Epidemiologic studies among Amerindian populations of Amazônia. I. Pyoderma: prevalence and associated pathogens.

Pyoderma was studied among a representative sample of the residents of four remote Amerindian villages, Amazonas State, Brazil, during July-August 1976. The overall prevalence among the 775 inhabitants examined was 11%, with little intervillage variation. When the attack rates for the entire sample population were calculated by 5-year age intervals, the 0- to 4-year-olds had the highest rate, 31%. The highest prevalence, 38%, was found among 3-year-olds. Attack rates were not apparently related to sex. Cultures which were taken from representative pyoderma lesions from people in the four survey villages and from three additional villages were studied by a modified delayed culture technique for recovery of gram-positive pathogens from silica-gel desiccated swabs. Group A and group G B-hemolytic streptococci, coagulase positive Staphylococcus aureus, and Corynebacterium diphtheriae were isolated. Group A S. pyogenes was most commonly found, occasionally as the sole pathogenic species. No nephritogenic M-types were found, although most isolates were not M-typable. The T-types found corresponded to those previously reported as being pyoderma-associated. Most pyoderma-associated C. diphtheriae isolates were non-toxigenic. Biotypes gravis and mitis were equally represented.