The number of reported cases of Legionnaires' disease has significantly increased in the United States this year. Experts say outbreaks are expected, but the reports have been quickly coming in, from illnesses to deaths, that the anticipated numbers have even doubled in August alone.

Since the last reported case - the eighth death - in Illinois, health officials have been conducting investigations to find out what exactly is causing the outbreak. Experts still could not pinpoint the exact cause, but mentioned some factors affecting the increasing illness and death toll.

A combination of an aging population, better diagnostics, and increased awareness of Legionnaires' disease, possibly along with environmental factors, may put people at a higher risk of getting infected with the potentially deadly disease. An aging population would be more vulnerable to the disease, as in the reported cases at veterans' home in Quincy, Illinois.

According to the CDC, the first reported outbreak was in 1976, when people who attended the American Legion convention in Philadelphia suffered from severe lung infection or pneumonia, which was found to be Legionnaires' disease. The disease gets passed to a person by inhaling water droplets or mist infected with the Legionella bacteria, but cannot be passed from one person to another. Summertime to early fall is the best time to expect such outbreaks because the bacteria thrives in warm water. Legionella, however, may also persist even after the warm season. A person who catches the disease may experience a severe type of pneumonia, respiratory and kidney problems and septic shock. There is also a milder version of the disease, called Pontiac Fever.

In just four weeks that ended Aug. 29, reports of Legionellosis - Legionnaires' and Pontiac Fever - had risen to 404 cases. David Daige, spokesman for the CDC said this doubles outbreaks during the same time, same four weeks, in the last five years.

Dramatically contributing to the increasing reported cases of Legionnaires' disease are those in New York, Illinois and California. Along the Bronx in New York, 12 people have died due to the bacteria. In Illinois a veterans' home in Quincy has reported eight deaths. Meanwhile in California, inmates at the San Quentin State Prison have also been infected.

Investigations are still being conducted in these infected areas, but experts highlight the possible risk factors to getting the infection.

"As we complete those investigations, we'll have a better idea of why they happen and why so many people were affected," said CDC's medical epidemiologist Dr. Matthew Moore.

Photo: Yale Rosen | Flickr

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