EPIDEMIOLOGY OF RESPIRATORY SYNCYTIAL VIRUS INFECTION IN WASHINGTON, D.C.

Abstract

The occurrence of RSV infection and disease was examined with respect to patient age, immunologic status, race and sex. The peak incidence of RSV bronchiolitis and pneumonia was observed at 2 months of age. Thereafter the incidence of these diseases decreased with increasing age, more rapidly for bronchiolitis than for pneumonia. Each of 75 patients who had RSV bronchiolitis or pneumonia during the first 3 months of life possessed neutralizing antibody in his serum during the acute phase of illness. In most instances the level of this antibody, presumably of maternal origin, was moderately high. In contrast, 15 of 57 infants who developed RSV bronchiolitis at 4–7 months of age lacked detectable antibody in their acute phase serum. This finding casts some doubt upon the essential role of serum antibody in RSV bronchiolitis. The serum CF antibody response to RSV was impaired in infants 1–3 months of age. The level of acute phase serum neutralizing antibody was inversely related to the height of the serum complement-fixation antibody response during convalescence, suggesting that maternally derived antibody may have suppressed the immunologic response of some infants. The clinical consequences of RSV infection in infancy did not appear to be influenced by race. The same proportion of males and females with respiratory tract disease yielded RSV; however, significantly more boys were admitted to the hospital for RSV pneumonia, bronchiolitis, croup and pharyngitis-bronchitis.