Molecular detection of Toxoplasma gondii in an aborted equine fetus and serological evidence of infection in mares enrolled in embryo transfer programs in Brazil.

Toxoplasma gondii infection is widely recognized as an important cause of reproductive losses in goats and sheep. However, the impact of this parasitic infection in mares remains poorly investigated, reflecting the neglect of this pathogen in equine production. The present study aimed to conduct a serological survey in 100 mares from farms enrolled in embryo transfer (ET) programs in Northeastern Brazil, report the first molecular detection of T. gondii in the placenta and aborted fetus of a mare in the country, and evaluate potential risk factors associated with infection. Anti-T. gondii IgG antibodies were detected using the indirect fluorescent antibody assay (IFA) with a cutoff of 1:64, followed by serial titration. Placentas and fetal organs from three mares from a farm with an abortion outbreak were also analyzed by PCR targeting the 18S rRNA gene of the family Sarcocystidae and the 529-bp repetitive element of T. gondii. A total of 31% of mares were seropositive (95% CI: 22.3-40.9), and both the fetus and placenta from one mare tested positive for the 18S rRNA gene and the 529-bp RE. The presence of cats on the farms and a history of abortion were identified as factors associated with seropositivity. These findings provide novel evidence contributing to the understanding of T. gondii infection in equine production systems.