LEGIONELLA - World Health Organization

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considered as potential new species. A more detailed identification can be carried out in reference laboratories. Both environmental strains and clinical isolates can be successfully subtyped by molecular techniques, such as ribotyping, macrorestriction analysis by pulsed-field gel electrophoresis (PFGE), or PCR-based methods (Schoonmaker, Heimberger & Birkhead, 1992; Pruckler et al., 1995; Van Belkum et al., 1996; Ballard et al., 2000). The most accurate way to compare epidemiologically linked environmental and clinical isolates is to use two typing methods — genotyping (e.g. PFGE) and phenotyping (monoclonal subtyping) — in parallel (Drenning et al., 2001). An internationally recognized typing method using amplified fragment length polymorphism (AFLP) was tested on Legionella infections by 11 countries within the European working group (Fry et al., 2000; 2002). This method allows culture media to be compared without the need for transportation. In future, sequence-based typing methods, such as that described by Gaia et al. (2003), will be more commonly used. A consensus sequence-based scheme based on this previous work, using a standard protocol and dedicated web site 27 will greatly assist in timely epidemiological investigation, particularly of travel-associated cases of infection caused by L. pneumophila (Gaia et al., 2005). 11.4.3 Identifying appropriate sampling sites Selection of sampling sites depends on whether the sampling is for routine monitoring or to investigate an outbreak. The use of PCR for detecting nucleic acids of legionellae in the environment has been valuable in some investigations of legionellosis outbreaks, and is particularly useful for eliminating epidemiologically and geographically implicated sources. Quantitative methods are being developed for determining whether a potential environmental source is above guideline or mandatory levels contained in national legislation, where available (Ballard et al., 2000). The use of PCR to detect legionellae in the environment shows that up to 80% of fresh water is positive; this compares with only 20–40% when using culture to detect Legionella. The discrepancy could be due to the presence of non-viable or injured organisms, viable but non-culturable legionellae, a nonspecific reaction with unrelated organisms (although data suggest this is not the case), or the presence of new species of legionellae. The number and types of sites that should be tested to detect legionellae must be determined on an individual system basis. This is because of the diversity of plumbing, heating, ventilation and air-conditioning systems in the various institutions that may be sampled, which include industrial facilities, hotels, hospitals, retirement homes, public facilities and domestic environments. In 1987, an environmental sampling protocol was published, dealing with selection of appropriate sites to sample within a hospital (Barbaree et al., 1987) (see Table 11.2). This protocol can serve as a prototype for identifying sites that should be sampled in various institutions. 27 http://www.ewgli.org <strong>LEGIONELLA</strong> AND THE PREVENTION OF LEGIONELLOSIS
Generally, any water source that may produce aerosols should be considered a potential source for the transmission of legionellae (see Chapter 2). Legionellae require temperatures between 20 °C and 50 °C to multiply. Consequently, the bacteria are rarely found in municipal water supplies and tend to colonize warm water systems and point-of-use devices, particularly hot-water systems. Legionellae do not survive drying, and so condensation from air-conditioning equipment, which frequently evaporates to dryness, is not a likely source. High numbers of environmental legionellae, which grow only at 30 ºC or below and will not grow at 37 ºC, have been isolated from cold systems (Vladimir Drasar, OHS National Legionella Reference Laboratory, Czech Republic, personal communication, January 2005); however, these are unlikely to have any clinical significance. Table . Examples of env ronmental s tes for sampl ng for leg onellae Approx mate number of Volume S te samples of samples Potable water outs de or on boundary of health-care fac l ty property Treatment plant (raw and refined water) 2 10 litres Guardhouse or other facility if water is not fed from health-care facility 1 1 litre Fire hydrants General potable water system for health-care fac l ty 2 1 litre Incoming water pipe(s) 2 10 litres Water softener (pre and post) 2 1 litre Preheater (discharge side) 1 1 litre Primary heater (discharge side) 1 1 litre Circulating pumps 2 1 litre Holding tanks (cold water, discharge side) 2 1 litre Expansion tank for hot water 1 1 litre Back drain on sprinkler system(s) 2 1 litre Fireline where it branches off main system 1 1 litre Water used for respiratory therapy equipment 2 ≥ 1 Outlets in patients’ rooms A r compressor system 4 1 litre Vacuum water source Positive pressure equipment side 1 ≥ 100 ml Condensate from tank(s) 3 ≥ 100 ml Water separator(s) directly off compressors 4 ≥ 100 ml <strong>LEGIONELLA</strong> AND THE PREVENTION OF LEGIONELLOSIS
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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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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
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
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Page 171 and 172: Country United Kingdom All reported
Page 173 and 174: F gure . Annual reported cases, - 0
Page 175 and 176: Training opportunities Trainees in
Page 177 and 178: Box . Example of terms of reference
Page 179 and 180: ecause doing anything more could un
Page 181 and 182: 9.4 Case studies This section descr
Page 183 and 184: 9.4.4 Concrete batcher process on a
Page 185 and 186: Chapter 10 Regulatory aspects David
Page 187 and 188: • validation of the effectiveness
Page 189 and 190: • operating conditions, such as t
Page 191 and 192: 10.4.6 Outbreak investigation and n
Page 193 and 194: hot water (e.g. health-care facilit
Page 195 and 196: General prevent on Country DW Wp SB
Page 197 and 198: Country General prevent on DW Wp SB
Page 199 and 200: Chapter 11 Laboratory aspects of Le
Page 201 and 202: • detection of the bacterium in t
Page 203 and 204: Method Sens t v ty (%) PCR • Rapi
Page 205 and 206: 11.2.2 Detecting Legionella antigen
Page 207 and 208: DFA has been used successfully with
Page 209 and 210: • Serologic testing can be used f
Page 211: Although not all strains can be rel
Page 215 and 216: During outbreak investigations, swa
Page 217 and 218: • other Legionella species that d
Page 219 and 220: Appendix 1 Example of a water syste
Page 221 and 222: Weekly water system check list Week
Page 223 and 224: Appendix 2 Example of a 2-week foll
Page 225 and 226: Travel Work/travel in the UK: ❑ Y
Page 227 and 228: Checklist of local places Health/sp
Page 229 and 230: Appendix 3 Example of a national su
Page 231 and 232: Strictly Confidential 2 Hospital Ac
Page 233 and 234: Glossary aerobic bacteria Bacteria
Page 235 and 236: health-care acquired Legionellosis
Page 237 and 238: surveillance The process of systema
Page 239 and 240: References Abu KY, Eisenstein BI, E
Page 241 and 242: Barbaree JM et al. (1987). Protocol
Page 243 and 244: Blatt SP et al. (1994). Legionnaire
Page 245 and 246: Byrne B, Swanson MS (1998). Express
Page 247 and 248: Crespi S (1993). Legionella y legio
Page 249 and 250: Edelstein PH (1982b). Comparative s
Page 251 and 252: Falguera M et al. (2001). Nonsevere
Page 253 and 254: Gaia V et al. (2003). Sequence-base
Page 255 and 256: Hayden RT et al. (2001). Direct det
Page 257 and 258: Ingram JG, Plouffe JF (1994). Dange
Page 259 and 260: Ko KS et al. (2003). Molecular evol
Page 261 and 262: 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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