We report the result of an examination for blood and intestinal protozoa in 12 specimens of the red squirrel Sciurus spadiceus
(Rodentia: Sciuridae) from Birroque, municipality of Plácido de Castro, state of Acre, Brazil. No parasites were detected in thin, Giemsa-stained blood films of the animals, but culture of the blood of three in Difco B45 medium blood-agar slants gave rise to isolates of epimastigotes. Inoculation of one isolate into laboratory mice resulted in the appearance of Trypanosoma cruzi
-like trypomastigotes in their peripheral blood, and the other two isolates gave rise to transient infections with a T. lewisi
-like parasite in inoculated mice and hamsters. The failure of the latter parasite to develop in the triatomine bug Rhodnius robustus suggests that it is probably not T. rangeli
. This appears to be the first record of a T. lewisi
-like trypanosome in neotropical squirrels. Oocysts of an Eimeria
sp., were detected in the faeces of 10 animals (83.3%). The parasite develops in the epithelial cells of the intestine, where it may cause severe damage and sometimes results in death of the animal. No oocysts were detected in bile.