Prospective study of respiratory infections at the U.S. Naval Academy.

Midshipmen at the U.S. Naval Academy have recently suffered epidemics of upper respiratory tract infections. Seeking to determine cause, in June 1998 we enrolled 1,243 (99.5%) of 1,249 new midshipmen (plebes) and followed them during their first 11 months of training. Eighty-five plebes sought medical attention for acute respiratory disease. Using culture, serologic studies, and polymerase chain reaction, considerable evidence for respiratory pathogen infection was found among the ill subjects: Chlamydia pneumoniae in 41 (52.6%), Mycoplasma pneumoniae in 19 (25.3%), influenza in 11 (14.2%), Streptococcus pneumoniae in 6 (7.3%), and adenovirus in 1 (1.2%). Additionally, 873 (81%) the 1,077 plebes who completed an end-of-year questionnaire complained of having one or more respiratory symptoms (> 12 hours) during their first year of school. Of these, 132 (15%) reported that the symptoms significantly affected their performance. Study results suggest that respiratory infections were frequent, had a significant adverse impact on training, and were often attributable to bacterial pathogens.

Randomized, placebo-controlled clinical trial of oral azithromycin prophylaxis against respiratory infections in a high-risk, young adult population.

Military Special Forces trainees undergo intense psychological and physical stressors that often lead to respiratory infection. During 1998-2000, 477 Navy Special Forces trainees were enrolled in a double-blind trial of oral azithromycin (1 g given weekly) plus a placebo injection, compared with benzathine penicillin G (1.2 million U) plus azithromycin placebo tablets. Among the 464 subjects with complete data, 44 developed acute respiratory infection (20 with pneumonia) during the 2 weeks of most intense training; of these subjects, 12 (27.3%) had evidence of Chlamydia pneumoniae infection and 7 (15.9%) had evidence of Mycoplasma pneumoniae infection. Trainees who received azithromycin were less likely than were trainees who received benzathine penicillin G to develop acute respiratory infection (risk ratio, 0.50; 95% confidence interval [CI], 0.28-0.92) and less likely at the end of training to report episodes of breathing difficulty (odds ratio [OR], 0.59; 95% CI, 0.34-1.01) or sore throat (OR, 0.66; 95% CI, 0.41-1.05). Compared with benzathine penicillin G prophylaxis, weekly oral azithromycin was superior in preventing respiratory infection in this population at transient high risk.

Pneumococcal vaccine to counter emerging infectious disease threat in the military.

Streptococcus pneumoniae causes severe morbidity and mortality worldwide and poses a significant threat to the health and readiness of U.S. military personnel. Although a vaccine to prevent pneumococcal infections has been available for almost 25 years, its use has been limited. Recently, increasing antibiotic resistance among S. pneumoniae strains has emerged, prompting health care professionals to reevaluate the benefit of administering pneumococcal vaccine. The Naval Health Research Center, in collaboration with professionals from numerous civilian and military organizations, has initiated a rigorous double-blind, placebo-controlled trial investigating the operational value of vaccinating young adults as they enlist in the military.