Serological and molecular detection of Theileria equi infection in horses in Hungary

The prevalence of Theileria equi infection was studied in 324 healthy horses from 27 farms in Hungary with cELISA and IFAT and the blood samples of 101 horses selected randomly were also examined by PCR. The results indicate that there are many stud farms where one or more horses are infected with T. equi. Among 27 farms 17 (67.9%) were found to have seropositive horses. The seroprevalence of theileriosis among the tested stud farms ranged between 0 and 100%. No marked differences were found in seropositivity between geographical areas. The overall prevalence of positive samples was 32.0% with cELISA as well as with IFAT. The results obtained with cELISA and IFAT in this study had the strongest agreement, except for 9 samples in which the two serological tests gave different results. The prevalence of infection among 101 horses was 49% with PCR. All 14 sequenced samples were found by BLAST analysis to be closest to the T. equi 18S rRNA gene sequences in GenBank with a similarity of ≥ 99%. No significant association was found between the seropositivity and the age of horses. Horses below 5 years of age had three times higher chance to be PCR-positive, than older ones. There was no significant association between the gender and the results of diagnostic tests (cELISA: p=0.40; IFAT: p=0.25; PCR: p=0.41). Based on the findings, the prevalence of equine theileriosis is much higher than expected and it occurs in many regions of the country unlike equine babesiosis. To the authors' knowledge, this is the first report of the serological and molecular survey of T. equi infection in horses in Hungary.