Risk factors related to seropositivity for Leptospira spp. in horses in the Serra Catarinense region

ABSTRACT: Leptospirosis is a zoonotic infectious disease caused by the bacterium Leptospira spp. The consequences of infection in horses are unclear, and the serogroups involved vary depending on the region. This study aimed to evaluate the seropositivity of unvaccinated horses in the Serra Catarinense region and the possible risk factors associated with the infection. We used 207 horses from 26 properties, with no clinical history of infection and unvaccinated for leptospirosis. We submitted serum samples to the microscopic agglutination serum (SAM) to obtain the main reference serogroups. We considered animals with titre ≥100 as infected. The results of the serology revealed seropositivity in 45.4% (94/207) of the animals studied. The most frequent antibodies reportedwere those against the serogroups Australis 16.9% (35/207), Ichterhaemorrhagiae 14.4% (30/207), and Grippotyphosa 5.31% (11/207). Among the primary risk factors associated with the infection we reported extensive rearing system (OR = 1.27; P<0.05) and the presence of other animal species such as cattle (OR = 3.85; P<0.01) and capybaras (OR = 2.07; P=0.06). The findings presented in this study showed that leptospirosis is endemic in horses in the Serra Catarinense region, and revealed the need for emergency surveillance and control measures specific to this important zoonosis.

摘要：钩端螺旋体病（Leptospirosis）是由钩端螺旋体属（Leptospira spp.）细菌引发的人畜共患传染病。目前马匹感染该病后的临床转归尚未明确，且其所涉及的血清群存在显著地域差异。本研究旨在评估卡塔林塞山地（Serra Catarinense）地区未接种钩端螺旋体病疫苗的马匹血清阳性率，以及与该感染相关的潜在危险因素。本研究共纳入来自26个养殖场地的207匹马匹，所有受试马匹均无钩端螺旋体感染临床病史，且未接种针对该病的疫苗。我们采用显微镜凝集血清试验（microscopic agglutination serum, SAM）对血清样本进行检测，以确定主要参考血清群；将抗体滴度≥100的受试个体判定为感染阳性。血清学检测结果显示，受试马匹的总体血清阳性率为45.4%（94/207）。检出频率最高的抗体对应的血清群依次为Australis群（16.9%，35/207）、出血性黄疸血清群（Icterohaemorrhagiae，14.4%，30/207）及流感伤寒血清群（Grippotyphosa，5.31%，11/207）。与感染显著相关的主要危险因素包括：粗放饲养模式（比值比OR=1.27；P<0.05），以及养殖场地共存其他动物物种，如牛（OR=3.85；P<0.01）和水豚（OR=2.07；P=0.06）。本研究结果证实，卡塔林塞山地地区的马匹群体中钩端螺旋体病呈地方性流行，提示亟需针对这一重要人畜共患病制定并实施专项监测与防控措施。