A study was conducted to determine the prevalence of natural infections by
trypanosome species in squirrel monkeys: Saimiri sciureus (Linnaeus) and
Saimiri ustus (Geoffroy) caught respectively near 2 hydroelectric plants:
Balbina, in the State of Amazonas, and Samuel, in the State of Rondonia,
Brazil. A total of 165 squirrel monkeys were examined by thick and thin
blood smears (BS), haemocultures and xenodiagnosis: 112 monkeys,
67.9%,(being 52.7% with mix infections) were positive to trypanosomes. Four
species of trypanosomes were found in monkeys from the 2 areas: Trypanosoma
(Tejeraia) rangeli Tejera or T. rangeli-like parasites in 58 squirrel
monkeys (35.2%), Trypanosoma (Megatrypanum) minasense Chagas in 55 (33.3%),
Trypanosoma (Herpetosoma) saimirii Rodhain or T. saimirii-like parasites in
53 (32.1%) and Trypanosoma (Schizotrypanum) cruzi Chagas in 17 (10.3%). As
T. saimirii resembles T. minasense in blood-stream trypomastigotes and T.
rangeli in cultural forms and in this survey almost all monkeys presenting
trypanosomes morphologically indistinguishable from T. saimirii and/or T.
minasense in BS were found through xenodiagnosis and/or haemoculture to be
infected by T. rangeli, we suggest that the validity of T. saimirii needs
to be evaluated.
