Prevalence and Risk Factors Associated With Natural Infection by Trypanosoma evansi in Campeiro Horses.

Campeiro horse is a breed locally adapted to the Santa Catarina plateau region and its main characteristic is the gait, it is known as "Marchador das Araucárias." It is a breed considered in danger of extinction, being fundamental the search for the preservation of this important genetic resource. Surra, caused by the protozoan Trypanosoma evansi, is among the diseases that affect horses. However, there are no data on the prevalence of infection in Campeiro horses. This study aimed to determine the prevalence of T. evansi in Campeiro horses, correlate hematology and serum biochemistry, and identify possible risk factors. Blood samples were collected by venipuncture of 214 Campeiro horses, 50 males and 164 females, aged between 3 months and 27 years, from 16 properties located in the States of Santa Catarina, Rio Grande do Sul, and Paraná. An epidemiological questionnaire was carried out with the owners to analyze the associated risk factors. The blood samples were submitted to polymerase chain reaction, immunofluorescence antibody test, complete blood count, and serum biochemistry. The prevalence was 14% of positive animals by polymerase chain reaction and 59% by immunofluorescence antibody test . There was an increase in hematocrit, and in the number of basophils, a decrease in plasmatic fibrinogen, and in the enzymatic activity of alanine aminotransferase, aspartate aminotransferase, and urea, and an increase in creatine phosphokinase and creatinine in positive animals, which is possibly unrelated to the infection. The data obtained through the epidemiological questionnaires showed no difference. Therefore, T. evansi is present in the South of Brazil, with a high prevalence in Campeiro horses.