R.K.G. Bastos; A.M.C. Meneses; A.C.A. Pereira; F.C.M. Oliveira; C.C.G. Moraes; V.T.M.V.N. Almeida; R.N. Vasconcelos; P.A.S. Dias Neto; M.A. Oliveira; Luz; N.F. Souza; R.F. Andrade; R.S. Andrade; L.H.C. Pereira; A.C.F. Cardoso; D.S. Fragoso; R.B.S. Kuroda; G.S. Oliveira; D.J.S. Lima; A.C.C. Lacreta Junior ; E.R. Branco; B.M.A. Leandro; A.M. Costa; A.A. Imbeloni
Universidade Federal Rural da Amazônia, Instituto da Saúde e Produção Animal, Montese, Belém, Pará, Brazil
Trypanosoma sp. is a flagellate protozoan, digenean, found in the trypomastigote form in blood. It can cause infection in all vertebrate classes, with some pathogenic species to humans and domestic and wild animals (Olsen 1974). The parasite has wide geographical distribution, being responsible for causing disease in areas of tropical climate, especially in Africa and Latin America (Lun & Desser 1995; Silva et al. 2002). T. brucei rhodesiense and T. b. gambiense causes sleeping sickness in humans and other species, such as T. b. brucei, T. congolense, T. vivax and T. evansi causes disease in animals (Sileghem et al. 1994). This parasite has been found in 150 wild animal species and in several of them the infection rate was high, being of particular interest the presence of the flagellate in Didelphis, which by its proximity to urbanized areas can serve as a link between wild and urban cycle of the T. cruzi infection (Think & Szyfres 1977). It is important to mention that the animals belonging to the Order Pilosa (sloths and anteaters), formerly known as Edentata, are included in the South America native fauna, but as T. cruzi is ancient to mammals, probably sloths and anteaters comes from a long co-evolution with T. cruzi different strains (Correa 1998). This association may have created mechanisms for both parasite and host protection and perpetuation. In Brazil, the parasitism by Trypanosoma sp. was discovered in animals called "edentulous" as Bradypus torquatus, Tamandua tetradactyla and Cyclops didactylus (Herrera 1998). This was a wild animal disease that becomes a zoonosis, regardless of animals biological cycle it can be transmitted from man to man. In areas where there is only the wild cycle, human infection is incidental, besides when there are triatomines, the disease is considered endemic or hyperendemic (Think & Szyfres 1977). Animals provide an excellent source of infection for the vectors, for its prolonged parasitemia and high number of trypomastigotes forms in their blood (Think & Szyfres 1977). The most species of Trypanosoma develops in hematophagous arthropod of different orders and families, except species that parasite fish, amphibians and some reptiles, which can be transmitted by leeches (Olsen 1974). In the vertebrate hosts blood, trypanosome have trypomastigote characteristic form, elongated, with post-nuclear kinetoplast and scourge the emerging side of the body, which is like undulating membrane. The amastigote form, present in the vertebrate host tissues, are rounded and have no external scourge; while in invertebrates hosts are found epimastigotes--similar to trypomastigotes, but with juxtanuclear kinetoplast and before the nucleus, and a stage of transition between this and amastigote forms, the spheromastigotes,--circular forms with scourge free (Hoare 1972; Haag et al. 1998). Direct parasitological diagnosis of trypanosomiasis is based on the trypomastigotes forms detection in fresh blood samples or blood smear by microscopic examination. Preparations stained allow morphological characterization of the parasite, while fresh examinations facilitate the parasite detection by its motility, which is used for diagnosis in the acute phase, when large numbers of parasites are present in the bloodstream (Chiari 1992). Thus, concentration methods increases the likelihood of detection of parasitemia in the chronic phase (Woo 1969). Among them, the easiest method is the blood containing anticoagulant centrifugation in capillary tubes for microhematocrit, and parasites visualization on the leukocyte layer (Woo 1969). This study is justified because of the shortage of publications mentioning the presence of sloths parasitized by Trypanosoma sp. and the importance of understanding natural foci represented by wild reservoirs and vectors.
Materials and Methods
This study used 18 Bradypus variegatus from various areas of the Para State, Brazil, seized in operations of IBAMA and the Environmental Pará State Military Police. Were collected blood samples in tubes containing anticoagulant (EDTA), from the external jugular vein, then was realized a blood smear to research the parasite. Blood was sent to the Veterinary Clinical Pathology Laboratory of the University of Amazon (UFRA) for processing immediately. The blood smears were stained by rapid staining hematological "Panótico" method and examined in light microscope on the immersion lens.
Of the 18 slides examined, 16 were parasitized with structures compatible with the trypomastigote form of Trypanosoma sp, accounting for 88.8% of positivity.
Discussion and Conclusion
In this study were observed a high occurrence of animals parasitized with trypomastigote form of Trypanosoma sp. These parasites had narrowed extremities, body-shaped C, kinetoplast little colored and sometimes absent, and not visible by the scourge free preparation, similar to the findings of Almeida (2006), which found similar structures in Caiman yacare, characterizing it as the trypomastigote form of Trypanosoma sp. Trypanosomiasis researches in domestic and wild animals from Pantanal, Brazil, have been developed by Nunes & Oshiro (1990) showing the occurrence of flagellate in dogs, coat and capybaras. There was not possible to make accurately parasite identification, because, unlike the human disease-causing species of the genus Trypanosoma, for which parameters for their taxonomic classification is broad and clearly defined by the scientific community, the trypanosome exclusive of domestic and wild animals, and trypanosomatids of plants and insects are still poorly studied. These have been arbitrarily classified as new or old species, adopting is the host of origin and / or geographical origin as a criterion for taxonomic assignment of specific names (Woo & Black 1984; Overath et al. 1999). The infected animals had no clinical symptoms characteristic of trypanosomiasis, so it can suggest they serve as possibility reservoir of the parasite, as described by Instituto Oswaldo Cruz (2008). Further studies are necessary, especially trying to identify more specifically the parasites species found in animals in this research, as well as better understand the epidemiology of the disease in relation to the true role of Bradypus variegatus in the common disease maintenance and transmission to wild and domestic animals, and humans.
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