CHICAGO - Outbreaks of Legionnaires disease are often blamed on germs spewing from air-conditioning systems in big buildings, but new research shows home hot water pipes can be a source.
Legionnaires is a form of pneumonia caused by a bug that occurs naturally in water. The latest work suggests the bacteria often grow in the slimy gunk lining residential hot water pipes, and home water may be responsible for about 20 percent of cases.
Janet Stout, a microbiologist who heads the special pathogens lab at the Veterans Administration Medical Center in Pittsburgh, presented the findings Sunday to the American Society for Microbiology.
Stout estimates that between 2 and 5 percent of the 600,000 pneumonia cases requiring hospitalization in the United States each year are causes by Legionella pneumophilia bacteria.
The bacteria flourish at temperatures between 90 and 105 degrees. People catch the germs by inhaling drops of water.
Most people exposed to the bacteria never get sick. Those who are susceptible may include the elderly as well as people with diabetes or diseases that weaken the immune defenses.To kill off the Legionnaires bacteria in home systems, Stout recommends temporarily turning up the hot water tank temperature to above 140 degrees and running the hot water outlets for a half hour. This should be done every two or three months.
Another strategy is to let the shower run on hot for a few minutes before jumping in. This flushes out some of the bacteria that have built up in the pipes.