Etiology of acute respiratory tract infections among children in a combined community and hospital study in Rio de Janeiro.

We reviewed data collected between January 1987 and December 1989 on the etiology of acute respiratory infections (ARI) among 827 children in two low-income communities and a hospital in Rio de Janeiro. Respiratory syncytial virus was identified in 38% of cases of ARI, influenza A virus in 1%, parainfluenza 3 virus in 1%, and multiple viruses in 1%. Respiratory syncytial virus was most prevalent among hospitalized children, with seasonal increases in the late fall and winter. The principal bacterial pathogens were Staphylococcus aureus, gram-negative bacteria, Streptococcus pneumoniae, and alpha-hemolytic streptococci. Specimens that were most often positive were pleural fluid (46%) and specimens from other normally sterile sites (24%); normally sterile sites included the CSF, trachea, and lungs. Urine counterimmunoelectrophoresis for S. pneumoniae and Haemophilus influenzae polysaccharide antigens was positive in 3% and 2% of cases, respectively. Pharyngeal cultures yielded low numbers of S. pneumoniae and H. influenzae organisms and higher numbers of gram-negative bacteria. This study demonstrates the high incidence of ARI (4.5 cases per 100 child-weeks) among children in Rio de Janeiro and the high morbidity associated with the illness (ARI is responsible for 25%-50% of all pediatric hospitalizations) and the fact that continued attention must be paid to both viral and bacterial agents of ARI.