Serosurvey of bacterial and viral respiratory pathogens among deployed U.S. service members

Background: Respiratory illnesses can cause substantial morbidity during military deployments. Bordetella pertussis, Chlamydia pneumoniae, Mycoplasma pneumoniae, adenovirus, parainfluenza, and respiratory syncytial virus (RSV) are hypothesized causes.

Purpose: To determine pathogen-specific seroprevalence prior to and after deployment in support of Operation Enduring Freedom (OEF).

Methods: A retrospective cohort study of 1000 service members deployed between June 30, 2004, and June 30, 2007, was conducted from 2008 through 2009. Pre- and post-deployment sera were tested for the presence of antibody to each pathogen.

Results: Pre-deployment IgG seropositivity was high for adenovirus, RSV, and parainfluenza (98.7%, 97.8%, and 81.6%, respectively), whereas seropositivity for B. pertussis, M. pneumoniae, and C. pneumoniae was 14.2%, 21.9%, and 65.1%, respectively. As defined by seroconversion in 1000 subjects, the following were identified: 43 new parainfluenza infections (24% of susceptibles); 37 new pertussis infections (4% of susceptibles); 33 new C. pneumoniae infections (10% of susceptibles); and 29 new M. pneumoniae infections (4% of susceptibles). B. pertussis seroconversion was two to four times higher than reports for the general U.S. population. Overall, 14.2% of the service members seroconverted to at least one of these six pathogens; this increased to 30.1% seroconversion when influenza was included. However, serologic testing was not clearly associated with clinical illness in this report.

Conclusions: Serologic evidence for respiratory infections was common among the 2004-2007 OEF-deployed military, sometimes at a higher rate than the general U.S. population. Awareness of this risk and implementation of preventive measures should be emphasized by leadership prior to and during deployment.