title: Incidence and etiology of acute lower respiratory tract infections in hospitalized children younger than 5 years in rural Thailand.
abstract: BACKGROUND
  Pneumonia remains a leading cause of under-five morbidity and mortality globally. Comprehensive incidence, epidemiologic and etiologic data are needed to update prevention and control strategies.
  
  
  METHODS
  We conducted active, population-based surveillance for hospitalized cases of acute lower respiratory tract infections (ALRI) among children <5 years of age in rural Thailand. ALRI cases were systematically sampled for an etiology study that tested nasopharyngeal specimens by polymerase chain reaction; children without ALRI were enrolled as controls from outpatient clinics.
  
  
  RESULTS
  We identified 28,543 hospitalized ALRI cases from 2005 to 2010. Among the 49% with chest radiographs, 76% had findings consistent with pneumonia as identified by 2 study radiologists. The hospitalized ALRI incidence rate was 5772 per 100,000 child-years (95% confidence interval: 5707, 5837) and was higher in boys versus girls (incidence rate ratio 1.38, 95% confidence interval: 1.35-1.41) and in children 6-23 months of age versus other age groups (incidence rate ratio 1.76, 95% confidence interval: 1.69-1.84). Viruses most commonly detected in ALRI cases were respiratory syncytial virus (19.5%), rhinoviruses (18.7%), bocavirus (12.8%) and influenza viruses (8%). Compared with controls, ALRI cases were more likely to test positive for respiratory syncytial virus, influenza, adenovirus, human metapneumovirus and parainfluenza viruses 1 and 3 (P ≤ 0.01 for all). Bloodstream infections, most commonly Streptococcus pneumoniae and nontyphoidal Salmonella, accounted for 1.8% of cases.
  
  
  CONCLUSIONS
  Our findings underscore the high burden of hospitalization for ALRI and the importance of viral pathogens among children in Thailand. Interventions targeting viral pathogens coupled with improved diagnostic approaches, especially for bacteria, are critical for better understanding of ALRI etiology, prevention and control.
authors.affiliation: From the *CDC-Hubert Global Health Fellow, Centers for Disease Control and Prevention, Atlanta, GA; †International Emerging Infections Program, Global Disease Detection Regional Center, Thailand Ministry of Public Health-US Centers for Disease Control and Prevention Collaboration, Nonthaburi, Thailand; ‡Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA; §National Institute of Health, Thailand Ministry of Public Health, Nonthaburi, Thailand; ¶Division of Viral Diseases, Centers for Disease Control and Prevention, Atlanta, GA; ‖Nakhon Phanom Provincial Hospital, Nakhon Phanom; **Crown Prince Hospital, Sa Kaeo, Thailand; and ††Division of Global Disease Detection and Emergency Response, Centers for Disease Control and Prevention, Atlanta, GA.
authors.forename: Reem
authors.initials: R
authors.lastname: Hasan
authors.forename: Julia
authors.initials: J
authors.lastname: Rhodes
authors.forename: Somsak
authors.initials: S
authors.lastname: Thamthitiwat
authors.forename: Sonja J
authors.initials: SJ
authors.lastname: Olsen
authors.forename: Prabda
authors.initials: P
authors.lastname: Prapasiri
authors.forename: Sathapana
authors.initials: S
authors.lastname: Naorat
authors.forename: Malinee
authors.initials: M
authors.lastname: Chittaganpitch
authors.forename: Sununta
authors.initials: S
authors.lastname: Henchaichon
authors.forename: Surang
authors.initials: S
authors.lastname: Dejsirilert
authors.forename: Prasong
authors.initials: P
authors.lastname: Srisaengchai
authors.forename: Pongpun
authors.initials: P
authors.lastname: Sawatwong
authors.forename: Possawat
authors.initials: P
authors.lastname: Jorakate
authors.forename: Anek
authors.initials: A
authors.lastname: Kaewpwan
authors.forename: Alicia M
authors.initials: AM
authors.lastname: Fry
authors.forename: Dean
authors.initials: D
authors.lastname: Erdman
authors.forename: Somchai
authors.initials: S
authors.lastname: Chuananon
authors.forename: Tussanee
authors.initials: T
authors.lastname: Amornintapichet
authors.forename: Susan A
authors.initials: SA
authors.lastname: Maloney
authors.forename: Henry C
authors.initials: HC
authors.lastname: Baggett
mesh_terms: D016470:Bacteremia / Q000453:epidemiology / Q000382:microbiology / Q000821:virology; D002675:Child, Preschool; D005260:Female; D006760:Hospitalization; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011014:Pneumonia / Q000453:epidemiology / Q000382:microbiology / Q000821:virology; D012141:Respiratory Tract Infections / Q000453:epidemiology* / Q000382:microbiology / Q000821:virology; D012424:Rural Population; D013785:Thailand / Q000453:epidemiology
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