Babesia caballi and Theileria equi in ticks from horses in four Indigenous communities of Costa Rica.

Overview

• This study investigated ticks collected from horses in four Indigenous communities of Costa Rica to identify the tick species present and to detect the presence of two parasites, Babesia caballi and Theileria equi, which cause equine piroplasmosis.
• The research provides the first evidence of these parasites’ DNA in ticks from Costa Rica, highlighting potential tick vectors and the need for ongoing surveillance and control measures.

Background

• Equine Piroplasmosis: A disease affecting horses caused by hemoparasites Babesia caballi and Theileria equi.
• Endemic Region: This disease is known to be common or endemic in Costa Rica.
• Knowledge Gap: Prior to this study, although the disease was known in horses, the presence of these parasites in the tick vectors in Costa Rica had not been documented.

Objectives

• Identify the species and sex of ticks infesting horses in four Indigenous communities in Costa Rica.
• Determine the presence of Babesia caballi and Theileria equi DNA in ticks collected from horses known to be positive for piroplasmosis.

Methods

• Sample Collection: 1,063 ticks were collected from 129 horses across four Indigenous communities.
• Identification: The ticks were identified by species, and their sex was classified.
• PCR Testing: Horses were tested for piroplasmosis using PCR. From the 76 horses that tested positive, 203 ticks were selected and analyzed using nested PCR specifically for the DNA of B. caballi and T. equi.
• Sequencing: Two of the PCR-positive tick samples had their sequencing results compared to GenBank references to confirm the identity of the parasites detected.

Results

• Tick Species Distribution:
  • Dermacentor nitens was the predominant tick species, making up 90.3% of all ticks collected.
  • Amblyomma mixtum represented 9.7% of the ticks.
• Parasite Detection in Ticks:
  • Theileria equi DNA was detected in ticks from 55.3% of the horses that were positive for piroplasmosis.
  • Babesia caballi DNA was only found in ticks that also carried T. equi, indicating coinfection.
  • Sequencing showed 99% similarity to known B. caballi and T. equi sequences from GenBank, validating the PCR results.

Conclusions

• This study provides the first evidence of B. caballi and T. equi DNA in ticks from Costa Rica.
• The tick species Dermacentor nitens and Amblyomma mixtum are identified as potential vectors for transmitting these parasites.
• The findings underline the importance of active surveillance and tick control measures in Indigenous communities to prevent the spread of equine piroplasmosis.
• Although the samples were collected in 2011, the study highlights the need for updated surveillance and vector competence studies to further understand and mitigate these infections.
• The results support the One-Health approach by emphasizing the interconnection between vector control, animal health, and community well-being in Indigenous areas of Costa Rica.

Implications and Future Directions

• Ongoing monitoring of tick species and hemoparasite presence in different regions is essential to manage equine health risks.
• Further research on the competence of Dermacentor nitens and Amblyomma mixtum to transmit these pathogens can help clarify their roles in disease ecology.
• Regular updates to surveillance data are necessary, as vector populations and pathogen prevalence can change over time.
• Implementation of tick control strategies in Indigenous communities could reduce equine infection rates and contribute to animal welfare and economic stability.