Background: Respiratory syncytial virus (RSV) is the most frequent cause of hospitalization in infants worldwide; the majority of disease burden is in resource-limited settings. The clinical presentation and illness characteristics of RSV infection in young infants are not well-described in populations where access to health care facilities are limited.
Methods: As part of a randomized clinical trial of maternal influenza immunization in rural southern Nepal, infants were enrolled at birth and maternal and infant assessments were performed at a home visit shortly after birth. Infants were subsequently followed to six months of age with active weekly home-based surveillance for afebrile and febrile respiratory illness. A mid-nasal swab was taken and tested for RSV by RT-PCR for all illness episodes.
Results: 327 (9%) of 3645 infants had a primary RSV illness episode, with 103 (32%) illnesses occurring at < 2 months of age. RSV was highly seasonal, with a peak between September and November over 3 seasons. Approximately half (n=184; 56%) of 327 infants with RSV were male. 76 (28%) of 274 were low birthweight, as compared to 505 (21%) of 2426 infants without RSV. No relationship was found between age at illness and birthweight (R2=0.0; P=0.32; Figure 1). As compared to older infants, infants with RSV at < 2 months of age had similar frequency of cough (88% vs. 86%; P=0.61), fever (63% vs. 56%; P=0.22), wheezing (61% vs. 65%; P=0.50) and total symptom duration (5.2 vs. 5.0 days; P=0.59). Two (0.01%) infants with RSV infection died.
Conclusion: RSV caused a significant burden of respiratory illness in infants under age six months in rural Nepal, although mortality was low. Symptoms of RSV illness in younger and older infants were similar. In designing interventional trials in resource-limited settings, studies should consider clinical and virological endpoints other than hospitalization and mortality.
Glaxo Smith Kline:
J. Tielsch, None
M. C. Steinhoff, None
J. Englund, None
J. Kuypers, None
S. C. Leclerq, None
S. Khatry, None
A. Magaret, None