Caracterização de surtos de infecção natural por Trypanosoma vivax em bovinos: aspectos clínicos, epidemiológicos e tratamento

Abstract

CAYMMI, L.G. Characterization of natural Trypanosoma vivax infection outbreaks in cattle: clinical, epidemiological and treatment aspects. Salvador, 2022, 121p. Dissertação (Mestre em Ciência Animal nos Trópicos) - Escola de Medicina Veterinária e Zootecnia - Universidade Federal da Bahia, 2022. Bovine trypanosomiasis represents an important hemoparasitosis and the main etiological agent in South America is Trypanosoma vivax, a protozoan transmitted by vector insects, contaminated objects and transplacentally, which is disseminated throughout all Brazilian states, and causes significant economic impacts on cattle, especially in dairy cattle. In the State of Bahia, information about the occurrence of trypanosomiasis is scarce and the clinical and epidemiological aspects are little known. Thus, the objective of this work was to describe the clinical and epidemiological characteristics and the effect of the treatment of bovine trypanosomiasis outbreaks in dairy herds monitored in the State of Bahia. Two technical visits (V1 and V2) were carried out in five rural properties, for the diagnosis of the outbreak and monitoring of the animals after treatment with two applications of isometamidium chloride. Clinical and epidemiological data were obtained with the help of a questionnaire applied to the owners and collaborators of the farms, and by the clinical evaluation of the animals. Blood samples were collected for parasitological diagnosis by the Woo test, hematological and serum biochemistry evaluation, and T. vivax DNA identification by conventional PCR. Only samples examined in V1 were positive to the direct parasitological test and represented 36.4% (35/96) of the samples collected on this occasion. The evaluation by cPCR identified the genetic material of the agent in 68% (66/96) of the samples collected in V1 and in 19% (27/136) of those collected in V2, totaling 40% (93/232) of the samples surveyed. The raising of dairy cattle, the commercialization of animals without sanitary control and the sharing of contaminated needles were the epidemiological characteristics common to all trypanosomiasis outbreaks studied. The clinical changes observed frequently occur in animals infected for the first time and were nonspecific and variable, mainly related to anemia, sudden drop in milk production, weight loss, abortions, neurological disorders and death. Hematological examinations of sick animals evaluated in V1 indicated normocytic normochromic anemia and leukocytosis with regenerative left shift and lymphocytosis. Biochemical tests revealed hyperproteinemia with hyperglobulinemia and hypoalbuminemia, in addition to hypercholesterolemia and increased serum GGT activity. The gradual regression of clinical xiii signs after treatment demonstrated that the drug helped to control the disease, even though the identification of the agent's DNA can still occur in molecular tests, which allow indicating the presence of the agent, but should not be used alone to indicate the disease