Parasitic infections in villagers from three districts of the Brazilian Amazon.

A survey of intestinal parasites among 827 rural villagers in the Brazilian Amazon revealed that the prevalences of infection with Necator americanus, Trichuris trichiura and/or Ascaris lumbricoides were high. However, the intensities of infection with the two parasites for which there were enough data on intensity for further analysis, N. americanus and T. trichiura, were only low or moderate in each of the three districts studied. Possible reasons for the unusual (but not unique) absence of high intensities include moderately good sanitation, low population densities, the way in which work activities are located geographically, the use of indigenous anthelmintics and the geographical isolation of the communities which provided the subjects. Whether the light to moderate levels of infection observed require intervention is discussed.