Toxoplasma gondii Seroprevalence in Horses from Ukraine: an Investigation Using Two Serological Methods

Horses are recognized as important hosts for the zoonotic parasite Toxoplasma gondii, mainly because meat of infected horses can be a source of human T. gondii infections. However, the baseline knowledge on equine T. gondii infections is limited and lacking from many countries. This seroepidemiological study was set in Ukraine, a country where little is known about T. gondii prevalence in any host species.

We investigated 78 serum samples from horses, collected from Kyiv and Lviv regions of Ukraine, using a commercial enzyme-linked immunosorbent assay (ELISA) and a commercial modified direct agglutination test (DAT). The ELISA is intended to detect the presence of total antibodies against T. gondii, and the DAT detects specific anti-T. gondii immunoglobulin G antibodies. The cutoff titer for DAT seropositivity was a titer of 40.

Two horses were omitted from statistical analyses due to disagreeing ELISA results. Altogether 16 of the remaining 76 horses were seropositive with the ELISA, yielding an apparent seroprevalence estimate of 21.1% (95% confidence interval 13.0-31.3). Five horses tested positive with both ELISA and DAT, 11 horses tested positive with ELISA only, and one with DAT only. For 64 of the 76 horses, the results of ELISA and DAT agreed; the percent agreement was 84.2 and the Kappa statistic was - 1.5208, indicating poor agreement.

Our results add to the knowledge on the global epidemiology of T. gondii and exposure level of horses to the major zoonotic parasite, as well as to the discussion of challenges of applying serology to estimate exposure to T. gondii in horses.