LEGIONELLA - World Health Organization

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The target levels defined in Box 6.1 are seen as the best way to minimize the risk. The alert level is designed to ensure that relevant people are informed, and that corrective actions (e.g. a review of the procedure for maintenance, or new controls) are instigated. When the maximum level is reached, disinfection of the water distribution system must be organized and the procedure for maintenance revised. Additionally, an independent body (e.g. local sanitary authorities) should carry out a new inspection before authorization for reuse is given. Operationally, control measures, such as temperature, disinfectant residual and pH should be monitored on line, as discussed in Chapters 4 and 5. Every case of nosocomial legionellosis constitutes an alert, meaning that other cases may have occurred or could occur in the future in the health-care facility (which would constitute an outbreak; see Box 6.2). Where there is a possibility of a nosocomial case, it should always be investigated. Box 6.2 Definition of a nosocomial outbreak A nosocomial outbreak is defined as two or more confirmed cases of legionellosis in the same hospital or residential institution within a six-month period. Location of the outbreak is defined in terms of geographical proximity of the cases and requires a certain level of judgement. The WSP and system assessment for control of Legionella in the hospital and the maintenance records must be reviewed by the following people, working together: • the incident and outbreak management control team • the person responsible for Legionella control • the appropriate hospital engineer • the infection control physician (hospital hygienist). The aim of the review is to ensure that the preventive procedures identified as necessary to prevent proliferation of and exposure to Legionella are followed. Any deficiency in the control procedures should be remedied as soon as possible. Sampling should be undertaken, followed by precautionary disinfection of parts of the water system, if this is considered to be justified. The incident and outbreak control management team should always include an expert in environmental monitoring of Legionella. Researchers should not be confined to the index case; it is important to also look for other previously undetected cases of legionellosis. The search should look for other confirmed or presumptive cases of Legionnaires’ disease associated with the hospital or community, unexplained cases of nosocomial pneumonia in patients (especially those with impaired immunity), and pneumonia in hospital staff. 00 <strong>LEGIONELLA</strong> AND THE PREVENTION OF LEGIONELLOSIS
Until the situation is under control, a critical review of every presumptive diagnosis of pneumonia in the hospital or residential institution must take place. It is the responsibility of the infection control doctor or hygienist to declare an outbreak and consider the measures outlined in Box 6.3. Box . Recommended correct ve act ons as part of an outbreak nvest gat on • Shut down any process capable of generating and disseminating airborne water droplets, and keep the system shut down until sampling procedures and any remedial disinfection, cleaning or other intervention have been completed. Final clearance to restart the system may be required. • Take appropriate samples from the system before any emergency disinfection is undertaken, for use in investigating the source of the outbreak. • Review and monitor staff health records to find out whether there are any further, undiagnosed cases of illness, and to help prepare case histories for affected people. • Review water systems records, and investigate any equipment or systems that could have been involved in the outbreak. For example, this may involve tracing all pipework runs, and taking statements from plant operative managers and from water treatment contractors or consultants. Any infringement of relevant legislation may be subject to formal investigation. • If a cooling water system has been identified as the source of an outbreak of Legionnaires’ disease, emergency cleaning of the system should be carried out as soon as possible (see Chapter 5). • If a water system other than a cooling system is involved in an outbreak of Legionnaires’ disease, an emergency treatment of that system should be carried out as soon as possible. 6.5.2 Establish documentation and communication procedures Table 6.4 gives an example of documentation for a routine monitoring and corrective action loop for a hot and cold-water system (see Chapter 5 for information on corrective action for cooling towers). <strong>LEGIONELLA</strong> AND THE PREVENTION OF LEGIONELLOSIS 0
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LEGIONELLA AND THE PREVENTION OF LE
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LEGIONELLA AND THE PREVENTION OF LE
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Foreword Legionellosis is a collect
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Contents Foreword . . . . . . . . .
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Chapter 5 Cooling towers and evapor
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Chapter 9 Disease surveillance and
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Tables Table 1.1 Main characteristi
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Figure 8.1 Visible biofilm on inter
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Acknowledgements The World Health O
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• John Newbold, Health and Safety
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Executive summary Legionellosis is
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• Health-care facilities — Chap
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Chapter 1 Legionellosis Britt Horne
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Legionnaires’ disease is often in
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1.1.2 Pontiac fever Symptoms Pontia
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Table . Extrapulmonary nfect ons ca
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Proteins produced by the body’s i
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Aspiration may occur in patients wi
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Table . R sk factors for Legionella
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In the outbreak of Legionnaires’
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Table . Potent al treatments for d
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1.4.2 Species and serogroups associ
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Other causes of infection In Europe
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The interaction of virulent legione
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1.5.2 Surface structures involved i
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1.5.4 Host defence The host defence
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Chapter 2 Ecology and environmental
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L. pneumophila is thermotolerant an
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2.2.3 Environmental factors and vir
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Figure 2.1 Biofilm formation Biofil
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2.4 Sources of Legionella infection
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Chapter 3 Approaches to risk manage
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Table . Cool ng tower outbreaks Fac
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Even when a source reaches a state
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The WSP should be prepared in conju
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Identify control measures Control m
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Page 75 and 76: Method Advantages D sadvantages Dos
Page 77 and 78: Validate effectiveness of water saf
Page 79 and 80: • clear statements of responsibil
Page 81 and 82: Chapter 4 Potable water and in-buil
Page 83 and 84: The remainder of this chapter provi
Page 85 and 86: 4.3.1 Document and describe the sys
Page 87 and 88: Construction materials — risk fac
Page 89 and 90: Where temperature controls (discuss
Page 91 and 92: 4.4.2 Monitor control measures This
Page 93 and 94: Chapter 5 Cooling towers and evapor
Page 95 and 96: 5.1.1 Cross-flow cooling towers As
Page 97 and 98: water treatments (including chemica
Page 99 and 100: 5.3 System assessment This section
Page 101 and 102: Spray drift — risk factors Even w
Page 103 and 104: The section on control measures for
Page 105 and 106: • periodic or continuous bleed-of
Page 107 and 108: Box . Po nts to be noted when clean
Page 109 and 110: In certain circumstances, samples m
Page 111 and 112: Table . Example documentat on for m
Page 113 and 114: Chapter 6 Health-care facilities Ma
Page 115 and 116: For 1999 and 2000, a total of 384 c
Page 117 and 118: 6.3 System assessment This section
Page 119 and 120: Table . Type of colon zat on of wat
Page 121 and 122: 6.4.1 Identify control measures Thi
Page 123: 6.5.1 Prepare management procedures
Page 127 and 128: Chapter 7 Hotels and ships Roisin R
Page 129 and 130: F gure . Detected and reported case
Page 131 and 132: Table . Rev ew of outbreaks (more t
Page 133 and 134: 7.2 Water safety plan overview WSPs
Page 135 and 136: The risk of legionellosis is increa
Page 137 and 138: Kingdom to 66% in Spain (Starlinger
Page 139 and 140: Agency, Legionella Section, United
Page 141 and 142: Given the complexity of distributio
Page 143 and 144: Chapter 8 Natural spas, hot tubs an
Page 145 and 146: Spas “Natural spa”, denotes fac
Page 147 and 148: Rare cases of Legionnaires’ disea
Page 149 and 150: Process step P pework Water n hot t
Page 151 and 152: Hosepipes may sometimes be used to
Page 153 and 154: Hot tubs that are not effectively d
Page 155 and 156: Nutrients — control measures Bath
Page 157 and 158: Various additives may also be used
Page 159 and 160: • descriptions of any significant
Page 161 and 162: Table . Examples of m crob olog cal
Page 163 and 164: Chapter 9 Disease surveillance and
Page 165 and 166: Exposure histories allow cases to b
Page 167 and 168: F gure . Invest gat ng a s ngle cas
Page 169 and 170: Box . (cont nued) Since the incepti
Page 171 and 172: Country United Kingdom All reported
Page 173 and 174: F gure . Annual reported cases, - 0
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Training opportunities Trainees in
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Box . Example of terms of reference
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ecause doing anything more could un
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9.4 Case studies This section descr
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9.4.4 Concrete batcher process on a
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Chapter 10 Regulatory aspects David
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• validation of the effectiveness
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• operating conditions, such as t
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10.4.6 Outbreak investigation and n
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hot water (e.g. health-care facilit
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General prevent on Country DW Wp SB
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Country General prevent on DW Wp SB
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Chapter 11 Laboratory aspects of Le
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• detection of the bacterium in t
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Method Sens t v ty (%) PCR • Rapi
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11.2.2 Detecting Legionella antigen
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DFA has been used successfully with
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• Serologic testing can be used f
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Although not all strains can be rel
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Generally, any water source that ma
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During outbreak investigations, swa
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• other Legionella species that d
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Appendix 1 Example of a water syste
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Weekly water system check list Week
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Appendix 2 Example of a 2-week foll
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Travel Work/travel in the UK: ❑ Y
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Checklist of local places Health/sp
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Appendix 3 Example of a national su
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Strictly Confidential 2 Hospital Ac
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Glossary aerobic bacteria Bacteria
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health-care acquired Legionellosis
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surveillance The process of systema
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References Abu KY, Eisenstein BI, E
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Barbaree JM et al. (1987). Protocol
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Blatt SP et al. (1994). Legionnaire
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Byrne B, Swanson MS (1998). Express
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Crespi S (1993). Legionella y legio
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Edelstein PH (1982b). Comparative s
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Falguera M et al. (2001). Nonsevere
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Gaia V et al. (2003). Sequence-base
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Hayden RT et al. (2001). Direct det
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Ingram JG, Plouffe JF (1994). Dange
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Ko KS et al. (2003). Molecular evol
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Loret JF et al. (2003). Comparison
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McEvoy M et al. (2000). A cluster o
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Olaechea PM et al. (1996). A predic
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Regan CM et al. (2003). Outbreak of
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Schulze-Robbecke R, Rodder M, Exner
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Surman SB, Morton LHG, Keevil CW (1
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Tully M, Williams A, Fitzgeorge RB
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Welti M et al. (2003). Development
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