Epidemiology of respiratory syncytial virus infection among infants over three winter seasons.

A study involving respiratory syncytial virus was carried out on infants and young children hospitalised with acute respiratory tract infection over the period December 1987 to March 1990. During peak periods of RS virus activity 420 naso-pharyngeal aspirates were submitted to the Virus Reference Laboratory, Department of Medical Microbiology, U.C.D., mostly from the Dublin region. Using immunofluorescence, enzyme linked immunosorbent assay and cell culture techniques 206 samples (49%) were identified as positive for RS virus. Over the period of study RS virus seasonal activity was confined to the winter months October to March with peaks of activity occurring during March 1988, December 1988 and January 1990. Bronchiolitis was the most common clinical manifestation of infection accounting for 48% of the total number of positive results. Eighty two point five per cent of positive detections were reported from infants less than or equal to 6 months old and particularly from infants in the 1-2 month old age group. More males than females were found to be affected by RS virus infection.