Intestinal parasitic infections in young children in Sao Paulo, Brazil: prevalences, temporal trends and associations with physical growth

The prevalences of intestinal parasitic infections were investigated, between 1995 and 1996, in a household-based sample of 1044 children aged < 5 years who lived in the city of Sao Paulo, Brazil. Only 10. 7 % of the children were infected, the most prevalent parasites being Giardia duodenalis (5.5%), Ascaris lumbricoides (4.4%) and Trichuris trichiura (1.0%). A comparison between these data and results from two previous population-based surveys, completed in Sao Paulo in 1974 and 1985, revealed a dramatic decrease in the prevalence of intestinal helminths in this age-group, with less marked changes in the prevalence of Giardia, over the two past decades. Despite the low prevalence of malnutrition (2.4% of stunting and 0.6% of wasting) and intestinal parasites in this population, there was a significant association (P= 0.05, after controlling for potential confounding variables) between helminth (but not Giardia) infection and height. The helminth-infected children had a mean height-for-age z-score of - 0.412 [95% confidence interval (CI) = - 0.637-- 0.186], compared with one of 0.0 15 (CI = - 0.049-0.079) for the non-infected children. No significant relationship between intestinal parasitic infection and children's weight was detected. In conclusion, a small but significant negative relationship between intestinal helminthic infections and children's growth was detected in an urban environment with low prevalences of both intestinal parasitic infection and malnutrition.