title: Underrecognized mildly symptomatic viremic dengue virus infections in rural Thai schools and villages.
abstract: BACKGROUND
  The understanding of dengue virus (DENV) transmission dynamics and the clinical spectrum of infection are critical to informing surveillance and control measures. Geographic cluster studies can elucidate these features in greater detail than cohort studies alone.
  
  
  METHODS
  A 4-year longitudinal cohort and geographic cluster study was undertaken in rural Thailand. Cohort children underwent pre-/postseason serology and active school absence-based surveillance to detect inapparent and symptomatic dengue. Cluster investigations were triggered by cohort dengue and non-dengue febrile illnesses (positive and negative clusters, respectively).
  
  
  RESULTS
  The annual cohort incidence of symptomatic dengue ranged from 1.3% to 4.4%. DENV-4 predominated in the first 2 years, DENV-1 in the second 2 years. The inapparent-to-symptomatic infection ratio ranged from 1.1:1 to 2.9:1. Positive clusters had a 16.0% infection rate, negative clusters 1.1%. Of 119 infections in positive clusters, 59.7% were febrile, 20.2% were afebrile with other symptoms, and 20.2% were asymptomatic. Of 16 febrile children detected during cluster investigations who continued to attend school, 9 had detectable viremia.
  
  
  CONCLUSIONS
  Dengue transmission risk was high near viremic children in both high- and low-incidence years. Inapparent infections in the cohort overestimated the rate of asymptomatic infections. Ambulatory children with mild febrile viremic infections could represent an important component of dengue transmission.
authors.affiliation: Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand. yooni@afrims.org
authors.forename: In-Kyu
authors.initials: IK
authors.lastname: Yoon
authors.forename: Alan L
authors.initials: AL
authors.lastname: Rothman
authors.forename: Darunee
authors.initials: D
authors.lastname: Tannitisupawong
authors.forename: Anon
authors.initials: A
authors.lastname: Srikiatkhachorn
authors.forename: Richard G
authors.initials: RG
authors.lastname: Jarman
authors.forename: Jared
authors.initials: J
authors.lastname: Aldstadt
authors.forename: Ananda
authors.initials: A
authors.lastname: Nisalak
authors.forename: Mammen P
authors.initials: MP
authors.lastname: Mammen
authors.forename: Suwich
authors.initials: S
authors.lastname: Thammapalo
authors.forename: Sharone
authors.initials: S
authors.lastname: Green
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Libraty
authors.forename: Robert V
authors.initials: RV
authors.lastname: Gibbons
authors.forename: Arthur
authors.initials: A
authors.lastname: Getis
authors.forename: Timothy
authors.initials: T
authors.lastname: Endy
authors.forename: James W
authors.initials: JW
authors.lastname: Jones
authors.forename: Constantianus J M
authors.initials: CJ
authors.lastname: Koenraadt
authors.forename: Amy C
authors.initials: AC
authors.lastname: Morrison
authors.forename: Thanyalak
authors.initials: T
authors.lastname: Fansiri
authors.forename: Chusak
authors.initials: C
authors.lastname: Pimgate
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Scott
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D015331:Cohort Studies; D003715:Dengue / Q000175:diagnosis / Q000453:epidemiology* / Q000821:virology; D003716:Dengue Virus / Q000302:isolation & purification*; D005260:Female; D006798:Housing; D006801:Humans; D015994:Incidence; D007223:Infant; D008137:Longitudinal Studies; D008297:Male; D011446:Prospective Studies; D012424:Rural Population; D012574:Schools; D013785:Thailand / Q000453:epidemiology; D013997:Time Factors; D014766:Viremia / Q000175:diagnosis / Q000453:epidemiology* / Q000821:virology