Molecular Diagnosis and Quantification of Bovine Abortion Caused by Toxoplasma gondii in the Tropical Climate of Brazil.

Toxoplasma gondii is an obligate intracellular parasite, considered a zoonotic agent, and one of the main causes of foodborne diseases in humans. It is also responsible for infectious abortion and congenital defects in ruminants and human fetuses. While abortion in small ruminants due to T. gondii is well documented in the literature, bovine abortion is rare. In this article, we investigate the occurrence of T. gondii-induced abortion in cattle, providing molecular and immunohistochemical evidence from Brazilian herds. A total of 156 bovine fetuses were submitted for necropsy, and tissue samples were collected. Histopathology, immunohistochemistry, and real-time quantitative polymerase chain reaction (qPCR) were performed on these samples. Differential diagnosis was conducted for five bovine abortion diseases. Three samples (1.9%) showed lesions compatible with T. gondii on histopathology and tested positive by qPCR, with quantities of 476 copies/mg, 148 copies/mg, and 16 copies/mg, respectively. One positive sample was purified and prepared for sequencing, confirming identification as T. gondii. This study demonstrates that circulating T. gondii in Brazil is capable of causing abortion in cattle, highlighting the need for specific prophylactic measures against the pathogen and the importance of avoiding management practices that favor its establishment.