The parasite that causes simian malaria in the Brazilian
Amazon, Plasmodium brasilianum, is infective to man. In this
region, where humans live within and in close proximity to the
forest, it was suspected that this parasite could be the cause
of a zoonosis. A study was performed in the areas surrounding two
hydroelectric plants in the Amazon, Balbina and Santuel, aiming
at determining the zoonotic potential of this parasite. P.
brasilianum was detected in, respectively, 15.8% and 9.9% of 126
and 252 primates belonging to seven and eight species examined
from Balbina and Samuel. The highest malaria infection rates
were found among the red-howler monkey Alouatta seniculus
straminea (32.3 %), the bearded-saki Chiropotes satanas
chiropotes (50%) and the spider-monkey Ateles paniscus paniscus
(2[1+])from Balbina and in the squirrel-monkey Saimiri ustus
(21%) and the blackfaced-spider-monkey Ateles paniscus chamek
(28.6%)from Samuel.