Outbreak of group A streptococcal pneumonia among Marine Corps recruits--California, November 1-December 20, 2002.

During November 1-December 20, 2002, a total of 163 Marine Corps personnel from the Marine Corps Recruit Depot (MCRD) in San Diego, California, including 160 new recruits, were admitted to the Naval Medical Center San Diego (NMCSD) for possible pneumonia. For 128 (79%) patients, pneumonia was confirmed by chest radiograph; of these 128 cases, 31 (24%) were definitely or probably caused by group A streptococci (GAS). This is the first outbreak of serious GAS-associated illness at a San Diego military training facility since the 1987 outbreak of rheumatic fever and the largest outbreak of GAS pneumonia in the United States since 1968. This report summarizes the results of the investigation of this outbreak, which indicate that GAS infection can occur among military recruit populations despite routine chemoprophylaxis administered to incoming recruits. Instituting routine surveillance for noninvasive GAS disease in military training facilities might prevent future invasive GAS outbreaks.