Acute respiratory infections in day care.

A 16-year, longitudinal study of acute respiratory infections was conducted in a day care center. The incidence of infections peaked in the second six months of life (10 per child per year) and declined thereafter. Fewer than 10% of infections involved the lower respiratory tract. The isolation of respiratory viruses was associated closely with illnesses, and viruses appeared to be the most important causes of respiratory infections. Haemophilus influenzae type b was isolated infrequently and caused no invasive disease. Nontypable H. influenzae and Streptococcus pneumoniae were isolated frequently but were not associated epidemiologically with illnesses. Group A streptococci were isolated with moderate frequency but were not a major problem. Although the data presented are an inadequate basis for firm conclusions, they suggest that the incidence of acute respiratory infections during the first year of life is higher among children in day care centers than among those cared for at home but that the incidence in later years is perhaps lower for children who enter day care as infants and remain in day care through the preschool years.