Molecular investigation of Babesia caballi in horses from the state of Rio de Janeiro, Brazil: Epidemiological aspects associated with the infection.

The research article investigates the epidemiological aspects of Babesia caballi infection in horses from Rio de Janeiro, Brazil, focusing on factors such as the presence and level of tick infestation, breed conditions, and animal management. The study identified young horses bred in low altitude regions with high temperatures, and heavily infested by the Dermacentor nitens tick, as those most likely to be infected by B. caballi.

Study Overview and Methodology

• The researchers collected samples from 516 horses from various farms in Rio de Janeiro, Brazil.
• An epidemiological questionnaire was used to evaluate the presence and level of tick infestation, breed conditions, and animal management on each farm.
• The gene coding for the rhoptry-associated protein-1 (RAP-1) of B. caballi was amplified using nested PCR (nPCR).
• The data was then analyzed and compared to other B. caballi isolates available in GenBank.

Findings

• Of the 516 horses sampled, 89 (or 17.2%) presented B. caballi DNA.
• The gene sequences obtained showed 99-100% similarity with other isolates of B. caballi, based on the RAP-1 gene.
• The research identified key variables associated with B. caballi infection in horses, namely: (1) Age below two years, (2) Farms located in low altitude regions, and (3) infestation by the Dermacentor nitens tick.
• A high level of Dermacentor nitens infestation in horses was also identified as a factor contributing to B. caballi infection.

Conclusion

• Young horses bred in low altitude, high-temperature regions and heavily infested by Dermacentor nitens ticks are more likely to be infected by B. caballi.
• The study significantly indicates that the Dermacentor nitens tick likely serves as the biological vector for B. caballi in the region studied.