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Legionnaires’ Disease in Portugal
In November, health authorities reported that seven people had died in Portugal following the country’s largest-ever outbreak of Legionnaires’ disease. The outbreak began in a suburb of Lisbon called Vila Franca de Xira and had infected more than 300 people by mid-December. The source of disease was suspected to be the cooling towers at a local fertilizer plant.
As precautionary measures, ornamental fountains in the outbreak area were closed and the chlorine concentration in tap water was increased. The Directorate-General for Health of Portugal also recommended that people avoid showers, Jacuzzis, and whirlpools; disinfect shower heads once a week by immersion in bleach solutions; and set the temperature on water heaters above 75°C (167°F). Information about Legionnaires’ disease appears below.
Legionnaires’ disease is a waterborne illness named after an outbreak at an American Legion convention in Philadelphia in 1976. The disease is caused by the bacterium L. pneumophila. The most common form of transmission is inhalation of contaminated aerosols produced in conjunction with water sprays, jets, or mists. Infection can also occur by aspiration of contaminated water. Outbreaks are typically associated with poorly maintained artificial water systems, hot and cold water systems in public and private buildings, and whirlpool spas.