Legionellae is the cause of Pontiac fever,
a self-limited flu-like illness, and Legionnaires' disease (LD), a
severe multisystem disease involving pneumonia.
1
Legionnaires' disease can take the form of community-acquired
pneumonia, nosocomial pneumonia, and even traveler's pneumonia. An
estimated 8,000-18,000 cases of Legionnaires' disease occur in the
United States each year.
2 Approximately 90% of all
reported cases of Legionnaires' disease in the United States are
believed to be caused by
L. pneumophila;
L.
pneumophila serogroup 1 accounts for approximately 71% of all
culture-confirmed or urine antigen-confirmed cases.
3 The
CDC estimates that a mere 2-10% of cases are reported, partially
due to lack of testing. Populations at risk include persons over 60
years; smokers and those with chronic lung disease; and
immunocompromised individuals.
4
For more information about diseases caused by
Legionella,
please follow the links indicated below:
1 Fraser DW, Tsai TR, Orenstein W, Parkin WE, Beecham
HJ, Sharrar RG, Harris J, Mallison GF, Martin SM, McDade JE,
Shepard CC, Brachman PS. 1977.
Legionnaires' disease: description of an epidemic of pneumonia.
N. Engl. J. Med. 297:1189-1197.
2 Marston BJ, Plouffe JF, File TM, Hackman BA, Salstrom
SJ, Lipman HB, Kolczak MS, Breiman RF. 1997.
Incidence of community-acquired pneumonia requiring hopstalization
- results of a population-based active surveillance study in
Ohio. Arch. Intern. Med. 157:1709-1718.
3 Marston BJ, Plouffe JF, File TM, Hackman BA, Salstrom
SJ, Lipman HB, Kolczak MS, Breiman RF. 1994.
Surveillance for legionnaires' disease. Risk factors for morbidity
and mortality. Arch. Intern. Med. 164:2417-2422.
4 Bartlett J and C. J. Grace. 2003. Community-Acquired
Pneumonia and Bronchitis, p. 235,
in Medical Management of
Infectious Disease. CJ Grace (ed.), Marcel Dekker, Inc., New
York.