Aspectos epidemiológicos de Theileria equi, Babesia caballi e Borrelia spp. em equinos de uso militar das regiões Sudeste e Sul do Brasil

Abstract

In order to assess the epidemiological aspects of the occurrence of Theileria equi, Babesia caballi and Borrelia spp. in horses kept in military units in Rio de Janeiro and Rio Grande do Sul states, blood samples and ticks were collected. In all samples of DNA extracted from blood of horses the occurrence of infection by T. equi and B. caballi were investigated by PCR. In the serum samples, was assessed by ELISA, the occurrence of anti T. equi, B. caballi and Borrelia spp. The occurrence of Amblyomma sculptum, Dermacentor nitens and Rhipicephalus (Boophillus) microplus was assessed at different levels of infestation. From the analyzed serum, 82.07% (n = 389/474) were considered positive for T. equi, and a higher prevalence was observed in horses from the “Coudelaria do Rincão”, in Rio Grande do Sul state (87.33%, n = 262/300). In horses kept at the Agulhas Negras Military Academy, in Rio de Janeiro state, a prevalence of 72.99% (n = 127/174) was observed. Multivariate analysis showed that the factor “origin” of the horses stabled at Coudelaria do Rincão was the most influential factor associated to seropositivity of animals (p <0.05; OR = 2.89, CI: 1.34 to 6.19 ), and that grazing with cattle was associated with the presence of the species R. microplus. PCR assay showed the presence of T. equi DNA in 49.37% (n = 234/474) of the tested blood samples, confirming these animals as asymptomatic carriers. Regarding serology for B. caballi, there was a prevalence of 59.92% (n = 284/474), with the highest frequency in the animals of the Southeast (72.99%, n = 127/174) in comparison to those created in the South region (52.33%, n = 157/300). It was found that remaining in the Southeast region was the most influential factor for seropositivity (p <0.05; OR = 3.12, CI: 1.80 to 5.40). We detected the presence of B. caballi DNA at 0.21% (n = 1/474) of the tested blood samples, demonstrating a low circulation rate of these agents in the livestock. Regarding the serology for Borrelia spp., a prevalence of 39.24% (n = 186/474) was found, with the highest frequency in the South herd, with 44.66% (n = 134/300), in comparison to the Southeast herd (29.88%, n = 52/174). Females (p <0.05; OR = 1.96, CI: 1.25 to 3.08) with less than 5 years on the property (p <0.05; OR = 2.67; CI: 1, 14 to 6.26) originated from “Coudelaria do Rincão” (p <0.05; OR = 2.33, CI: 1.17 to 4.62) associated with grazing with cattle and the presence of the tick R. microplus were the most related factor to seropositivity. With regards to T. equi, it was found that the evaluated military herds have an endemic infection, with high prevalence of asymptomatic animals. With respect to B. caballi, it was found that this agent exhibits low circulation at the investigated herds. Evidence of Borrelia circulation with seroprevalence in horses reinforces its role as sentinels, as alert factor for potential occurrence of human cases. These results support the importance of epidemiological surveillance of vector ticks and their association with agents of risk to the health of the military personnel and herds, in the evaluated areas.