Respiratory syncytial virus infection in children under one year of age hospitalized for acute respiratory diseases in Pelotas, RS

ABSTRACT

INTRODUCTION: Acute respiratory diseases (ARDs) are a major cause of infant morbidity and mortality. OBJECTIVE: The present case-controlled study investigated the hospitalizations by ARDs in children under one year of age and the association with the respiratory syncytial virus (RSV) in za Pelotas, RS. METHODS: All children under one year of age hospitalized due to ARDs from August 1997 to July of 1998 were followed-up in the four hospitals of the city. A standardized questionnaire was applied to the children's mother regarding symptoms of the actual illness in addition to social and demographic variables, nutrition, and previous morbidity. The final diagnosis of ARDs was performed by an arbiter (a pediatrician) based on the hospital records of the children and the data on the questionnaire. Nasopharyngeal secretions were collected for RSV detection by direct immunofluorescence. RESULTS: The study included 650 children and the annual incidence rate of hospital admissions for ARDs was 13.9 percent. Admissions showed a seasonal pattern with most of the hospitalizations occurring from July to October. The main causes of admission were pneumonia (43.7 percent), bronchiolitis (31.0 percent), asthma (20.3 percent), influenza (3.5 percent), otitis media (0.8 percent) and laryngitis (0.6 percent). The overall prevalence of RSV was 30.7 percent, with 40.2 percent in bronchiolitis, 28.6 percent in influenza, 27.4 percent in asthma, 26.3 percent in pneumonia, and 25 percent in otitis media. CONCLUSIONS: The results of the present study confirm the high morbidity of ARDs in childhood and the seasonal pattern of ARDs hospitalizations and their association with RSV infection.