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Legionnaires’ disease bacteria lurk in tap water

Found in nearly half of faucets, contamination could explain sporadic cases of disease

11:16am, February 21, 2014

CONTAMINATED  In a small U.S. study, researchers found that nearly half of the 68 water facuets sampled had traces of Legionella pneumophila, which causes Legionnaires’ disease.

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Of 68 water taps that scientists sampled across the United States, 47 percent harbored traces of Legionella pneumophila. The bacterium causes Legionnaires’ disease, a severe form of pneumonia and flulike Pontiac fever — collectively referred to as legionellosis.

Though legionellosis is relatively rare with an estimated 8,000 to 18,000 infections annually nationwide, the vast majority of cases are not linked to an outbreak and monitoring for L. pneumophila can be difficult.

Chemist Maura Donohue of the Environmental Protection Agency in Cincinnati and colleagues collected 272 samples over two years from 68 water sources, including kitchen sinks, bathroom sinks, drinking fountains and a refrigerator water dispenser.

By probing for the bacterium’s genetic material, the researchers found that 32 taps contained L. pneumophila traces in at least one sample. Of those 32 taps, 11 contained the bacterium in multiple samples.

 The small study, which appears February 18 in Environmental Science & Technology, is one of the first to chart the national prevalence of L. pneumophila in water taps. The authors suggest that further research should investigate how the bacteria arrive in people’s sinks.


M.J. Donohue et al. Widespread molecular detection of Legionella pneumophila serogroup 1 in cold water taps across the United States. Environmental Science & Technology. Published online February 18, 2014. doi:  10.1021/es4055115.

Further Reading

J. Raloff. Amoebas in drinking water: a double threat. Science News. Vol. 179, February 26, 2011, p. 9.

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