Molecular Detection of Toxoplasma gondii and Neospora caninum in Naturally Infected Sheep, Cow, and Buffalo Milk

Abstract

Introduction: Toxoplasma gondii and Neospora caninum are apicomplexan protozoan parasites belonging to the family Sarcocystidae. Toxoplasma gondii is a significant zoonotic pathogen responsible for abortion and congenital infections in both humans and animals worldwide. Transmission to humans occurs through ingestion of tissue cysts (bradyzoites) in raw or undercooked meat, oocysts in felid faeces, transplacental transmission from infected mothers, or consumption of milk containing tachyzoites. Neospora caninum is a major cause of reproductive failure in cattle, manifesting as abortion, stillbirth, infertility, early foetal death, and decreased milk production. The parasite has been identified as a leading cause of bovine abortions, particularly in European dairy herds. Although N. caninum is not definitively proven to be zoonotic, its close phylogenetic and biological relationship with T. gondii raises concerns about potential human infection risk that warrant investigation. Materials and methods: This study investigated the presence of T. gondii and N. caninum DNA in milk samples from dairy animals in Samsun province, Turkey. Between September 2022 and June 2024, raw milk samples (10 ml) were collected from cattle (n = 107), sheep (n = 100), and buffaloes (n = 100) at various local dairies. DNA extraction and PCR amplification were performed using Tox4-Tox5 and Np6-Np21 primer pairs for T. gondii and N. caninum, respectively. Results: Toxoplasma gondii DNA was detected in 21% (21/100) of buffalo, 19% (19/100) of sheep, and 14.95% (16/107) of cattle milk samples. Neospora caninum DNA was found in 16% (16/100) of sheep, 13.8% (14/107) of cattle, and 12% (12/100) of buffalo milk samples. These findings indicate a substantial prevalence of both parasites in raw milk intended for human consumption in the region. Conclusion: Given the potential viability of tachyzoites in unpasteurised milk and dairy products, consumption of raw milk may represent a significant risk factor for human infection with T. gondii and possibly N. caninum. Further comprehensive and systematic studies are needed to better characterize the public health risks associated with these parasites in raw milk and dairy products. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2025.