Hospitalizations for Acute Lower Respiratory Tract Infection Due to Respiratory Syncytial Virus in Thailand, 2008-2011

Background. Few population-based estimates of the incidence of respiratory syncytial virus (RSV) infection in low-or middle-income countries are available. We describe the incidence and epidemiology of hospitalizations for RSV-associated acute lower respiratory tract infection (ALRI) detected by active population-based surveillance in 2 rural Thailand provinces during 2008-2011. Methods. Patients hospitalized with ALRI were systematically sampled. Consenting patients provided nasopharyngeal swab specimens for RSV testing by real-time reverse-transcription polymerase chain reaction. Results. Of 13 982 enrolled patients hospitalized with ALRI, 1137 (8.1%) were RSV positive. After adjustment for sampling and nonenrollment, the incidence of RSV-associated ALRI hospitalization was 85 cases per 100 000 persons/year. The highest rates occurred among children aged <5 years (981 cases per 100 000 persons/year) and <1 year (1543 cases per 100 000 persons/year). Rates were low among older children and young adults but high among persons aged >65 years (130 cases per 100 000 persons/year). Eight (0.7%) RSV-infected study patients died during hospitalization. Annual RSV hospitalizations peaked during July-October with almost no documented RSV hospitalizations during January-June. Conclusions. Our findings demonstrate the substantial contribution of RSV to global ALRI burden, especially in children aged <5 years and the elderly, and underscore the urgent need for effective prevention measures.