LEGIONELLA - World Health Organization

F gure . Detected and reported cases of travel-assoc ated Leg onna res’ d sease n Europe
Number of cases
1500
1200
900
600
300
0
1994 1995 1996 1997 1998 1999 2000 2001 2002 2003
Source: Information obtained from the European Working Group for Legionella Infections (EWGLI) 6
7.1.2 Hotel-associated cases
Although the origin of most sporadic travel-associated cases is unknown, outbreaks have been
associated with hotels. Systematic investigation of sporadic travel-associated cases may shed
some light on their origin. A major challenge in determining the true source of cases is usually
the lack of clinical isolate from the patients. Since the method of diagnosis has moved towards
use of urinary antigen detection, it is now rare to have an isolate of Legionella from a patient
to compare by molecular typing methods with one from the environmental source.
Approximately 60% of hotel-associated cases of legionellosis are sporadic (EWGLI, 2003). The
epidemiological relationship between these sporadic cases and the hotel in question is considered
to be weak and is often not properly investigated, although it has occasionally been possible to
show a causal relationship (Muhlenberg, 1993). When there are several cases, constituting an
outbreak, there is an increased probability that the hotel will be the source of infection, and
such cases are usually investigated by the health authorities. The epidemiological relationship
between clusters and hotels has been corroborated microbially in several outbreaks, including
those affecting tourists of different nationalities (Joseph et al., 1996).
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Year
LEGIONELLA AND THE PREVENTION OF LEGIONELLOSIS 0