Canine ehrlichiosis: prevalence and epidemiology in northeast Brazil

Ehrlichiosis is a zoonotic disease that is caused by bacteria of the genus Ehrlichia. The aims of this study were to detect the presence of Ehrlichia spp. in the blood of dogs in Ituberá, Bahia, and to compare the sensitivities and specificities of blood smear, serological, and molecular examinations. Furthermore, this study identified factors associated with exposure to the agent in dogs in this locality. Blood samples were collected from 379 dogs and submitted for indirect immunofluorescent assay and polymerase chain reaction testing for the detection of Ehrlichia spp. antibodies and DNA, respectively. Additionally, a peripheral blood smear was obtained from the ear tip for parasite identification. Of the 379 animals, 12.4%, 32.7%, and 25.6% were identified as positive on the blood smear, serological, and molecular tests, respectively. The dogs positive in one of the three techniques were considered exposed (46.9%). Younger dogs and rural habitat were protective factors and presence of ticks and contact with other dogs were the risk factors associated with exposure to the agent. It was concluded that dogs of Ituberá have high positivity for Ehrlichia spp. and that the diagnostic methods used for detection are complementary.

埃立克体病（Ehrlichiosis）是由埃立克体属（Ehrlichia）细菌引发的人畜共患病。本研究旨在检测巴西巴伊亚州伊图贝拉（Ituberá）地区犬只血液中的埃立克体属（Ehrlichia spp.）病原，并对比血涂片检测、血清学检测与分子生物学检测的灵敏度与特异性。此外，本研究还明确了该地区犬只接触该病原的相关影响因素。研究共采集379份犬只血液样本，分别采用间接免疫荧光试验（Indirect Immunofluorescent Assay）与聚合酶链反应（Polymerase Chain Reaction, PCR）进行检测，以分别检出埃立克体属抗体与病原DNA；同时从犬只耳尖采集外周血涂片，用于寄生虫鉴定。在379只受试犬只中，血涂片检测、血清学检测与分子生物学检测的阳性率分别为12.4%、32.7%与25.6%。经三种检测技术任意一项呈阳性的犬只被判定为病原暴露阳性，总暴露率达46.9%。分析结果显示，年轻犬只与乡村栖息环境为保护因素，而蜱虫寄生及与其他犬只接触为与该病原暴露相关的危险因素。本研究证实，伊图贝拉地区犬只的埃立克体属病原阳性率较高，且所采用的三种诊断方法具有良好的互补性。