Natural Infection by Trypanosoma cruzi in a Dog from Bahia State - Northeast of Brazil

Background: Chagas Disease (CD) is a parasitic anthropozoonosis caused by the Trypanosoma cruzi (T. cruzi), a protozoan transmitted by insects from the Reduviidae family. Several species of wild and domestic animals, humans included, are susceptible, developing acute clinical signals (myocarditis and cardiac arrhythmias) or chronic signals (drop on the performance and syncope) of the disease. In Brazil, the disease in dogs shows variable indexes of occurrence. The present paper describes the natural infection by T. cruzi in a canine living in the city of Barra, in the state of Bahia, Brazil, a region classified as high risk of vulnerability for the CD in the northeast of Brazil.Case: A 9-year-old male dog, non-specific breed, was referred to the clinic the Veterinary Clinic for Small Animals, at the Veterinary Medical Teaching Hospital), at the Federal University of the West of Bahia. Its owner reported the presence of bloody secretion in the penile region. During the physical exam it was possible to observe an increase in the volume of the penis base. All of the animal’s physiological parameters were within normal levels. Blood samples and cytological laminas from the lesioned area were collected and sent to the Laboratory of Veterinary Clinical Pathology in the same institution. The cytological exam showed monomorphic population of great round cells with a round nucleus, condensed chromatin and one to two prominent nucleolus, abundant and slightly basophilic cytoplasm, with multiple stippled vacuoles, thus confirming a Transmissible venereal tumor (TVT) case. With the blood exam one observed a thrombocytopenia, neutrophilia with a deviation on the left and the presence of a trypomastigote form of Trypanosoma sp. in the blood smears. A complete blood sample was sent to the Laboratory of Pathology and Molecular Biology from the Fiocruz-BA (Oswaldo Cruz Foundation in the State of Bahia), being identified by the PCR technique, T. cruzi.Discussion: During the complete blood count, specifically using the blood smear, the microscopic visualization of the trypomastigote form of the Trypanosoma sp., a hemoparasite of filiform aspect, with undulating membrane over the whole body and free flagellum, confirming a case of trypanosomiasis. Such diagnostics had not been considered up to this moment, as the animal did not present any clinic symptomatology that indicated the pathological condition. The high levels of parasitemia presented by the animal, confirmed by the presence of the protozoan in the blood smear, probably indicate the acute phase of the infection, period in which the multiplication and development of the agent is higher, consequently allowing the visualization of the hemoparasite in the lamina. Although the TVT had proved to be the main derogatory factor of sanity and wellbeing of the animal, one calls the attention in this case for the trypanosomiasis, a zoonosis that causes great risk to the sole health, highlighting that the canine species is taken as an important reservoir of T. cruzi, relevant for the maintenance and interaction among the domestic and wild cycles of the Chagas Disease. This is the first report of a canine naturally infected by T. cruzi in the west Region of the State of Bahia. It is, thus, important to emphasize its significance once dogs can be reservoirs of the protozoan, acting in their life cycle and epidemiological chain of the Chagas Disease, enabling the infection of triatomines and humans. Future studies should be done with the purpose of determining the predominance of the agent in the region of the city of Barra, in the State of Bahia.

Medicinal Plants of Chile: Evaluation of their Anti-Trypanosoma cruzi Activity

The extracts of several plants of Central Chile exhibited anti-Trypanosoma cruzi trypomastigotes activity. Most active extracts were those obtained from Podanthus ovatifolius, Berberis microphylla, Kageneckia oblonga, and Drimys winteri. The active extract of Drimys winteri (IC50 51.2 μg/mL) was purifi ed and three drimane sesquiterpenes were obtained: polygodial, drimenol, and isodrimenin. Isodrimenin and drimenol were found to be active against the trypomastigote form of T. cruzi with IC50 values of 27.9 and 25.1 μM, respectively.

Strategies for the isolation and identification of trypanocidal compounds from the Rutales

Crude extracts of Rutales species were tested in vitro against the trypomastigote form of Trypanosoma cruzi at 4 mg/mL, and 20% of them showed significant activity (80%). Their inhibitory activity against the glycolytic enzyme GAPDH from T. cruzi has also been evaluated at the concentrations of 100 and 200 mg/mL. Additionally, the inhibitory activity of 13 purified coumarins were also assayed against T. cruzi-GAPDH. Chalepin was the most active substance with IC50 = 64 mM. The 3D structure of the complex chalepin-enzyme was elucidated by X-ray crystallography, revealing the architecture of the interactions between the inhibitor and the enzyme active site.

Trypanosoma cruziexoantigen is a member of a 160 kDa gene family

During the chronic stage of Chagas disease a 160 kDa antigen appears in the blood of patients and remains detectable many years after the onset of the disease. This antigen is secreted by the trypomastigote form of the parasite while it is undetectable in the epimastigote form. We report here that the chronic 160 kDa exoantigen is encoded by a gene family (CEA 160 family). We describe the cloning and partial nucleotide sequence of a gene (CEA 160–1) belonging to the CEA160 family. Comparison of the gene sequence with other sequences present in the databases revealed homologies with severalTrypanosoma cruzisurface antigens. Highest amino acid identity (59%) was with members of a family containing epitopes that mimic nervous tissues (Van Voorhiset al.1993). Another related group (18–22% amino acid identity) comprises proteins of 85 or 160 kDa sharing an amino acid motif that is conserved among bacterial neuraminidases (Foutset al.1991; Pollevicket al.1991; Kahnet al.1991; Takle & Cross, 1991; Francoet al.1993). The amino acid identities with the different antigens were not homogeneously distributed. Regions of higher identity (40–60%) were grouped in the central region of each protein.

Cytosolic-free calcium elevation in Trypanosoma cruzi is required for cell invasion.

To replicate, the trypomastigote form of Trypanosoma cruzi must invade host cells. Since a role for Ca2+ in the process of cell invasion by several intracellular parasites has been postulated, changes in the intracellular Ca2+ concentration in T. cruzi trypomastigotes and in tissue culture L6E9 myoblasts during their interaction were studied at the single cell level using digital imaging fluorescence microscopy or in cell suspensions by fluorescence spectrophotometry. An increase in cytosolic Ca2+ in T. cruzi trypomastigotes was detected at the single cell level after association of the parasites with the myoblasts. Ca2+ mobilization in the host cells was also detected upon contact with trypomastigotes either at the single cell level or in cells grown in coverslips and exposed to suspensions of trypomastigotes. Pretreatment of the parasites with the Ca2+ chelators quin 2 (50 microM) or bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid (BAPTA, 50 microM) decreased the trypomastigotes' association to myoblasts by approximately 40 and 63%, respectively, thus indicating that an increase in intracellular Ca2+ concentration in the parasites is required for cell invasion in addition to Ca2+ mobilization in the host cells.