Infecção por Sarcocystis em búfalos no estado do Rio Grande do Sul, Brasil

Abstract

Serological tests are often used for the detection of antibodies and are useful both for the evaluation of large numbers of samples and for diagnosis in live animals. Direct examination and molecular testing provide the detection and characterization of species involved in infections but require target tissues, such as the myocardium, to be carried out only after the death of the infected animals. Therefore, the objectives of this study were: (1) to verify the presence of antibodies against N. caninum, T. gondii and Sarcocystis spp. in buffalo from Rio Grande do Sul and (2) to clarify the infection of buffalo by Sarcocystis, as well as to carry out the molecular identification of species that affect these animals in the State. In Chapter 1 of this thesis is presented a study in which serum samples of 220 buffaloes were analyzed for the presence of antibodies, through indirect immunofluorescence reaction (IFAT). Samples with antibody titers greater than or equal to 100 were considered positive for the protozoa studied. A total of 60.5% (133/220) of the buffalo serological samples were positive for at least one of the parasites surveyed. Antibodies to N. caninum, Sarcocystis spp. and T. gondii were found in 36.4% (80/220); 25.5% (56/220) and 16.8% (37/220) of the buffalo, respectively, indicating a higher frequency of N. caninum infection than the other protozoa (p = 0.0133). In the study presented in Chapter 2, myocardial samples were collected 80 buffaloes submitted to microscopic examination, followed by molecular analysis. Microcysts were present in 23.75% (19 of 80) of the samples. Genomic DNA was extracted from the 19 isolates and submitted to PCR. Six readable sequences were obtained after sequencing in both directions, all of which were from Sarcocystis levinei.