Detection of Theileria equi and Babesia caballi infections in Venezuelan horses using Competitive-Inhibition ELISA and PCR.

The focus of this study was the detection of equine piroplasmosis in Distrito Capital, Miranda, Aragua, Guárico and Apure States from Venezuela, using two methods: Competitive-Inhibition ELISA and multiplex PCR and the analysis of the possible differences in occurrence in relation to the primary purpose of the horses, which is related to varied degrees of exposure to tick. Antibody levels to Babesia caballi and Theileria equi were assessed in 694 equine serum samples using Competitive-Inhibition ELISA, while PCR assays were performed in 136 horses, using two sets of oligonucleotides to establish the presence of T. equi, B. caballi or both. The overall seroprevalence of equine piroplasmosis was 50.2%, antibodies to B. caballi were found in 161 horses (23.2%), whereas 97 (14.0%) were seropositive to T. equi and 90 (13.0%) were positives to both parasites (mixed infections). PCR determinations (n=136) showed a prevalence of 66.2%, distributed in 84 (61.8% positives) for T. equi and, 6 (4.4%) were positive to both parasites. The cELISA showed higher levels of prevalence of B. caballi and mixed infections, as compared to the PCR method. This discrepancy can be explained by the different parameters that are evaluated by each technique, PCR detect the parasite itself, while cELISA detects antibodies to the parasite. By PCR, the highest prevalence was found in Apure state, where 92.3% of the samples were positive to T. equi infections. In this locality, free grazing animals are used for livestock management. This high prevalence may be linked to the tick species present in that area. More epidemiological studies will be necessary to assess the epidemiological status of equine piroplasmosis in Venezuela.