Legionnaires' disease

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Legionnaires' disease

A type of pneumonia usually caused by infection with the bacterium Legionella pneumophila, but occasionally with a related species (such as L. micdadei or L. dumoffii). The disease was first observed in an epidemic among those attending an American Legion convention in Philadelphia, Pennsylvania, in 1976. The initial symptoms are headache, fever, muscle aches, and a generalized feeling of discomfort. The fever rises rapidly, reaching 102–105°F (32–41°C), and is usually accompanied by cough, shortness of breath, and chest pains. Abdominal pain and diarrhea are often present. The mortality rate can be as high as 15% in untreated or improperly diagnosed cases. Erythromycin, new-generation fluroquinolones, and rifampicin are considered highly effective medications, whereas the penicillins and cephalosporins are ineffective.

While epidemics of Legionnaires' disease (also referred to as legionellosis) can often be traced to a common source (cooling tower, potable water, or hot tub), most cases seem to occur sporadically. It is estimated that Legionella spp. account for approximately 4% of all community- and hospital-acquired pneumonia. Legionnaires' disease is most fequently associated with persons of impaired immune status. Legionella bacteria are commonly found in fresh water and moist soils worldwide and are often spread to humans through inhalation of aerosols containing the bacteria. Legionnaires' disease is not a communicable disease, indicating that human infection is not part of the survival strategy of these bacteria. Therefore, the legionellae are considered opportunistic pathogens of humans. It is technology (air conditioning) and the ability to extend life through medical advances (such as transplantation and treatments for terminal diseases) that have brought these bacteria into proximity with a susceptible population.

For most humans exposed to L. pneumophila, infection is asymptomatic or short-lived. This is attributed to a potent cellular immune response in healthy individuals. Recovery from Legionnaires' disease often affords immunity against future infection. However, no vaccine exists at the present time. See Medical bacteriology, Pneumonia

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.

Legionnaires’ disease

28 American Legion conventioneers die of flu-like disease in Philadelphia (1976). [Am. Hist.: Facts (1976), 573, 656]
See: Disease
Allusions—Cultural, Literary, Biblical, and Historical: A Thematic Dictionary. Copyright 2008 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
In August, investigators discovered that a cooling tower at the Opera House Hotel in New York City was the source of a nearly monthlong outbreak of Legionnaires' disease that caused 12 deaths and more than 120 cases of infection due to Legionellosis.
Pulsed-field gel electrophoresis (PFGE) patterns of samples from patients with legionellosis were identical to those observed in the water distribution system in five of the nine hospitals investigated from 1989 to 2006 (Garcia-Nunez et al., 2008).
Other sporadic case reports of neonatal legionellosis after water birth have been published worldwide during the last decade (9-11).
Because single reports of elevated Legionella serum antibody titers are not diagnostic for legionellosis, those reports are investigated on a case-by-case basis.
Seventy-six and 78 laboratory cases of legionellosis were diagnosed in 2008 and 2009, respectively (Table 3).
"Legionella and the Prevention of Legionellosis." World Health Organization.
Hospital-acquired legionellosis: solutions for a preventable infection.
Although confounding factors, such as the effect of concomitant immunosuppressive medications or disease, are possible contributors, TNF-[alpha] antagonists themselves are likely to contribute substantially to the high risk for legionellosis in these patients.
States also are encouraged to report cases to SLDSS to enhance detection of travel-related outbreaks and to provide information on additional legionellosis case variables not captured by NNDSS.
Systematic review and meta-analysis: urinary antigen tests for legionellosis. Chest.
Legionellosis (Legionnaires' disease and Pontiac fever) is an environment-related, acute respiratory infection caused by gram-negative, rod-shaped bacteria of the genus Legionella.