Outbreaks of the disease usually receive major media attention, but most often this disease occurs as a single, isolated case. When outbreaks do occur they are usually in the summer or early fall, but cases occur year-round. Have chronic lung disease. Have diseases such as cancer, kidney failure that requires dialysis, diabetes, or AIDS, that suppress your immune system. Take drugs that suppress the immune system.
Pontiac fever occurs usually in individuals who are otherwise healthy.
Individuals may be exposed to these mists in homes, workplaces, hospitals, or other public places. Legionellosis is not passed from person to person, and there is no evidence that individuals can become infected from auto air conditioners or household window air conditioners. The Legionella organism can be found in many types of water systems. It has been found in certain plumbing systems, hot water tanks, cooling towers and evaporative condensers of large air-conditioning systems, and whirlpool spas. Legionellosis is believed to occur worldwide.