The burden of hospitalized lower respiratory tract infection due to respiratory syncytial virus in rural Thailand.

BACKGROUND: We describe the epidemiology of hospitalized RSV infections for all age groups from population-based surveillance in two rural provinces in Thailand.

METHODS: From September 1, 2003 through December 31, 2007, we enrolled hospitalized patients with acute lower respiratory tract illness, who had a chest radiograph ordered by the physician, from all hospitals in SaKaeo and Nakhom Phanom Provinces. We tested nasopharyngeal specimens for RSV with reverse transcriptase polymerase chain reaction (RT-PCR) assays and paired-sera from a subset of patients with IgG enzyme immunoassay. Rates were adjusted for enrollment.

RESULTS: Among 11,097 enrolled patients, 987 (8.9%) had RSV infection. Rates of hospitalized RSV infection overall (and radiographically-confirmed pneumonia) were highest among children aged<1 year: 1,067/100,000 (534/100,000 radiographically-confirmed pneumonia) and 1-4 year: 403/100,000 (222/100,000), but low among enrolled adults aged≥65 years: 42/100,000. Age<1 year (adjusted odds ratio [aOR]=13.2, 95% confidence interval [CI] 7.7, 22.5) and 1-4 year (aOR=8.3, 95% CI 5.0, 13.9) were independent predictors of hospitalized RSV infection.

CONCLUSIONS: The incidence of hospitalized RSV lower respiratory tract illness among children<5 years was high in rural Thailand. Efforts to prevent RSV infection could substantially reduce the pneumonia burden in children aged<5 years.