title: Epidemiology of pathogen-specific respiratory infections among three US populations.
abstract: BACKGROUND
  Diagnostic tests for respiratory infections can be costly and time-consuming. Improved characterization of specific respiratory pathogens by identifying frequent signs, symptoms and demographic characteristics, along with improving our understanding of coinfection rates and seasonality, may improve treatment and prevention measures.
  
  
  METHODS
  Febrile respiratory illness (FRI) and severe acute respiratory infection (SARI) surveillance was conducted from October 2011 through March 2013 among three US populations: civilians near the US-Mexico border, Department of Defense (DoD) beneficiaries, and military recruits. Clinical and demographic questionnaire data and respiratory swabs were collected from participants, tested by PCR for nine different respiratory pathogens and summarized. Age stratified characteristics of civilians positive for influenza and recruits positive for rhinovirus were compared to other and no/unknown pathogen. Seasonality and coinfection rates were also described.
  
  
  RESULTS
  A total of 1444 patients met the FRI or SARI case definition and were enrolled in this study. Influenza signs and symptoms varied across age groups of civilians. Recruits with rhinovirus had higher percentages of pneumonia, cough, shortness of breath, congestion, cough, less fever and longer time to seeking care and were more likely to be male compared to those in the no/unknown pathogen group. Coinfections were found in 6% of all FRI/SARI cases tested and were most frequently seen among children and with rhinovirus infections. Clear seasonal trends were identified for influenza, rhinovirus, and respiratory syncytial virus.
  
  
  CONCLUSIONS
  The age-stratified clinical characteristics associated with influenza suggest that age-specific case definitions may improve influenza surveillance and identification. Improving identification of rhinoviruses, the most frequent respiratory infection among recruits, may be useful for separating out contagious individuals, especially when larger outbreaks occur. Overall, describing the epidemiology of pathogen specific respiratory diseases can help improve clinical diagnoses, establish baselines of infection, identify outbreaks, and help prioritize the development of new vaccines and treatments.
authors.affiliation: Operational Infectious Diseases Department, Naval Health Research Center San Diego, San Diego, California, United States of America; Joint Doctoral Program in Public Health (Epidemiology), San Diego State University/University of California San Diego, San Diego, California, United States of America.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Radin
authors.affiliation: Operational Infectious Diseases Department, Naval Health Research Center San Diego, San Diego, California, United States of America.
authors.forename: Anthony W
authors.initials: AW
authors.lastname: Hawksworth
authors.affiliation: Operational Infectious Diseases Department, Naval Health Research Center San Diego, San Diego, California, United States of America.
authors.forename: Peter E
authors.initials: PE
authors.lastname: Kammerer
authors.affiliation: Operational Infectious Diseases Department, Naval Health Research Center San Diego, San Diego, California, United States of America.
authors.forename: Melinda
authors.initials: M
authors.lastname: Balansay
authors.affiliation: Department of Family and Preventive Medicine, University of California San Diego, La Jolla, California, United States of America.
authors.forename: Rema
authors.initials: R
authors.lastname: Raman
authors.affiliation: Graduate School of Public Health, San Diego State University, San Diego, California, United States of America.
authors.forename: Suzanne P
authors.initials: SP
authors.lastname: Lindsay
authors.affiliation: Operational Infectious Diseases Department, Naval Health Research Center San Diego, San Diego, California, United States of America.
authors.forename: Gary T
authors.initials: GT
authors.lastname: Brice
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D012141:Respiratory Tract Infections / Q000453:epidemiology* / Q000382:microbiology / Q000821:virology; D012621:Seasons; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology