Epidemiology of viral acute lower respiratory infections in a community-based cohort of rural north Indian children

Background: In India, community-based acute lower respiratory infections (ALRI) burden studies are limited, hampering development of prevention and control strategies. Methods: We surveyed children <10 years old at home weekly from August 2012-August 2014, for cough, sore throat, rhinorrhoea, ear discharge, and shortness of breath. Symptomatic children were assessed for ALRI using World Health Organization definitions. Nasal and throat swabs were obtained from all ALRI cases and asymptomatic controls and tested using polymerase chain reaction for respiratory syncytial virus (RSV), human metapneumovirus (hMPV), parainfluenza viruses (PIV), and influenza viruses (IV). We estimated adjusted odds ratios (aOR) using logistic regression to calculate etiologic fractions (EF). We multiplied agent-specific ALRI incidence rates by EF to calculate the adjusted incidence as episodes per child-year. Results: ALRI incidence was 0.19 (95% confidence interval (CI) = 0.18-0.20) episode per child-year. Association between virus and ALRI was strongest for RSV (aOR = 15.9; 95% CI = 7.3-34.7; EF = 94%) and least for IV (aOR = 4.6; 95% CI = 2.0-10.6; EF = 78%). Adjusted agent-specific ALRI incidences were RSV (0.03, 95% CI = 0.02-0.03), hMPV (0.02, 95% CI = 0.01-0.02), PIV (0.02, 95% CI = 0.01-0.02), and IV (0.01, 95% CI = 0.01-0.01) episode per child-year. Conclusions: ALRI among children in rural India was high; RSV was a significant contributor.