Serological and molecular detection of Babesia caballi and Theileria equi in Mexico: A prospective study.
Authors: Salinas-Estrella Elizabeth, Ueti Massaro W, Lobanov Vladislav A, Castillo-Payró Evelio, Lizcano-Mata Amelia, Badilla César, Martínez-Ibáñez Francisco, Mosqueda Juan
Journal: PloS one
Summary
# Editorial Summary: Equine Piroplasmosis in Mexico Equine piroplasmosis, caused by the blood parasites *Babesia caballi* and *Theileria equi* and transmitted by ticks in tropical and subtropical regions, presents diagnostic challenges due to non-specific clinical signs; this prospective study addressed a significant knowledge gap regarding the prevalence of these pathogens in Mexico, where environmental conditions favour tick survival and pathogen persistence. Researchers collected matched serum and whole blood samples from 269 horses across 24 tick-endemic locations in tropical and subtropical Mexico, employing ELISA serology, nested PCR (nPCR), duplex quantitative PCR (qPCR), and DNA sequencing to characterise infection patterns. Serological testing revealed substantial exposure rates (55.7% for *B. caballi* and 68.4% for *T. equi*), whilst molecular detection demonstrated active infections: nPCR identified 7.8% *B. caballi* and 78.8% *T. equi* positivity, with duplex qPCR findings of 15.24% and 59.11% respectively, with sequencing confirming both pathogens' presence. The marked discrepancy between serological and molecular findings suggests either carrier animals with waning parasitaemia or chronic infections with strong antibody responses, highlighting the importance of using both diagnostic approaches; the high prevalence of *T. equi* particularly warrants attention from practitioners in affected regions. For farriers, veterinarians, and other equine professionals working in Mexico's endemic areas, these findings underscore the need for heightened awareness of piroplasmosis risk, appropriate tick control strategies, and consideration of serological screening protocols for horses, especially those involved in international movement.
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Practical Takeaways
- •If you work with horses in Mexican tropical/subtropical regions, expect high exposure rates to both parasites; serological testing alone underestimates active infections compared to molecular methods
- •Theileria equi appears more prevalent and persistent than B. caballi in this region—PCR testing is more reliable than serology for detecting current infections
- •Tick control and vector management are critical in endemic areas; consider screening horses before movement to non-endemic regions
Key Findings
- •Seroprevalence of B. caballi was 55.7% and T. equi antibodies were 68.4% in Mexican horses tested by ELISA
- •qPCR detected 15.24% B. caballi and 59.11% T. equi positive samples, indicating active or recent infections
- •T. equi showed higher molecular prevalence (78.8% by nPCR) compared to B. caballi (7.8% by nPCR)
- •Both parasites are widespread in tropical and subtropical regions of Mexico with established tick populations