Molecular and Serological Detection of Vector-Borne Pathogens Responsible for Equine Piroplasmosis in Europe between 2008 and 2021

Abstract

Equine piroplasmosis (EP) is caused by Theileria (T.) equi and/or Babesia (B.) caballi. The aim was to assess the percentage of positive test results for EP in horses in Europe and to identify risk factors for pathogen contact/infection. This study included results from PCR and competitive enzyme-linked immunosorbent assay testing requested by European veterinarians between 2008 and 2021. Binary bivariate logistic regression was used to analyze risk factors. A total of 4060 horses were included. PCR testing was positive in 9.7% (154/1589), serology for T. equi in 15.2% (393/2591) and for B. caballi in 6.8% (175/2578). The odds of positive serology increased by 6.8% (B. caballi, p = 0.008) and 9.5% (T. equi, p < 0.001) each year. Regionality had a statistically significant impact on PCR (Eastern p = 0.047/OR = 1.605; Southern p = 0.029/OR = 1.451; Central p = 0.007/OR = 0.617) and serological testing for T. equi (Southern p < 0.001/OR = 2.521; Central p < 0.001/OR = 0.537; Northern p = 0.003/OR = 0.462), as well as breeds on seroprevalence of B. caballi (heavy horses: p = 0.016/OR = 2.239) and T. equi (ponies: p = 0.007/OR = 0.340; warmbloods: p = 0.025/OR = 1.602). In conclusion, there was a significant geographical impact on the results of PCR and serology, consistent with known vector habitats. The rising numbers of horses tested serologically positive highlights the importance of surveillance.

Germany-wide citizen science study reveals spread of Babesia canis-infected Dermacentor reticulatus ticks by dogs travelling within the country

“…Therefore, the risk of endemisation exists. Theileria equi is even more frequently detected in German horses ( Axt et al, 2024 ); however, the employed SYBR Green qPCR in the present study did not target Theileria spp., as the study was primarily designed as a survey for B. canis .…”

“…In contrast to the rising incidence of canine babesiosis, only few clinical cases of B. caballi infections have been reported in Germany so far ( Adam et al, 2017 ; Dirks et al, 2021 ; Vogt et al, 2024 ). However, data from a diagnostic laboratory show that horses are regularly tested B. caballi- positive by serology and sometimes by PCR in Germany ( Axt et al, 2024 ), presumably after travelling to or import from other countries, and might act as a source of infection for ticks. Therefore, the risk of endemisation exists.…”