LEGIONELLA - World Health Organization

For 1999 and 2000, a total of 384 cases of Legionnaires’ disease among residents of England
and Wales were reported to the Public Health Laboratory Service. Of these patients, 19 (5%)
acquired their infection in hospital. In 1999, there were seven single cases of Legionnaires’
disease among residents of England and Wales. Five of the seven people affected were
immunosuppressed, two were renal transplant patients and one was a cardiac transplant patient.
In 2000, 12 cases with five deaths were considered to be nosocomial. Half of these cases were
immunosuppressed, and three were associated with an outbreak in a hospital that had had a
previous outbreak (PHLS, 2002).
Table 1.7 in Chapter 1 shows the exposure setting for Legionnaires’ disease cases in France between
1999 and 2002. Due to an improvement in notification of legionellosis, the total annual
number of cases reported in France from 2000 to 2003 increased. However, the percentage of
nosocomial cases decreased annually and significantly, from 20% in 2000 to 9% in 2003. During
the same period, the percentage of cases reported in people staying in hotels and at camp sites
increased from 9% to 13% (Campese, 2004). This has been interpreted as a reflection of the
impact of measures taken by health institutions to control the risk of Legionnaires’ disease
following a ministerial circular in 1998.
6.2 Water safety plan overview
A WSP needs to be comprehensive; however, an overview of such a plan is shown in Table 6.1,
as an example of the type of information a plan might contain. As explained in Chapter 3, a
WSP is part of a framework for safe water quality that also includes health-based targets and
surveillance.
The remainder of this chapter provides information relevant to a WSP specific for potable
water and in-building distribution systems, for each of the three main areas of a WSP:
• system assessment (Section 6.3)
• monitoring (Section 6.4)
• communication and management (Section 6.5).
Sections 6.3–6.5 should be read in conjunction with Section 3.3 from Chapter 3.
Fundamentally, the responsibility for managing the risk of legionellosis belongs to the owner
or manager responsible for the potable water or in-building distribution system. To ensure
that the WSP is properly implemented, the owner or manager of the facility should assign
tasks, ensure that documentation is complete and current, and hold people accountable.
LEGIONELLA AND THE PREVENTION OF LEGIONELLOSIS