LEGIONELLA - World Health Organization

Figure 8.1 Visible biofilm on internal pipework of a hot tub, two weeks
after installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .128
Figure 9.1 Investigating a single case of legionellosis . . . . . . . . . . . . . . . . . . . . . . . . .143
Figure 9.2 Annual reported cases from six European countries, 1995–2004 . . . . . . . .148
Figure 9.3 Annual reported cases, 1994–2004, by category of exposure . . . . . . . . . . .149
Figure 10.1 Types of Legionella cases in Europe, by year of onset . . . . . . . . . . . . . . . . .168
Figure 11.1 Method of diagnosis of travel-associated Legionnaires’ disease
in Europe and year of onset of disease . . . . . . . . . . . . . . . . . . . . . . . . . . . .177
Boxes
Box 1.1 Classifications of nosocomial Legionnaires’ disease . . . . . . . . . . . . . . . . . . .10
Box 3.1 Hospital outbreak in which water sampling was ineffective . . . . . . . . . . . . .40
Box 3.2 Verification and validation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53
Box 4.1 Cold-water tap as a source of fatal nosocomial Legionella pneumonia
in a rehabilitation centre in the Netherlands . . . . . . . . . . . . . . . . . . . . . . . .58
Box 4.2 Components of potable water distribution system to be assessed . . . . . . . . .61
Box 4.3 Risk factors for growth of or exposure to Legionella in piped water systems . . . . .62
Box 5.1 An outbreak of legionellosis at the Melbourne Aquarium, April 2000 . . . . .72
Box 5.2 Components of cooling towers and evaporative condensers to be assessed . .75
Box 5.3 Example of corrective action procedure for emergency disinfection
and cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .82
Box 5.4 Points to be noted when cleaning and disinfecting . . . . . . . . . . . . . . . . . . .83
Box 6.1 Example of limit values for Legionella concentrations and
microbiological indicators in water used in health-care settings in France . . . . .99
Box 6.2 Definition of a nosocomial outbreak . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100
Box 6.3 Recommended corrective actions as part of an outbreak investigation . . . .101
Box 7.1 Potential sources of legionellae to be investigated in a system assessment . . . .110
Box 7.2 Factors exacerbating risks on board ships . . . . . . . . . . . . . . . . . . . . . . . . .111
Box 8.1 Types of pools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .120
Box 8.2 Examples of problems found with balance tanks in hot tubs in
commercial settings after a system assessment . . . . . . . . . . . . . . . . . . . . . .126
LEGIONELLA AND THE PREVENTION OF LEGIONELLOSIS xv