PEDIATRIC HOSPITALIZATIONS FOR CROUP (LARYNGOTRACHEOBRONCHITIS) - BIENNIAL INCREASES ASSOCIATED WITH HUMAN PARAINFLUENZA VIRUS-1 EPIDEMICS

Group is a common manifestation of respiratory tract infection in chil dren, and human parainfluenza virus 1 (HPIV-1) is the agent most commo nly associated with croup. In the United States, HPIV-1 produces a dis tinctive pattern of biennial epidemics of respiratory illness during t he autumn months of odd-numbered years. National Hospital Discharge Su rvey data for croup hospitalizations among patients <15 years old betw een 1979 and 1993 were examined along with laboratory-based surveillan ce data on HPIV-1 activity in the United States, The mean annual numbe r of croup hospitalizations was 41,000 (range, 27,000-62,000/year). Ni nety-one percent of hospitalizations occurred among children <5 years of age, Minor peaks in croup hospitalizations occurred each year in Fe bruary, and major peaks occurred in October of odd-numbered years, coi ncident with peak HPIV-1 activity, Each biennial epidemic of HPIV-1 wa s associated with 18,000 excess croup hospitalizations nationwide.