Detection and molecular characterization of Trypanosoma (Duttonella) vivax in dairy cattle in the state of Sergipe, northeastern Brazil

Abstract Trypanosoma (Duttonella) vivax is an important cause of economic losses among feedlot cattle. These losses are related to the morbidity, mortality, reproductive issues and decreased production. It is known that the clinical signs observed in infections by this protozoon are similar to other hemoparasitosis, which difficult the diagnosis. Therefore, the aim of this study was to detect and molecularly characterize an outbreak of trypanosomiasis caused by T. (D.) vivax in dairy cattle in the municipality of São Miguel Aleixo, state of Sergipe, Brazil. Blood samples from cattle (n = 15) presenting clinical signs compatible with trypanosomiasis were collected and parasitological and molecular evaluated. Among the samples analyzed, 34% (5/15) were positive from blood smears, 60% (9/15) from the buffy coat method and 80% (12/15) from the molecular method. The DNA sequence obtained (659 bp) showed 99% similarity to T. (D.) vivax sequences that are available in the GenBank database. The presence of this protozoon in cattle herds is a problem for producers. Diagnosing trypanosomiasis is problematic because its evolution is similar to that of other parasitic blood diseases. In addition, this is the first report of infection by T. (D.) vivax in cattle in the state of Sergipe, northeastern Brazil.

摘要：间日锥虫（Trypanosoma (Duttonella) vivax）是导致育肥牛场蒙受重大经济损失的重要病原体，此类经济损失与患病牛的发病率、死亡率、生殖障碍以及生产性能下降密切相关。已知该原生动物感染引发的临床症状与其他血液寄生虫病高度相似，这给临床诊断带来了极大阻碍。为此，本研究旨在对巴西塞尔希培州圣米格尔阿莱克苏市奶牛场暴发的由T. (D.) vivax引起的锥虫病开展分子检测与分型鉴定。本研究采集了15头表现出疑似锥虫病临床症状的奶牛血液样本，进行寄生虫学与分子生物学检测。分析结果显示：血涂片法阳性率为34%（5/15），血沉棕黄层法阳性率为60%（9/15），分子生物学方法阳性率为80%（12/15）。本研究获得的DNA序列（长度659 bp）与基因银行（GenBank）数据库中已收录的T. (D.) vivax序列同源性达99%。牛群中该原生动物的感染对养殖户构成了严重困扰，且由于其临床病程与其他血液寄生性疾病相似，锥虫病的诊断始终存在难度。此外，本研究为巴西东北部塞尔希培州首次报道牛感染T. (D.) vivax的案例。