Legionnaires' disease: What you need to know

Legionnaires' disease has surfaced in Illinois, California and areas of New York and Pennsylvania. The disease is caused by bacteria, called legionella, which can be found in fresh water. Symptoms include severe pneumonia and in some cases the infection can be deadly. Should you worry about it? Mayo Clinic infectious diseases specialist Dr. Pritish Tosh says, while Legionnaires' disease can be a very serious infection, the general population should not panic about the recent outbreaks. "Legionnaires' disease is usually not a problem when concentrations are low. Unless you've been directly exposed to it, you're really not at risk." He says the infection is not spread from person to person. Instead, you get it by inhaling the bacteria that's been aerosolized.