The infection rates of trypanosomes in squirrel monkeys at two sites in the Brazilian Amazon

RESUMO

A study was conducted to determine the prevalence of natural infections by trypanosome species in squirrel monkeys Samiri sciureus (Linnaeus) and Samiri ustus (Geoffroy) caught repectively 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 smears (BS), haemocultures and xenodiagnosis 112 monkeys, 67.9 per cent (being 52.7 per cent 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 per cent). Trypanosoma (Megatrypanum) minasense Chagas in 55 (33.3 per cent). Trypanosoma (Herpetosoma) saimirii Rodhain or T. saimirii-like parasites in 53 (32.1 per cent) and Trypanosoma (Schizotrypanum) cruzi Chagas in 17 (10.3 per cent). 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.