Thirty years ago today, the U.S. Centers for Disease Control (CDC) announced that a team of researchers led by Joseph McDade had isolated the bacterium that causes Legionnaires' Disease. The CDC's discovery of Legionella in a hotel cooling tower ended months of speculation about a mysterious pneumonia-like illness which affected veterans at an American Legion convention in Philadelphia. Ultimately, over 250 men and women were stricken by the epidemic which became known as Legionnaires' Disease.
During the summer and fall of 1976, the CDC questioned over 4,400 conventioners and their families. Researchers took air, water, and soil samples from around the Bellevue-Stratford hotel, and autopsied 34 cadavers at the microscopic level. Although Joseph McDade was unable to grow the Legionella bacterium under laboratory conditions, he still obtained evidence of its existence and pathogenesis through experimentation.
Today, manufacturers and regulatory agencies mandate more stringent cleaning provisions for cooling towers and large-scale air conditioning systems. Still, between 8,000 and 18,000 people are hospitalized with Legionnaires' Disease each year. Initial symptoms include a high fever, chills, and cough. Some people also suffer from head and muscle aches. A milder infection caused by the same type of Legionella bacteria is called Pontiac Fever. Separately or together, Pontiac Fever and Legionnaires' disease comprise Legionellosis.
Resources:
http://www.cdc.gov/ncidod/dbmd/diseaseinfo/legionellosis_g.htm#1
http://justice.loyola.edu/~klc/BL472/Legionnaire/history.html
http://en.wikipedia.org/wiki/Legionella
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