The Centers for Disease Control and Prevention (CDC) is baffled by the rise in cases of Legionnaire's disease in the U. S. The number of cases of the disease, a form of pneumonia that can be fatal, has tripled in the last ten years.
Legionnaire's disease is transmitted by inhaling small water droplets that are contaminated with the Legionella bacteria. The disease is most likely to be caught in places with large, complex water supply systems, such as hospitals and hotels.
The number of cases of Legionnaire's disease was 1,110 in 2000 and rose to 3,522 in 2009. It's likely that even more people are infected, because the symptoms are often mild, consisting of flu-like symptoms of fever, chills, headaches, and cough. The disease can progress to more serious forms and is fatal in 5% to 30% of patients.
The disease itself is difficult to diagnose because it requires looking specifically for the Legionella bacteria, which won't be done unless the patient reports being in an area that places them at risk for the disease.
CDC officials suggested that the rise in the number of cases may be due to the increase in the number of seniors, who are particularly at risk for developing Legionnaire's disease. Infections among patients 80 years old or older quadrupled in the same time period. Nearly half the cases were in the 50 to 69 year-old age group.
The disease was named after an American Legion convention in 1976, where many attendees came down with an unknown disease, and 34 people died. The cause was eventually identified as a previously unknown type of bacteria and was named Legionella.
