University of Iowa Health Science Relations and
Daniel Diekema, MD, MS
Associate Professor of Internal Medicine/Pathology
First Published: 2000
Last Revised: November 2004
Peer Review Status: Internally Peer Reviewed

Legionnaires' disease, the potentially life-threatening pneumonia, no longer is headline news. But the bacteria that cause the disease still occur in the environment, says a University of Iowa internal medicine and pathology specialist.

Although these bacteria occur in the environment, healthy individuals usually need not worry about catching Legionnaires' disease, says Daniel Diekema, MD, MS, a clinical professor of internal medicine in the UI Carver College of Medicine. "For that reason, Legionnaires' disease only occasionally is a significant threat to public health," Diekema adds. He also is on the staff of UI Hospitals and Clinics.

People with weakened immunity--being treated for cancer or kidney failure--are among those more susceptible to the disease, he says.

Legionnaires' disease is usually characterized by pneumonia and can cause symptoms and signs including cough, shortness of breath, high fever, recurrent chills, diarrhea, liver and kidney function abnormalities, and, in some patients, confusion. If diagnosed early, Legionnaires' disease can be cured with antibiotics, he says.

The disease is named for its most severe epidemic, which occurred in 1976. The unknown disease attacked over 200 people gathered for an American Legion convention in Philadelphia.

Legionella, the bacteria that cause Legionnaires' disease, live in fresh water, including, occasionally, the water we drink and in which we bathe, Diekema says. The bacteria may be dispersed throughout our water systems, especially hot water systems, and can be removed by high-level chlorination or by heating the water higher than the normal hot water temperature, or by using commercial systems that use copper-silver ions or cholorine dioxide to kill Legionella.

"Our water purification processes have been effective in removing most types of harmful bacteria, but other organisms, like Legionella, can survive most standard treatments," Diekema says.

Legionnaries' disease is geographical in the way it occurs, and some areas such as Iowa see more of the disease than others. Scientists have not yet determined why there is a geographic variation for Legionnaires' disease, although it may be related to the difference in water supplies and water treatment methods across the country, Diekema says.

"It's important to understand that our environment has never been sterile and that we're constantly exposed to germs. As we learn more about the bacteria that cause Legionnaries' disease, new prevention standards are developed to reduce the likelihood of getting the disease," Diekema says.