Outbreak of Group A Streptococcal Pneumonia among Marine Corps Recruits - California, November 1-December 20, 2002

Between Nov 1 and Dec 20, 2002, 163 Marines, including 160 recruits, were admitted to the Naval Medical Center San Diego for possible pneumonia; 128 cases were confirmed by chest radiograph. All pneumonia cases had the following investigations: sputum, blood, and throat cultures; Mycoplasma pneumoniae IgM and IgG; Chlamydia pneumoniae IgM and IgG; rhinoprobe DFA for respiratory syncytial virus, adenovirus, influenzae, and parainfluenzae; urine Legionella antigen test; urine Streptococcus pneumoniae antigen test; and an antistreptolysin O (ASO) titer. A definite case of Group A streptococcus (GAS) pneumonia was defined as a blood or pleural fluid culture positive for GAS. A probable case of GAS pneumonia was defined as a positive throat or sputum culture for GAS or an ASO titer of 250 Todd units or greater in the absence of another identified etiologic agent. A definite case of M. pneumoniae was defined as IgG seroconversion and a probable case as a positive IgM. A confirmed case of C. pneumoniae was defined as a 4-fold rise in IgG or an IgM titer of 16 or greater and a possible case as an IgG titer >=512. All cases were male with ages ranging from 18 to 33 years. One hundred thirty-two cases (81%) were white/non-Hispanic, 26 (16%) were white/Hispanic, three (2%) were Asian/Pacific Islander, and two (1%) were other. All cases were previously healthy and HIV-seronegative. Of the 128 cases of pneumonia, 66 (52%) had multilobar involvement, and 29 (23%) had a pleural effusion, including five (4%) with an empyema. Thirty-one (22%) of the pneumonia cases were caused by GASwith 6 cases of definite GAS and 25 cases of probable GAS. Forty-seven pneumonia cases were caused by other organisms, including 6 definite and 15 possible cases of C. pneumoniae, 3 definite and 16 probable cases of M. pneumoniae, 5 cases of adenovirus, and 2 cases of S. pneumoniae. Seventy-eight of 128 (61%) of pneumonia cases had a definite or probable diagnosis.