[Gastroenteritis and acute respiratory infections among children under 5 years old in an area of southeastern Brazil, 1986-1987. I--Acute respiratory infections].

A probabilistic sample of children up to 5 years old was studied (n = 468). The epidemiological survey was carried out in five areas in the municipality of S. Paulo (Brazil), from March 1986 to May 1987. Data were obtained through household interviews once a month during one year. Some of the most relevant socioeconomic characteristics of the children's families are: low family income "per capita"; 29.3% of the parents were migrants with a mean period of residence in S. Paulo city of 18.6 years; 40% of the families had access exclusively to public or philanthropic health care services. Among the children included in the research, 87.3% were eutrophic, 94% were fully vaccinated, 90.6% had never been hospitalized as a consequence of acute respiratory infections (ARI). During the follow up of 1 year, 554 episodes of ARI with mean of 6.8 days of duration were identified. The incidence of ARI was 11.8 episodes per 100 children/month. The most vulnerable age group consisted of children up to one year of age. Thirty six percent of the ARI events were followed by at least one other case in the household. The index case in 53% of these cases were children up to 6 years old. Around 52.6% of the episodes did not require a medical assistance, 46.7% were assisted in ambulatory, 4 cases (0.7%) have had hospital treatment and only one died. The most frequent therapeutical conduct regarding children submitted to medical care assistance was the prescription of antibiotics and expectorants. Some factors related to social economic status and personal background such as living conditions and history of previous respiratory diseases were associated with higher incidence of ARI.