Equine piroplasmosis status in the UK: an assessment of laboratory diagnostic submissions and techniques.
Authors: Coultous Robert M, Phipps Paul, Dalley Charlie, Lewis Jane, Hammond Toni-Ann, Shiels Brian R, Weir William, Sutton David G M
Journal: The Veterinary record
Summary
# Equine Piroplasmosis Status in the UK: Editorial Summary Equine piroplasmosis (EP) has traditionally posed minimal risk to UK horses due to the absence of competent tick vectors, yet recent reports of vector species establishment in British tick populations demand reassessment of disease risk. Between February and December 2016, researchers analysed 1,242 equine samples submitted for EP screening to two major UK diagnostic laboratories, employing both serological testing and PCR to detect evidence of current or previous infection; notably, 81.5 per cent of submissions were for export purposes rather than import screening. Serology revealed an 8.0 per cent prevalence of anti-EP antibodies, whilst PCR detected parasite DNA in only 0.8 per cent of samples—however, subsequent validation work suggested PCR sensitivity may be substantially compromised in archived material, indicating true carrier prevalence could be considerably underestimated. The findings expose a critical biosecurity gap: current UK movement regulations do not mandate EP screening on importation, yet carrier animals are being exported and the true burden of latent infection among the domestic population remains largely unquantified. For equine professionals, this work underscores the importance of screening before export, awareness of emerging tick vector distribution, and advocacy for enhanced importation protocols to prevent endemic establishment of a disease that, once established, would be difficult to eradicate.
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Practical Takeaways
- •Carrier horses pose an underestimated biosecurity risk to the UK horse population; practitioners should be alert to clinical signs and request appropriate testing for horses with compatible symptoms or recent import history
- •Current EP screening requirements are inadequate for importation purposes—clinicians should consider recommending EP testing for imported horses and those in contact with recently imported animals as a precautionary measure
- •PCR testing may underestimate true infection prevalence compared to serology; practitioners should interpret negative PCR results cautiously and consider serological testing as a complementary diagnostic approach
Key Findings
- •Serological prevalence of equine piroplasmosis was 8.0% among 1242 UK equine samples submitted for screening between February and December 2016
- •Parasite DNA was detected in only 0.8% of samples by PCR, though sensitivity analysis suggests actual proportion of PCR-positive animals is likely considerably higher
- •81.5% of submissions were for UK export testing while less than 0.1% were for importation purposes
- •Increased detection of EP tick vector species in the UK combined with relaxed movement regulations creates elevated risk of disease incursion and establishment