Acute diarrhoea and asymptomatic infection in Chilean preschoolers of low and high socio-economic strata.

Preschoolers who belonged to the high (Group I, n = 112) or the low (Group II, n = 90) socio-economic stratum were followed prospectively for six months. Mean monthly incidence of diarrhoea was 3 and 7 episodes per 100 children for Group I and Group II respectively (p less than 0.001). Episodes were shorter and affected a smaller proportion of children in Group I (p less than 0.002 and p less than 0.05), respectively). Bacterial enteropathogens were recovered in 12.6% and 13.5% of the episodes in Group I and Group II and parasites in 15.4% and 62.8%, respectively. Rotavirus was detected once in each group. Asymptomatic carrier rates for enteropathogenic bacteria were 12.0% in Group I and 7.2% in Group II. The corresponding figures for parasites were 28.2% and 62.8% (p less than 0.001). Nutritional status was normal in all children. These results suggest that socio-economic stratum plays an important role in the characteristics of diarrhoeal illness in the groups which conform the population of the less developed countries. Acute diarrhoea is less frequent in preschoolers living in Santiago than in other developing areas. Rates of asymptomatic infection are high.