Trachoma and ethnic diversity in the Upper Rio Negro Basin of Amazonas State, Brazil.

A trachoma survey was carried out among three culturally different populations of the Upper Rio Negro Basin in the Brazilian rain forest of Amazonas State. The results indicate that trachoma is prevalent in the region, reaching hyperendemic levels (between 50.9% and 56.4%) in all communities studied. However, the severity of the disease appears to be related to the ethnic origin of the tribes, following the rank of social and cultural values that regulate the complex interactions between the Indian groups of the region.