Food Act Report 2009/2010 - SA Health - SA.Gov.au

Food Borne Disease Investigations in South Australiain 2009–2010IntroductionThe Communicable Disease Control Branch (CDCB) of SA Health conducts epidemiological investigations into foodborne disease outbreaks in conjunction with Local Government Environmental Health Officers and the Food Policyand Programs Branch, which provide food technology and environmental investigation expertise and performenvironmental and food premises investigations. Primary Industry and Resources South Australia (PIRSA) staff alsoassist in trace back investigations. The Institute of Medical and Veterinary Science (IMVS) conducts microbiologicaltesting and molecular typing of food and environmental samples and isolates.Epidemiological information including food histories of cases, environmental reports of on-site visits to premisesand laboratory results of stool and food samples are collated to provide a descriptive analysis of clusters of cases.This information helps determine the appropriate analytical approach should further investigation be required.Epidemiological analysis may demonstrate a statistical association between illness and the consumption of aparticular food item or eating at particular premises. Microbiological and molecular evidence can support anassociation when a very similar or identical microorganism is found in both cases and a food vehicle suspectedon epidemiological grounds.The specific food vehicle or source of an outbreak is difficult to identify as often there is no remaining implicatedfood at the start of the investigation. Additionally, faecal samples from affected persons are not always providedfor testing.SA Health investigated nine outbreaks of gastrointestinal illness which were known or suspected to be food borneduring the period July 2009 to June 2010. Two outbreaks were associated with camps, two with private functions,one with a catered event, one with a restaurant, one with a bakery, one was a community outbreak and one wasassociated with a training facility.In addition, eight clusters of illnesses linked by a particular causative organism that are commonly, though notexclusively, food borne were investigated but the source was not identified. Where a cluster had cases associatedwith specific premises it may have been classified as an outbreak based on the strength of the association.A summary of outbreaks and clusters investigated during 2009–2010 and their settings is presented in Table 1.Outbreak No.1 Norovirus – Catered EventSA Health investigated an outbreak of 22 cases of gastroenteritis in people from two catered events in Adelaidein August 2009. Both events, a training course and a meeting, were served lunch that was prepared by the samecaterer. An inspection by an environmental health officer of the caterer implicated contaminated food from a sickfood handler. Advice was provided to the company regarding improvements in cleaning and sanitation. No furthercases of illness were reported.Outbreak No. 2 Suspected food borne gastroenteritis – CommunitySA Health in association with a local government council investigated a community outbreak of gastroenteritis inSeptember 2009. A total of eight cases of gastroenteritis in two groups of people from the same area were reported.Cases implicated two food premises in the same local government area; environmental inspection of premises did notreveal any issues of concern at either food premise.Outbreak No. 3 Shiga toxin producing E.coli (STEC) – CampIn November 2009 an outbreak of 31 cases of gastroenteritis in attendees at a four-day long camp was investigatedby SA Health. Of these, six were confirmed to be caused by STEC. Environmental investigation at the camp sitefound no environmental sources of STEC. No food from the camp was available for testing. A cohort study of 240camp attendees found that eating potato or pasta salad at the camp increased the risk of illness. The only commoningredient in the two salads was parsley; the source of the parsley is unknown. Advice was provided to the organisersregarding food safety and sanitation. No further reports of illness were received.page 23Food Act Report Year ending 30 June 2010