Background: Elaborate, long-term data on the rhythm, seasonality and severity of the yearly respiratory syncytial virus (RSV) epidemics in Germany are lacking.
Patients and methods: A longitudinal investigation was undertaken of children from birth to 16 years of age admitted with an RSV infection in the two pediatric hospitals in Kiel between July 1994 and June 2001. To compare the severity of the individual seasons, the incidences and the proportion of RSV-positive hospitalized children aged 0 to 2 years from the denominator area of Kiel were compared.
Results: During the 7-year period, the nasopharyngeal aspirates of 2,367 children were investigated; RSV was detected in 384 (16.2%). The seasons from 1994/95 to 1996/97 started late (December to January) and ended between March and May. Since 1997/98 it seems that a late season is followed by an early season (start in September to October) in a 2-year pattern.
Conclusion: No fixed rhythm of the RSV season can be identified as yet. Ascertainment bias is unlikely to explain the differences in rhythm. The incidence of RSV-positive hospitalizations seems to be increasing.