Infection dynamics of Theileria equi in carrier horses is associated with management and tick exposure.

The article studies the infection dynamics of Theileria equi, a tick-borne equine parasite, in carrier horses and observes how factors such as management and tick exposure influence the parasitic load. The research suggests that identifying different risk groups can help optimize treatment methods and control practices to minimize disease risks.

Methodology and Findings

• The study collected blood samples from 395 horses at four different time intervals throughout a year, along with information on the horses’ demography, clinical data and associated ticks.
• The presence of Theileria equi and the parasitic load was tested using PCR (Polymerase Chain Reaction) and qPCR (Quantitative PCR), and for the dataset collected during spring, infections were also evaluated via IFAT (Indirect Fluorescent Antibody Test).
• Out of the tested horses, 64.8% were found to be carrying Theileria equi. The findings obtained from the molecular and serological tests were found to have a positive correlation and an agreement rate of nearly 80% with the parasitic load.
• The study also identified a connection between infection, pale mucus membranes, lower packed cell volume, and higher total solids, although these factors had minor clinical importance.
• While the parasitic loads in qPCR-positive samples were generally low, younger horses exhibited higher loads, hinting at a possible development of immunity towards the parasite.

Correlation between Infection Load and Exposure Patterns

• The research found that the rate of infection and parasitic loads were influenced by the housing management and tick exposure patterns of the horses.
• Prevalence was highest in horses exposed to constant tick redound in pasture farms, suggesting a state of endemic stability. Here, parasites were associated with T. equi 18S rRNA genotype D, low parasitemia, and high antibody titers.
• In contrast, horses kept in paddocks and exposed to ticks intermittently showed a pattern of endemic instability, with high parasitic loads during periods of tick presence.
• Stabled horses, with no tick exposure, presented a steady state with lower prevalence. Their infections were associated with a different genotype, A, along with low parasitemia and low antibody titers.

Conclusion and Suggestions

• Through the study, it was posited that identifying different risk groups could help in optimizing suitable treatment methods and control practices within endemic areas.
• This approach could ultimately assist in lowering the risk of clinical disease caused by the-parasite.