Investigation of Toxoplasma gondii and Neospora caninum in different tissues of aborted foetuses of sheep in Van Province, Türkiye: Analysis by nested PCR, histopathological and immunohistochemical methods

Toxoplasma gondii and Neospora caninum are protozoon parasites from the intracellular apicomplexan family. Toxoplasma gondii is the cause of health and economic problems in the sheep industry worldwide. Neospora caninum is usually reported in cows and leads to infections causing abortions; however, its prevalence in sheep is not clear. The present study aimed to investigate the prevalence and pathology of T. gondii and N. caninum by PCR, histopathological and immune-histochemical methods in aborted sheep foetuses collected at different sheep flocks in the Van Province, Türkiye, in 2021. Firstly, the DNA of T. gondii and N. caninum were investigated by PCR in the brain, heart, and peritoneal fluid samples from 42 sheep foetuses. Toxoplasma gondii DNA was proved in 35.7% (15/42) of foetuses whereas N. caninum DNA was not determined in any of the samples. Histopathologically, all T. gondii positive brain tissue samples showed lymphohistiocytic multifocal encephalomyelitis and additional findings included necrotizing myocarditis in the positive heart samples. Toxoplasma gondii tachyzoites were identified in the lesions (diffuse or focal mononuclear cell infiltration in the meninges, and microglia proliferation, myocarditis with oedema) by anti-T. gondii antibodies by the immunohistochemical method. Based on our results, we can conclude that T. gondii is an important agent in sheep abortions and the PCR method is a suitable method for diagnosis which can also be used in heart tissue in pathological studies.