"The bacteria responsible for Legionnaires' disease, legionellae, cause the disease when a susceptible person inhales aerosolized water contaminated with the bacteria. Sources of such water include showers, faucets, cooling towers and whirlpool spas. In buildings, legionellae grow in the biofilm or slime which develops within plumbing systems of buildings. Currently, there are no community interventions that have been shown to reduce the risk of Legionnaires' disease," says Barry Fields of the CDC, one of the researchers.
Fields and his colleagues looked at the effect of the decision of Pinellas County, Florida to change from chlorine to monochloramine to treat their municipal water supply. While treating the county water supply with chlorine, 20% of buildings tested for legionellae bacteria were positive. One month after the county converted its treatment to monochloramine the proportion of positive sites fell significantly to only 6% of buildings tested.
"These findings suggest that the use of monochloramine can drastically reduce legionellae in drinking water supplies and possibly prevent outbreaks of the disease," says Fields.
Previous studies conducted by the CDC have shown that municipalities that use monochloramine to treat their water supply were much less likely to have outbreaks of Legionnaires' disease than those using chlorine. Findings from the Pinellas County study provide additional evidence that monochloramine may be the first community-based intervention strategy for the control of Legionnaires' disease. Additional studies are needed to confirm these findings and to ensure that the use of monochloramine for water treatment does not cause other unanticipated problems, says Fields.
This release is a summary of a presentation from the 103rd General Meeting of the American Society for Microbiology, May 18-22, 2003, in Washington, DC. Additional information on these and other presentations at the 103rd ASM General Meeting can be found online at http://www.asm.org/Media/index.asp?bid=17053 or by contacting Jim Sliwa (jsliwa@asmusa.org) in the ASM Office of Communications. The phone number for the General Meeting Press Room is (202) 249-4064 and will be active from 12:00 noon EDT, May 18 until 12:00 noon EDT, May 22.