Comparison of Seroprevalence and Identification of Risk Factors for Theileria equi in Horses From Vector-Free and Infested Areas in Southern Brazil.

The research aims to compare the prevalence of antibodies for the tick-borne pathogen Theileria equi in horses from tick-free areas and tick-infested areas in southern Brazil. Besides, it seeks to identify potential risk factors for exposure to this pathogen.

Overview of the Research

The study focuses on the Theileria equi, a parasite that causes equine piroplasmosis, a disease in horses. In South America, three tick species are associated with this disease: Dermacentor nitens, Amblyomma sculptum, and Rhipicephalus microplus. However, in the Rio Grande do Sul state of Southern Brazil, only R. microplus is present, and it also houses an area legally free of R. microplus.

Methodology

• The researchers worked on farms in a tick-free area (23 farms, 215 horses) and a tick-infested area (25 farms, 141 horses).
• They collected blood samples from 356 horses across both areas and then conducted an indirect enzyme-linked immunosorbent assay to detect anti-T. equi antibodies.
• The team additionally conducted questionnaires and interviews to pinpoint potential risk factors.

Key Findings

• The seropositivity rate for T. equi was significantly different – 6% in the tick-free area compared to 70% in the tick-infested area.
• Horses that had visibly had ticks had four times the chance of being seropositive for T. equi.
• The odds were thrice as high if ticks were observed on cattle sharing paddocks with horses on the farm.

These findings highlight the significant role of R. microplus ticks in the epidemiology of T. equi. The stark seroprevalence imbalance between tick-infested and free areas underscores the pathogen’s vulnerability to ticks.

Implications

According to the research, there is significant potential for establishing a T. equi-free zone for horse breeding in Southern Brazil. By maintaining such areas free from tick infestations, it would considerably reduce the risk of horses contracting T. equi, benefiting the equine industry. Further studies could focus on other possible risk factors and mitigating techniques.