The Epidemiology of Respiratory Syncytial Virus Lower Respiratory Tract Infections in Children Less than 5 Years of Age in Indonesia

Background: Although the epidemiology of respiratory syncytial virus (RSV) lower respiratory tract infections (LRI) is well known in industrialized countries, the burden in developing Asian countries is not well studied. Methods: To define the burden of RSV disease in children < 5 years of age in rural and urban Indonesia, infants and children were enrolled from peri-urban and rural subdistricts, in the following 2 cohorts: (a) a cross-sectional cohort of approximately 100 children from each of 2 subdistricts in the following 5 age groups: 3 to 5, 6 to 8, 9 to 11, 12 to 23, and 24 to 48 months; (b) a birth cohort of all newborns in both subdistricts during the 28 months of the study. All subjects were visited weekly at home. Children with World Health Organization-defined LRI or wheezing had a nasal wash for detection of RSV using an enzyme immunoassay and polymerase chain reaction. Results: Of the 2014 children studied, 1074 were in the cross-sectional and 940 in the newborn cohorts. Of the 802 episodes of LRI, 163 were caused by RSV. The RSV LRI incidence per 1000 child-years (C-Y) was higher in rural areas (57.25 vs. 38.54), P < 0.05. No RSV LRI occurred in the first 2 months of life and the peak incidence was in the 6- to 8-month-old infants (103/1000 C-Y). The rates were lowest in those < 6 months, 16.5 per 1000 C-Y, compared with 83.1 per 1000 C-Y in those 6 to 11 months of age (P < 0.001), 66.99 in those 12 to 23 months of age, and 28.1 in 2- to 5-year-olds. Conclusions: In Indonesia, the incidence of RSV LRI in the first 6 months of life is relatively low with most disease occurring in older children.