Seromolecular and histopathological study on Toxoplasma gondii infection in ruminants in Aswan, Egypt.

Abstract

BACKGROUND: Toxoplasma gondii is a globally distributed zoonotic parasite that affects both humans and animals, with significant implications for public health and livestock production. The current research aims to update the information on the present prevalence of T. gondii and the risk factors associated with the infection in domestic ruminants in Aswan, Egypt, from August 2024 to January 2025, using serological, histopathological, and molecular approaches. METHODS: The blood of 387 domestic ruminants collected during the antemortem examination from four central abattoirs in the Aswan governorate, Upper Egypt, was inspected for the occurrence of anti-T. gondii antibodies through a modified agglutination technique. Data were confirmed by a nested polymerase chain reaction that targeted T. gondii DNA (B1 gene). Tissue specimens (heart and diaphragm) from seropositive animals were collected during postmortem examination and subjected to a histopathological and immunohistochemical approach. RESULTS: The overall occurrence of T. gondii was 29.5% (114/387), with seropositivity of 33.5% (52/155), 28.2% (22/78), 23.6% (21/89), and 29.2% (19/65) in cattle, buffalo, sheep, and goats, respectively. The studied risk factors (age, gender, breed, body condition, and location) in this study were detected to be significantly related to the presence of T. gondii infection (p ˂ 0.05). Histopathological examination detected tissue cysts in 38 out of 114 cardiac muscles of seropositive animals and failed to detect any cysts in the diaphragm tissue, indicated by encased, circular to elongated, basophilic cysts with many bradyzoites entrenched in muscle fibers by H&E staining, while showing intense brown granule staining of lymphoblastic cells by immunohistochemistry assay. Nested PCR confirmed the presence of the B1 gene of T. gondii in blood samples of all seropositive animals (100%). CONCLUSIONS: The combined use of serology, PCR, and IHC demonstrates that T. gondii is present in slaughtered ruminants in Aswan and that viable tissue cysts are present in edible tissues. These findings highlight a potential risk of zoonotic transmission through the consumption of undercooked meat and emphasize the need for monitoring and control measures to reduce the burden of foodborne toxoplasmosis in Egypt.