title: Retrospective analysis of demographic and clinical factors associated with etiology of febrile respiratory illness among US military basic trainees.
abstract: BACKGROUND
  Basic trainees in the US military have historically been vulnerable to respiratory infections. Adenovirus and influenza are the most common etiological agents responsible for febrile respiratory illness (FRI) among trainees and present with similar clinical signs and symptoms. Identifying demographic and clinical factors associated with the primary viral pathogens causing FRI epidemics among trainees will help improve differential diagnosis and allow for appropriate distribution of antiviral medications. The objective of this study was to determine what demographic and clinical factors are associated with influenza and adenovirus among military trainees.
  
  
  METHODS
  Specimens were systematically collected from military trainees meeting FRI case definition (fever ≥38.0°C with either cough or sore throat; or provider-diagnosed pneumonia) at eight basic training centers in the USA. PCR and/or cell culture testing for respiratory pathogens were performed on specimens. Interviewer-administered questionnaires collected information on patient demographic and clinical factors. Polychotomous logistic regression was employed to assess the association between these factors and FRI outcome categories: laboratory-confirmed adenovirus, influenza, or other FRI. Sensitivity, specificity, positive and negative predictive value were calculated for individual predictors and clinical combinations of predictors.
  
  
  RESULTS
  Among 21,570 FRI cases sampled between 2004 and 2009, 63.6% were laboratory-confirmed adenovirus cases and 6.6% were laboratory-confirmed influenza cases. Subjects were predominantly young men (86.8% men; mean age 20.8 ± 3.8 years) from Fort Jackson (18.8%), Great Lakes (17.1%), Fort Leonard Wood (16.3%), Marine Corps Recruit Depot (MCRD) San Diego (19.0%), Fort Benning (13.3%), Lackland (7.5%), MCRD Parris Island (8.7%), and Cape May (3.2%). The best multivariate predictors of adenovirus were the combination of sore throat (odds ratio [OR], 2.94; 95% confidence interval [CI], 2.66-3.25), cough (OR, 2.33; 95% CI, 2.11-2.57), and fever (OR, 2.07; 95% CI, 1.90-2.26) with a PPV of 77% (p ≤ .05). A combination of cough, fever, training week 0-2 and acute onset were most predictive of influenza (PPV =38%; p ≤ .05).
  
  
  CONCLUSIONS
  Specific demographic and clinical factors were associated with laboratory-confirmed influenza and adenovirus among military trainees. Findings from this study can guide clinicians in the diagnosis and treatment of military trainees presenting with FRI.
authors.affiliation: Naval Health Research Center, 140 Sylvester Road, San Diego, CA, 92106, USA. dspadin@gmail.com.
authors.forename: Damaris S
authors.initials: DS
authors.lastname: Padin
authors.affiliation: Naval Health Research Center, 140 Sylvester Road, San Diego, CA, 92106, USA. dennis.faix@med.navy.mil.
authors.forename: Dennis
authors.initials: D
authors.lastname: Faix
authors.affiliation: Graduate School of Public Health, San Diego State University, 5500 Campanile Drive, San Diego, CA, 92182, USA. sbrodine@mail.sdsu.edu.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Brodine
authors.affiliation: Graduate School of Public Health, San Diego State University, 5500 Campanile Drive, San Diego, CA, 92182, USA. hlemus@mail.sdsu.edu.
authors.forename: Hector
authors.initials: H
authors.lastname: Lemus
authors.affiliation: Naval Health Research Center, 140 Sylvester Road, San Diego, CA, 92106, USA. anthony.hawksworth@med.navy.mil.
authors.forename: Anthony
authors.initials: A
authors.lastname: Hawksworth
authors.affiliation: Naval Health Research Center, 140 Sylvester Road, San Diego, CA, 92106, USA. shan.putnam@med.navy.mil.
authors.forename: Shannon
authors.initials: S
authors.lastname: Putnam
authors.affiliation: Naval Health Research Center, 140 Sylvester Road, San Diego, CA, 92106, USA. patrick.blair@med.navy.mil.
authors.forename: Patrick
authors.initials: P
authors.lastname: Blair
mesh_terms: D000257:Adenoviridae Infections / Q000150:complications / Q000453:epidemiology*; D003371:Cough / Q000209:etiology; D003710:Demography; D005260:Female; D005334:Fever / Q000209:etiology; D006801:Humans; D007251:Influenza, Human / Q000150:complications / Q000453:epidemiology*; D008297:Male; D008887:Military Medicine; D008889:Military Personnel; D012141:Respiratory Tract Infections / Q000150:complications / Q000453:epidemiology*; D012189:Retrospective Studies; D014481:United States / Q000453:epidemiology; D055815:Young Adult