Legionnaires’ Disease Update: Investigators Focus on Cooling Towers

For immediate release:
August 20, 2002

Contact: Linda Dorey
Vermont Department of Health

BURLINGTON—Health officials investigating an outbreak of 18 cases of Legionnaires’ disease in the Waterbury area have received test results on samples taken from area cooling towers.

As of 1 p.m. Tuesday, no additional cases of Legionnaires’ disease have been confirmed.

Test results on three Waterbury area cooling towers have shown the presence of Legionella pneumophila, the bacterium that causes Legionnaires’ disease. One additional cooling tower result is pending.

“Given the fact that 80 percent of cooling towers contain some level of Legionella bacteria, these results are not unexpected,” said Health Commissioner Dr. Jan K. Carney.

Because there are at least 15 different “serogroups” of Legionella pneumophila bacteria, other tests are being done to further identify the bacteria.

Health officials believe that one or more cooling tower is the likely source of this outbreak.

“These more specific tests can help us zero in on whether the outbreak is related to a single cooling tower,” Carney said.

Some early test results point to the cooling tower at the Dale building in the state office complex as a likely source, although health officials are not drawing any conclusions at this time.

A laboratory test was conducted to compare the bacteria in the cooling tower with bacteria on a clinical sample from the first person confirmed to have Legionnaires’ disease. The test showed that the bacteria share similar characteristics.

“This doesn’t yet mean that this cooling tower is the cause of the outbreak, but strengthens the possibility of a link between the two,” Carney said.

Further tests from the other cooling tower samples are pending. Results will not be available until sometime next week.

Nationally, bacteria growing in cooling towers has been associated with outbreaks of Legionnaires’ disease. According to the federal Centers for Disease Control and Prevention, the bacterium is a “ubiquitous aquatic organism that thrives in warm environments” and is found in an estimated eight out of 10 cooling towers.

Legionnaires’ disease is not passed from person to person. People get it by inhaling mists that contain Legionella pneumophila bacteria.

For more information on Legionnaires’ disease, visit the CDC website—www.cdc.gov/ncidod/dbmd/diseaseinfo/legionellosis_g.htm