Frequency and factors associated with Theileria equi, Babesia caballi and Trypanosoma evansi in equids from Bahia (Northeast Brazil)

Abstract The aim of this study was to determine the frequency and factors associated to Babesia caballi, Theileria equi and Trypanosoma evansi in naturally infected equids from the northeast Brazil. Blood samples from 569 equids (528 horses, 8 mules, and 33 donkeys) were collected and tested for the presence of DNA of each of these protozoan parasites by PCR. Generalized linear models were used to evaluate risk factors associated with the infection. The frequency of T. equi infection was 83.5% (475/569) - 84.3% in horses, and 73.2% in donkeys and mules. The results of the final model indicated that age (senior group) and animal species (mule and donkey group) were protective factors against this pathogen. The frequency of B. caballi infection was 24.3% (138/569) - 23.5% in horses and 34.1% in donkeys and mules. Age (adult and senior group) was considered a protective factor against B. caballi infection whereas animal species (donkey and mule group) were considered a risk factor for the infection. Trypanosoma evansi infection was not detected in any of animals. Our results suggest that equids from the area studied may be infected earlier in life with the etiological agents of equine piroplasmosis and become asymptomatic carriers.

摘要 本研究旨在明确巴西东北部自然感染马科动物中，驽巴贝斯虫（Babesia caballi）、马泰勒虫（Theileria equi）及伊氏锥虫（Trypanosoma evansi）的感染频率及其相关影响因素。研究共收集569份马科动物血液样本（其中马528匹、骡8头、驴33头），采用聚合酶链式反应（PCR）检测上述三种原虫的DNA，并通过广义线性模型评估与感染相关的危险因素。结果显示，马泰勒虫总感染率为83.5%（475/569），其中马的感染率为84.3%，骡与驴的感染率为73.2%；最终模型表明，年龄（老年组）与动物种类（骡驴组）为该病原体感染的保护因素。驽巴贝斯虫总感染率为24.3%（138/569），马的感染率为23.5%，骡驴组感染率为34.1%；年龄（成年及老年组）为驽巴贝斯虫感染的保护因素，而动物种类（骡驴组）则是该感染的危险因素。所有受试动物均未检出伊氏锥虫感染。本研究结果提示，该研究区域的马科动物可能在幼年阶段即感染马梨形虫病的病原体，并成为无症状携带者。