title: Dengue infection in children in Ratchaburi, Thailand: a cohort study. I. Epidemiology of symptomatic acute dengue infection in children, 2006-2009.
abstract: BACKGROUND
  There is an urgent need to field test dengue vaccines to determine their role in the control of the disease. Our aims were to study dengue epidemiology and prepare the site for a dengue vaccine efficacy trial.
  
  
  RESULTS
  We performed a prospective cohort study of children in primary schools in central Thailand from 2006 through 2009. We assessed the epidemiology of dengue by active fever surveillance for acute febrile illness as detected by school absenteeism and telephone contact of parents, and dengue diagnostic testing. Dengue accounted for 394 (6.74%) of the 5,842 febrile cases identified in 2882, 3104, 2717 and 2312 student person-years over the four years, respectively. Dengue incidence was 1.77% in 2006, 3.58% in 2007, 5.74% in 2008 and 3.29% in 2009. Mean dengue incidence over the 4 years was 3.6%. Dengue virus (DENV) types were determined in 333 (84.5%) of positive specimens; DENV serotype 1 (DENV-1) was the most common (43%), followed by DENV-2 (29%), DENV-3 (20%) and DENV-4 (8%). Disease severity ranged from dengue hemorrhagic fever (DHF) in 42 (10.5%) cases, dengue fever (DF) in 142 (35.5%) cases and undifferentiated fever (UF) in 210 (52.5%) cases. All four DENV serotypes were involved in all disease severity. A majority of cases had secondary DENV infection, 95% in DHF, 88.7% in DF and 81.9% in UF. Two DHF (0.5%) cases had primary DENV-3 infection.
  
  
  CONCLUSIONS
  The results illustrate the high incidence of dengue with all four DENV serotypes in primary school children, with approximately 50% of disease manifesting as mild clinical symptoms of UF, not meeting the 1997 WHO criteria for dengue. Severe disease (DHF) occurred in one tenth of cases. Data of this type are required for clinical trials to evaluate the efficacy of dengue vaccines in large scale clinical trials.
authors.affiliation: Department of Tropical Pediatrics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. arunee.sab@mahidol.ac.th
authors.forename: Arunee
authors.initials: A
authors.lastname: Sabchareon
authors.forename: Chukiat
authors.initials: C
authors.lastname: Sirivichayakul
authors.forename: Kriengsak
authors.initials: K
authors.lastname: Limkittikul
authors.forename: Pornthep
authors.initials: P
authors.lastname: Chanthavanich
authors.forename: Saravudh
authors.initials: S
authors.lastname: Suvannadabba
authors.forename: Vithaya
authors.initials: V
authors.lastname: Jiwariyavej
authors.forename: Wut
authors.initials: W
authors.lastname: Dulyachai
authors.forename: Krisana
authors.initials: K
authors.lastname: Pengsaa
authors.forename: Harold S
authors.initials: HS
authors.lastname: Margolis
authors.forename: G William
authors.initials: GW
authors.lastname: Letson
mesh_terms: D000293:Adolescent; D000914:Antibodies, Viral / Q000097:blood; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003715:Dengue / Q000453:epidemiology* / Q000473:pathology*; D003716:Dengue Virus / Q000302:isolation & purification*; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D015994:Incidence; D008297:Male; D011446:Prospective Studies; D012367:RNA, Viral / Q000097:blood; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012720:Severity of Illness Index; D013785:Thailand / Q000453:epidemiology
chemical_list: D000914:Antibodies, Viral; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D012367:RNA, Viral