LEGIONELLA - World Health Organization

Surve llance dataset Comment
Exposure h story
Hosp tal acqu red (nosocom al) Necessary to establish nosocomial association
Date(s) of admission to hospital(s)
before onset of symptoms
Commun ty acqu red
Necessary to begin environmental investigations
Known exposure to cooling towers,
whirlpool spas, showers, etc.
Travel assoc ated
Necessary to begin environmental investigations
Country visited, dates of stay, name
and address of accommodation used,
room number, name of tour operator,
use of showers, spa pools, etc.
Domest cally acqu red
If no other source of infection identified, this should
Use of domestic water system during be considered
incubation period, in absence of
other risk exposures
Single cases
Single cases reported to a surveillance scheme are normally entered into a database that is
then searched for links in time or place to previously reported cases. If no links are found, the
environmental actions in response to a single case will be determined locally or nationally.
However, whenever possible, these actions should include:
• a review of the possible sources of infection
• a risk assessment of potential or suspected sources (see Chapter 3).
A memorandum of understanding or a local or national protocol agreed in advance between
all the relevant agencies helps to facilitate this process and to ensure that all the appropriate
measures have been taken. Local documentation or registration of cooling towers is also
extremely helpful when searching for potential community sources of infection. A flowchart
for investigating single cases of legionellosis is given in Figure 9.1.
LEGIONELLA AND THE PREVENTION OF LEGIONELLOSIS