be produced by the outbreak control team.Due to the size and complexity of the investigation, this report will take 6 - 8 weeks to compile.We have made every effort to send this update to everyone who reported illness following the event. Ifyou attended the event as part of a group / party, please share this information with anyone else whomay have been affected..Dr Kirsty FosterConsultant in Health Protection, North East Health Protection UnitChair of the Outbreak Control Team, 21 March 2013

Information to cases re follow-up study – sent 28 March 2013Street Spice Food Festival – further investigation into health effectsWe are contacting you because you reported illness after the Street Spice Festival tothe Environmental Health team in Newcastle.The type of Salmonella that has been identified from the outbreak investigation isuncommon and some people have reported that they have been unwell for morethan a week. This is unusual and we would like to ask some further questions sothat we can get a better understanding of the health effects of this particularinfection.The link below is for a survey to further investigate the symptoms and duration ofillness in people that attended the Street Spice Food Festival. Please be assuredthat all information will be treated with the strictest of confidence. The surveyshould take less than 10 minutes of your time.The link to the survey is:http://tinyurl.com/streetspice2The survey will be open until 9am on Monday 22 April.As outlined in the update that was sent out last week, the outbreak investigation isstill on-going. Newcastle City Council’s Environmental Health team may contact youagain as part of the on-going investigation into the source of the outbreak.Thank you, in advance, for responding to the surveyDr Kirsty FosterConsultant in Health Protection, North East Health Protection UnitOn behalf of the Street Spice Outbreak Control Team28 March 2013

Letters sent to cases with positive PCR resultsLetter for cases with pcr +ve result for EAECDearStreet Spice Festival investigation - Update on results and publication ofoutbreak reportI wrote to you in March about the result of the stool sample you submitted as part ofthe investigation of illness associated with the Street Spice Festival. I am writing toyou again to give you an update on the latest results and to inform you that theoutbreak investigation report is being published today.As you will know from the previous update we sent to people who had reportedillness, we detected an unusual strain of salmonella in samples from human casesand from a food ingredient used at the event.However, the number of confirmed salmonella cases we identified was relativelysmall considering the number of people reporting symptoms. In addition, manypeople suffered symptoms for longer than we typically see with salmonella infection.The laboratory tests normally undertaken had not detected organisms other thansalmonella, so we arranged for samples to be tested for other organisms using anew technique, called the polymerase chain reaction or PCR, which is still indevelopment. At present, this PCR is not part of the standard clinical tests used forthe diagnosis of gastro-intestinal infection so any results have to be interpreted withcaution.Many of the samples tested using the new technique were positive for EnteroaggregativeE Coli and Shigella, both these organisms are associated with travellers‟diarrhoea and causes symptoms such diarrhoea and abdominal cramp / pain whichwere similar to the symptoms many people reported in this outbreak. Affectedindividuals usually make a full recovery from such infections with no long termeffects.Your sample was one of these that tested positive which suggests you may havebeen infected with Entero-aggregative E Coli.We were not able to test food samples from the Festival using these techniques, sowe cannot demonstrate that the Entero-aggregative E.coli or Shigella organismswere in food at the festival.The outbreak report which we are publishing today includes a discussion of thesignificance of these findings. It concludes that this was a large outbreak of gastrointestinalillness, with Salmonella Agona PT 40 confirmed in 25 cases and alsoisolated from a food ingredient used at the event. It goes on to explain that findingsfrom further advanced laboratory analysis suggest that other organisms, includingEntero-aggregative E Coli and Shigella, may also have contributed to the burden ofillness experienced by people who attended the event.

Letters sent to cases with positive PCR resultsI have enclosed a copy of the Executive Summary of the report with this letter. If youwould like a copy of the full report, it is available on the Newcastle Council website.I‟d like to thank you for your co-operation with this complex investigation.Yours sincerelyDr Kirsty FosterConsultant in Health Protection / Chair of Outbreak Control Team

Letters sent to cases with positive PCR resultsLetter for cases with pcr +ve result for ShigellaDearStreet Spice Festival investigation - Update on results and publication ofoutbreak reportI wrote to you in March about the result of the stool sample you submitted as part ofthe investigation of illness associated with the Street Spice Festival. I am writing toyou again to give you an update on the latest results and to inform you that theoutbreak investigation report is being published today.As you will know from the previous update we sent to people who had reportedillness, we detected an unusual strain of salmonella in samples from human casesand from a food ingredient used at the event.However, the number of confirmed salmonella cases we identified was relativelysmall considering the number of people reporting symptoms. In addition, manypeople suffered symptoms for longer than we typically see with salmonella infection.The laboratory tests normally undertaken had not detected organisms other thansalmonella, so we arranged for samples to be tested for other organisms using anew technique, called the polymerase chain reaction or PCR, which is still indevelopment. At present, this PCR is not part of the standard clinical tests used forthe diagnosis of gastro-intestinal infection so any results have to be interpreted withcaution.Many of the samples tested using the new technique were positive for EnteroaggregativeE Coli and Shigella, both these organisms are associated with travellers‟diarrhoea and causes symptoms such diarrhoea and abdominal cramp / pain whichwere similar to the symptoms many people reported in this outbreak. Affectedindividuals usually make a full recovery from such infections with no long termeffects.Your sample was one of these that tested positive which suggests you may havebeen infected with Shigella.We were not able to test food samples from the Festival using these techniques, sowe cannot demonstrate that the Entero-aggregative E.coli or Shigella organismswere in food at the festival.The outbreak report which we are publishing today includes a discussion of thesignificance of these findings. It concludes that this was a large outbreak of gastrointestinalillness, with Salmonella Agona PT 40 confirmed in 25 cases and alsoisolated from a food ingredient used at the event. It goes on to explain that findingsfrom further advanced laboratory analysis suggest that other organisms, includingEntero-aggregative E Coli and Shigella, may also have contributed to the burden ofillness experienced by people who attended the event.

Letters sent to cases with positive PCR resultsI have enclosed a copy of the Executive Summary of the report with this letter. If youwould like a copy of the full report, it is available on the Newcastle Council website.I‟d like to thank you for your co-operation with this complex investigation.Yours sincerelyDr Kirsty FosterConsultant in Health Protection / Chair of Outbreak Control Team

Letters sent to cases with positive PCR resultsLetter for cases with pcr +ve result for EAEC and ShigellaDearStreet Spice Festival investigation - Update on results and publication ofoutbreak reportI wrote to you in March about the result of the stool sample you submitted as part ofthe investigation of illness associated with the Street Spice Festival. I am writing toyou again to give you an update on the latest results and to inform you that theoutbreak investigation report is being published today.As you will know from the previous update we sent to people who had reportedillness, we detected an unusual strain of salmonella in samples from human casesand from a food ingredient used at the event.However, the number of confirmed salmonella cases we identified was relativelysmall considering the number of people reporting symptoms. In addition, manypeople suffered symptoms for longer than we typically see with salmonella infection.The laboratory tests normally undertaken had not detected organisms other thansalmonella, so we arranged for samples to be tested for other organisms using anew technique, called the polymerase chain reaction or PCR, which is still indevelopment. At present, this PCR is not part of the standard clinical tests used forthe diagnosis of gastro-intestinal infection so any results have to be interpreted withcaution.Many of the samples tested using the new technique were positive for EnteroaggregativeE Coli and Shigella, which are both organisms usually associated withtravellers‟ diarrhoea and cause symptoms such diarrhoea and abdominal cramp /pain which were similar to the symptoms many people reported in this outbreak.Affected individuals usually make a full recovery from such infections with no longterm effects.Your sample was one of these that tested positive which suggests you may havebeen infected with Entero-aggregative E Coli and Shigella.We were not able to test food samples from the Festival using these techniques, sowe cannot demonstrate that the Entero-aggregative E.coli or Shigella organismswere in food at the festival.The outbreak report which we are publishing today includes a discussion of thesignificance of these findings. It concludes that this was a large outbreak of gastrointestinalillness, with Salmonella Agona PT 40 confirmed in 25 cases and alsoisolated from a food ingredient used at the event. It goes on to explain that findingsfrom further advanced laboratory analysis suggest that other organisms, includingEntero-aggregative E Coli and Shigella, may also have contributed to the burden ofillness experienced by people who attended the event.

Letters sent to cases with positive PCR resultsI have enclosed a copy of the Executive Summary of the report with this letter. If youwould like a copy of the full report, it is available on the Newcastle Council website.I‟d like to thank you for your co-operation with this complex investigation.Yours sincerelyDr Kirsty FosterConsultant in Health Protection / Chair of Outbreak Control Team

Letters sent to cases with positive PCR resultsLetter for cases with EAEC pcr and salmonella culture +ve resultsDearStreet Spice Festival investigation - Update on results and publication ofoutbreak reportI wrote to you in March because you reported illness after visiting the Street SpiceFestival in Newcastle. I am writing to you again to give you an update on the latestresults and to inform you that the outbreak investigation report is being publishedtoday.As you will be aware, Salmonella was identified by standard laboratory tests in thestool sample you submitted. However, further testing has identified that you may alsohave been infected with another bacteria called Entero-aggregative E Coli.As you will know from the previous update we sent to people who had reportedillness, we detected an unusual strain of salmonella in samples from human casesand from a food ingredient used at the event. However, the number of confirmedsalmonella cases we identified was relatively small considering the number of peoplereporting symptoms. In addition, many people suffered symptoms for longer than wetypically see with salmonella infection.The laboratory tests normally undertaken had not detected organisms other thansalmonella, so we arranged for samples to be tested for other organisms using anew technique, called the polymerase chain reaction or PCR, which is still indevelopment. At present, this PCR is not part of the standard clinical tests used forthe diagnosis of gastro-intestinal infection so any results have to be interpreted withcaution.Many of the samples tested using the new technique were positive for EnteroaggregativeE Coli and Shigella, which are both organisms usually associated withtravellers‟ diarrhoea and causes symptoms such as diarrhoea and abdominal cramp/ pain which were similar to the symptoms many people reported in this outbreak.Affected individuals usually make a full recovery from such infections with no longterm effects.Your sample was one of these that tested positive which suggests you may alsohave been infected with Entero-aggregative E Coli. This does not affect yourpositive Salmonella result, but suggests that you may have been infected with twodifferent organisms. It is possible for this to occur and more information is includedin the outbreak report.We were not able to test food samples from the Festival using these techniques, sowe cannot demonstrate that the Entero-aggregative E.coli or Shigella organismswere in food at the festival.The outbreak report which we are publishing today includes a discussion of thesignificance of these findings. It concludes that this was a large outbreak of gastro-

Letters sent to cases with positive PCR resultsintestinal illness, with Salmonella Agona PT 40 confirmed in 25 cases and alsoisolated from a food ingredient used at the event. It goes on to explain that findingsfrom further advanced laboratory analysis suggest that other organisms, includingEntero-aggregative E Coli and Shigella, may also have contributed to the burden ofillness experienced by people who attended the event.I have enclosed a copy of the Executive Summary of the report with this letter. If youwould like a copy of the full report, it is available on the Newcastle Council website.I‟d like to thank you for your co-operation with this complex investigation.Yours sincerelyDr Kirsty FosterConsultant in Health Protection / Chair of Outbreak Control Team

Letters sent to cases with positive PCR resultsLetter for cases with Shigella pcr and salmonella culture +ve resultsDearStreet Spice Festival investigation - Update on results and publication ofoutbreak reportI wrote to you in March because you reported illness after visiting the Street SpiceFestival in Newcastle. I am writing to you again to give you an update on the latestresults and to inform you that the outbreak investigation report is being publishedtoday.As you will be aware, Salmonella was identified by standard laboratory tests in thestool sample you submitted. However, further testing has identified that you may alsohave been infected with another bacteria called Shigella.As you will know from the previous update we sent to people who had reportedillness, we detected an unusual strain of salmonella in samples from human casesand from a food ingredient used at the event. However, the number of confirmedsalmonella cases we identified was relatively small considering the number of peoplereporting symptoms. In addition, many people suffered symptoms for longer than wetypically see with salmonella infection.The laboratory tests normally undertaken had not detected organisms other thansalmonella, so we arranged for samples to be tested for other organisms using anew technique, called the polymerase chain reaction or PCR, which is still indevelopment. At present, this PCR is not part of the standard clinical tests used forthe diagnosis of gastro-intestinal infection so any results have to be interpreted withcaution.Many of the samples tested using the new technique were positive for EnteroaggregativeE Coli and Shigella, which are both organisms usually associated withtravellers‟ diarrhoea and causes symptoms such as diarrhoea and abdominal cramp/ pain which were similar to the symptoms many people reported in this outbreak.Affected individuals usually make a full recovery from such infections with no longterm effects.Your sample was one of these that tested positive which suggests you may alsohave been infected with Shigella. This does not affect your positive Salmonellaresult, but suggests that you may have been infected with two different organisms. Itis possible for this to occur and more information is included in the outbreak report.We were not able to test food samples from the Festival using these techniques, sowe cannot demonstrate that the Entero-aggregative E.coli or Shigella organismswere in food at the festival.The outbreak report which we are publishing today includes a discussion of thesignificance of these findings. It concludes that this was a large outbreak of gastrointestinalillness, with Salmonella Agona PT 40 confirmed in 25 cases and also

Letters sent to cases with positive PCR resultsisolated from a food ingredient used at the event. It goes on to explain that findingsfrom further advanced laboratory analysis suggest that other organisms, includingEntero-aggregative E Coli and Shigella, may also have contributed to the burden ofillness experienced by people who attended the event.I have enclosed a copy of the Executive Summary of the report with this letter. If youwould like a copy of the full report, it is available on the Newcastle Council website.I‟d like to thank you for your co-operation with this complex investigation.Yours sincerelyDr Kirsty FosterConsultant in Health Protection / Chair of Outbreak Control Team

Letters sent to cases with positive PCR resultsLetter for cases with EAEC and Shigella pcr and salmonella culture +ve resultsDearStreet Spice Festival investigation - Update on results and publication ofoutbreak reportI wrote to you in March because you reported illness after visiting the Street SpiceFestival in Newcastle. I am writing to you again to give you an update on the latestresults and to inform you that the outbreak investigation report is being publishedtoday.As you will be aware, Salmonella was identified by standard laboratory tests in thestool sample you submitted. However, further testing has identified that you may alsohave been infected with two other bacteria - Entero-aggregative E Coli and Shigella.As you will know from the previous update we sent to people who had reportedillness, we detected an unusual strain of salmonella in samples from human casesand from a food ingredient used at the event. However, the number of confirmedsalmonella cases we identified was relatively small considering the number of peoplereporting symptoms. In addition, many people suffered symptoms for longer than wetypically see with salmonella infection.The laboratory tests normally undertaken had not detected organisms other thansalmonella, so we arranged for samples to be tested for other organisms using anew technique, called the polymerase chain reaction or PCR, which is still indevelopment. At present, this PCR is not part of the standard clinical tests used forthe diagnosis of gastro-intestinal infection so any results have to be interpreted withcaution.Many of the samples tested using the new technique were positive for EnteroaggregativeE Coli and Shigella, both are organisms which are usually associatedwith travellers‟ diarrhoea and cause symptoms such as diarrhoea and abdominalcramp / pain which were similar to the symptoms many people reported in thisoutbreak. Affected individuals usually make a full recovery from such infections withno long term effects.Your sample was one of these that tested positive which suggests you may alsohave been infected with Entero-aggregative E Coli and Shigella. This does notaffect your positive Salmonella result, but suggests that you may have been infectedwith three different organisms. It is possible for this to occur and more information isincluded in the outbreak report.We were not able to test food samples from the Festival using these techniques, sowe cannot demonstrate that the Entero-aggregative E.coli or Shigella organismswere in food at the festival.The outbreak report which we are publishing today includes a discussion of thesignificance of these findings. It concludes that this was a large outbreak of gastro-

Letters sent to cases with positive PCR resultsintestinal illness, with Salmonella Agona PT 40 confirmed in 25 cases and alsoisolated from a food ingredient used at the event. It goes on to explain that findingsfrom further advanced laboratory analysis suggest that other organisms, includingEntero-aggregative E Coli and Shigella, may also have contributed to the burden ofillness experienced by people who attended the event.I have enclosed a copy of the Executive Summary of the report with this letter. If youwould like a copy of the full report, it is available on the Newcastle Council website.I‟d like to thank you for your co-operation with this complex investigation.Yours sincerelyDr Kirsty FosterConsultant in Health Protection / Chair of Outbreak Control Team