Trypanosomes of non-human primates from the National Centre of Primates, Ananindeua, State of Pará, Brazil

Trypanosome infections were sought in 46 non-human primates captured principally in Amazonian Brazil. Twenty-two (47.8) were infected with four Trypanosoma species: T. cruzi, T. minasense, T. devei and T. rangeli. These preliminary results confirmed the high prevalence and diversity of natural infections with trypanosomes in primates from Brazilian Amazon and were the first formal record of simian infections with trypanosomes in the State of Acre. The presence of T. cruzi-like and T. rangeli-like parasites are recorded in four new hosts.

Polymorphism in trypomastigotes of Trypanosoma (Megatrypanum) minasense in the blood of experimentally infected squirrel monkey and marmosets

Experimental infections by Trypanosoma (Megatrypanum) minasense were performed in primates - Saimiri sciureus and Callithrix penicillata - with the objective of searching for morphological variations of the blood trypomastigotes with respect to hosts and time of infection. We carried out morphological and morphometric analysis of blood trypomastigotes. Illustrations are given. Both the squirrel monkey and marmoset became infected after the injection of blood trypomastigotes of T. minasense , although the parasitaemia were briefer in the squirrel monkey. The parasites detected in the later host were narrower and shorter than those found in the inoculated marmoset. In the marmoset, the blood stream parasites derived from culture metacyclic trypomastigotes were considerably smaller than those derived from the inoculation of infected blood. Stronger evidence of polymorphism was found when, at the same time of infection, the blood trypomastigotes found in squirrel monkey had smaller length, body width and the distance from posterior end of the body to the kinetoplast almost four times smaller than the parasite found in the marmoset. Therefore, conflicting results on morphology and morphometry of T. minasense obtained by previous investigators could be due to polymorphism.

Morphological features of trypanosomes from squirrel monkeys from the Brazilian Amazon

A morphometric analysis of blood trypamastigotes identified as Trypanosoma minasense, T. saimirii, and T. rangeli harbored by squirrel mankeys from the Brazilian Amazon was performed. Additionally, morphological and biological comparative analysis were conducted of T. saimirii-like and T. rangeli development forms from haemoculture and xenodiagnosis. Illustrations are given of blood trypomastigotes as well as of developing flagellates in triatomine and axenic culture. Mean values of blood trypomastigotes of T. saimirii differ statistically from those of T. rangeli in only two out of ten morphological characteters measured, and ranges overlapped. The developing forms of T. saimirii-like parasites were essentially identical in both xenodiagnosis and haemoculture to those of T. rangeli. Trypanosomes confirmed as T. rangeli were transmitted to mice by the bites of the great majority of triatomines that fed on T. saimirii-like infected monkeys. We conclude that, based on morphology and on the development in triatomine bugs and haemoculture, T. saimirii should not be considered a distinct species. We therefore propose T. saimirii to be a junior synonym of T. rangeli.

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

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.

The haemoculture of Trypanosoma minasense Chagas, 1908

Trypanosoma minasense was isolated for the first time in blood axenic culture from a naturally infected marmoset, Callithrix penicillata, from Brazil. The parasite grew profusely in an overlay of Roswell Park Memorial Institute medium plus 20 per cent foetal bovine serum, on Novy, McNeal and Nicolle medium (NNN), at 27§C, with a peak around 168 hr. The morphometry of cultural forms of T. minasense, estimates of cell population size and comparative growth in four different media overlays always with NNN, were studied. The infectivity of cultural forms to marmosets (C. penicillata and C. jacchus) and transformation of epimastigotes into metacycliclike forms in axenic culture in the presence of chitin derivates (chitosan) were evaluated.