Epidemiology and control of acute respiratory diseases with emphasis on group A beta-hemolytic streptococcus: a decade of U.S. Army experience.

OBJECTIVE

To summarize the experiences of the U.S. Army regarding prevention and control, and frequencies, rates, trends, and determinants of febrile acute respiratory diseases (ARDs), particularly Group A beta-hemolytic streptococcus (GABHS).

METHODOLOGY

Since 1966, the U.S. Army has conducted routine surveillance of ARDs among basic trainees. Since 1985, all trainees with fever and respiratory tract symptoms have been cultured for GABHS: Field investigations were conducted when outbreaks of acute respiratory or GABHS-associated illnesses were detected. Mass plus tandem benzathine penicillin prophylaxis were used to interdict and control training center GABHS outbreaks.

RESULTS

During the period 1985 to 1994, there were 65,184 hospitalizations for acute febrile respiratory illnesses among Army trainees. The crude hospitalization rate was 0.45 per 100 trainees per week. The rate consistently declined over the period. Incremental declines were temporally associated with increased use of adenovirus immunizations and broader use of benzathine penicillin prophylaxis. During the period, 10,789 of 59,818 (18%) pharyngeal cultures were positive for GABHS: GABHS outbreaks were associated with diverse clinical manifestations including streptococcal toxic shock, acute rheumatic fever, and pneumonia. The emergence of mucoid colony morphology in clinical isolates was a consistent indicator of circulating virulent strains with epidemic potential. Outbreak-associated M types were M1, M3, M5, and M18. In response to six GABHS outbreaks, mass plus tandem benzathine penicillin chemoprophylaxis produced rapid and sustained GABHS control. ARD and GABHS recovery rates were lowest when benzathine penicillin prophylaxis was widely used.

CONCLUSIONS

ARD rates among Army trainees have consistently declined to unprecedented levels. GABHS has reemerged as an important threat to military trainees. Benzathine penicillin chemoprophylaxis is safe and effective for interdicting and preventing GABHS outbreaks in closed, healthy young adult populations.