LEGIONELLA - World Health Organization

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Abbreviations and acronyms AFLP amplified fragment length polymorphism AIDS acquired immunodeficiency syndrome BAL bronchoalveolar lavage BCYE buffered charcoal yeast extract CAP community-acquired pneumonia CFU colony-forming unit DFA direct immunofluorescence assay DNA deoxyribonucleic acid EIA enzyme immunoassay EWGLI European Working Group for Legionella Infections GP general practitioner HEPA high efficiency particulate absorbing HPC heterotrophic plate count IFAT immunofluorescent antibody test ISO International Organization for Standardization LLAP Legionella-like amoebal pathogen MAb monoclonal antibody Mip macrophage infectivity potentiator MOMP major outer membrane protein PCR polymerase chain reaction PFGE pulsed-field gel electrophoresis PHLS Public Health Laboratory Service (UK) ppGpp guanosine 3’,5’-bispyrophosphate RNA ribonucleic acid UV ultraviolet WHO World Health Organization WSP water safety plan xx LEGIONELLA AND THE PREVENTION OF LEGIONELLOSIS
Executive summary Legionellosis is a collection of infections that emerged in the second half of the 20th century, and that are caused by Legionella pneumophila and related bacteria. The severity of legionellosis varies from mild febrile illness (Pontiac fever) to a potentially fatal form of pneumonia (Legionnaires’ disease) that can affect anyone, but principally affects those who are susceptible due to age, illness, immunosuppression and other risk factors, such as smoking. Legionella is an important pathogen in health-care acquired (nosocomial) pneumonia, particularly in immunocompromised patients. Legionella spp. can also cause community-acquired pneumonia, which has a high rate of hospital admission. Legionnaires’ disease is recognized as a major form of travel-associated pneumonia, and about 20% of the cases of legionellosis detected in Europe are considered to be related to travel; these cases present a particular set of problems because of difficulties in identifying the source of infection. Although Legionella is a wellrecognized problem in developed nations, data are scarce from developing countries. Since risk environments and susceptible populations are found worldwide, it is likely that the problem of Legionella is under-appreciated in developing countries. Chapter 1 describes the disease types caused by Legionella bacteria, including risk factors, prevalence and outcomes of Legionnaires’ disease. Although all Legionella species are considered potentially pathogenic for humans, Legionella pneumophila is the aetiological agent responsible for most reported cases of Legionnaires’ disease. Chapter 2 discusses the ecology and environmental sources of Legionella. Water is the major natural reservoir for legionellae, and the bacteria are found worldwide in many different natural and artificial aquatic environments and ranges of environmental conditions, such as cooling towers; water systems in hotels, homes, ships and factories; respiratory therapy equipment; fountains; misting devices; and spa pools. The fact that legionellae are found in hot-water tanks or thermally polluted rivers emphasizes that water temperature is a crucial factor in the colonization of water distribution systems. L. pneumophila has been shown to be able to withstand temperatures of 50 °C for several hours, but does not multiply below 20 °C (Fliermans, Soracco & Pope, 1981; Katz & Hammond, 1987; Colbourne et al., 1988; Bentham 1993). It is for this reason that the recommended temperature for storage and distribution of cold water is below 25 °C and ideally below 20 °C. Thus, the presence of Legionella in an aquatic environment and warm temperatures are two factors that can increase the risk of Legionnaires’ disease. The presence of biofilms is important for Legionella survival and growth in water systems. Legionellae are found in sources such as distributed drinking-water supplies, which then feed into water systems within buildings and cooling towers, accounting for the bacteria’s presence and subsequent growth in these artificial environments. LEGIONELLA AND THE PREVENTION OF LEGIONELLOSIS xx
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Page 5 and 6: Foreword Legionellosis is a collect
Page 7 and 8: Contents Foreword . . . . . . . . .
Page 9 and 10: Chapter 5 Cooling towers and evapor
Page 11 and 12: Chapter 9 Disease surveillance and
Page 13 and 14: Tables Table 1.1 Main characteristi
Page 15 and 16: Figure 8.1 Visible biofilm on inter
Page 17 and 18: Acknowledgements The World Health O
Page 19: • John Newbold, Health and Safety
Page 23 and 24: • Health-care facilities — Chap
Page 25 and 26: Chapter 1 Legionellosis Britt Horne
Page 27 and 28: Legionnaires’ disease is often in
Page 29 and 30: 1.1.2 Pontiac fever Symptoms Pontia
Page 31 and 32: Table . Extrapulmonary nfect ons ca
Page 33 and 34: Proteins produced by the body’s i
Page 35 and 36: Aspiration may occur in patients wi
Page 37 and 38: Table . R sk factors for Legionella
Page 39 and 40: In the outbreak of Legionnaires’
Page 41 and 42: Table . Potent al treatments for d
Page 43 and 44: 1.4.2 Species and serogroups associ
Page 45 and 46: Other causes of infection In Europe
Page 47 and 48: The interaction of virulent legione
Page 49 and 50: 1.5.2 Surface structures involved i
Page 51 and 52: 1.5.4 Host defence The host defence
Page 53 and 54: Chapter 2 Ecology and environmental
Page 55 and 56: L. pneumophila is thermotolerant an
Page 57 and 58: 2.2.3 Environmental factors and vir
Page 59 and 60: Figure 2.1 Biofilm formation Biofil
Page 61 and 62: 2.4 Sources of Legionella infection
Page 63 and 64: Chapter 3 Approaches to risk manage
Page 65 and 66: Table . Cool ng tower outbreaks Fac
Page 67 and 68: Even when a source reaches a state
Page 69 and 70: The WSP should be prepared in conju
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Identify control measures Control m
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F gure . Dec mal reduct on t mes fo
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Method Advantages D sadvantages Dos
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Validate effectiveness of water saf
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• clear statements of responsibil
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Chapter 4 Potable water and in-buil
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The remainder of this chapter provi
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4.3.1 Document and describe the sys
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Construction materials — risk fac
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Where temperature controls (discuss
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4.4.2 Monitor control measures This
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Chapter 5 Cooling towers and evapor
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5.1.1 Cross-flow cooling towers As
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water treatments (including chemica
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5.3 System assessment This section
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Spray drift — risk factors Even w
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The section on control measures for
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• periodic or continuous bleed-of
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Box . Po nts to be noted when clean
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In certain circumstances, samples m
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Table . Example documentat on for m
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Chapter 6 Health-care facilities Ma
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For 1999 and 2000, a total of 384 c
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6.3 System assessment This section
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Table . Type of colon zat on of wat
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6.4.1 Identify control measures Thi
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6.5.1 Prepare management procedures
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Until the situation is under contro
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Chapter 7 Hotels and ships Roisin R
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F gure . Detected and reported case
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Table . Rev ew of outbreaks (more t
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7.2 Water safety plan overview WSPs
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The risk of legionellosis is increa
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Kingdom to 66% in Spain (Starlinger
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Agency, Legionella Section, United
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Given the complexity of distributio
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Chapter 8 Natural spas, hot tubs an
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Spas “Natural spa”, denotes fac
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Rare cases of Legionnaires’ disea
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Process step P pework Water n hot t
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Hosepipes may sometimes be used to
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Hot tubs that are not effectively d
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Nutrients — control measures Bath
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Various additives may also be used
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• descriptions of any significant
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Table . Examples of m crob olog cal
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Chapter 9 Disease surveillance and
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Exposure histories allow cases to b
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F gure . Invest gat ng a s ngle cas
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Box . (cont nued) Since the incepti
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Country United Kingdom All reported
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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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LEGIONELLA - World Health Organization

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