ABSTRACT
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.
Subject(s)
Animals , Trypanosoma/classification , Amazonian Ecosystem , Brazil , Saimiri/parasitology , TrypanosomatinaABSTRACT
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.
Subject(s)
Animals , Saimiri/parasitology , Trypanosoma/parasitology , Primate Diseases , Trypanosoma cruzi/parasitologyABSTRACT
In the Saimiri monkey, an experimental host for human malaria, acquired protection against Plasmodium falciparum blood stages depends on the IgG antibody populations developed. In vivo protective anti-falciparum activity of IgG antibodies is correlated with the in vivo opsonizing activity promoting phagocytosis of parasited red bloood cells. In contrast, non protective antibodies inhibit this mechanism by competing at the target level. A similar phenomenon can be and human infection. Anti-cytoadherent and anti-rosette antibodies developed by Saimiri and humans prevent the development of physiopathological events like cerebral malaria which can also occur in this experimental host. Furthermore, transfer to protective human anti-falciparum IgG antibodies into infected Saimiri monkeys exerts an anti parasite activity as efficient as that observed when it is transfered into acute falciparum malaria patients, making the Saimiri an even more attractive host. Studies on the role of immunocompetent cells in the protective immune reponse are still in their infancy, however the existance of a restricted polymorphism of MHC II class molecules in the Saimiri confers additional theoretical and practical importance to this model