Trypanosoma vivax e Ehrlichia sp. em bovinos leiteiros na microrregião de Feira de Santana, Bahia

Abstract

The protozoan Trypanosoma vivax and the bacterium Ehrlichia sp. are pathogens described in cattle in different regions of Brazil. Scarce information is available for these two microorganisms in cattle in the state of Bahia. The objective of this study, therefore, was to determine the frequency of adult dairy cattle infected by Trypanosoma vivax, as well as the frequency of animals seropositive for Ehrlichia sp., and to confirm infection by this bacteria within the studied population. The thesis is divided in two articles, the first dedicated to the study of T. vivax in cattle, and the second, about the serological frequency and molecular confirmation of Ehrlichia sp. in the same bovine samples tested for T. vivax. Whole blood samples from dairy cattle, aged over one year, were obtained in four municipalities in the Feira de Santana microregion (São Gonçalo de Campos, Santanópolis, Antônio Cardoso and Teodoro Sampaio). The sample number was estimated at 244 cattle. Whole blood samples from 256 adult dairy cattle were collected from 256 adult dairy cattle on farms whose animals were apparently healthy, with no signs of illness or recent deaths. The hematocrit of the blood samples was determined, and almost all of them presented erythrocyte values within the reference values. PCR for T. vivax resulted in 100% negative animals. In contrast, 98.36% of the 256 animals tested were seropositive for Ehrlichia sp. In a molecular evaluation, PCR was performed for Ehrlichia sp. in 40 blood samples from cattle seropositive for Ehrlichia sp. and thirteen animals presented DNA from the bacteria. DNA samples positive for Ehrlichia sp. were submitted for nucleotide sequencing to determine whether cattle are infected by the species Ehrlichia minansensis, which is the only species of Ehrlichia confirmed in cattle in the country. We conclude that, despite T. vivax being detected in animals without clinical series in different regions of Brazil, cattle from the four farms tested and without a history of trypanosomiasis are apparently free of the infection. Conversely, it was found that Ehrlichia sp., which is transmitted by ticks, is present in adult dairy cattle, which probably develop immunity against the bacteria.