Comprehensive evaluation of Toxoplasma gondii in sheep intended for human consumption in Brazil: seroprevalence, isolation, and genotyping.

Abstract

Ovine toxoplasmosis caused by Toxoplasma gondii is a zoonotic disease responsible for triggering reproductive problems in sheep with great public health impact. The zoonotic risk for humans occurs through the ingestion of meat contaminated with bradyzoites, water and vegetables contaminated with oocysts, or by ingesting unprocessed sheep milk contaminated with tachyzoites. The study aimed to determine the seroprevalence, isolate, and genetically characterize T. gondii from sheep in northeastern Brazil. Blood and tissue samples, including the liver, heart, brain, lung, and diaphragm, were collected from 256 sheep in slaughterhouses. The presence of anti-T. gondii IgG antibodies was assessed by the indirect fluorescent antibody test (IFAT), and sera with titers ≥ 1: 64 were considered positive. Tissue samples from seropositive sheep were digested in acidic pepsin solution and inoculated into two Swiss mice for T. gondii isolation and further characterized by molecular methods. The prevalence of anti-T. gondii antibodies in sheep was 31.64% and the isolation rate was 40.7%. Sixteen out of 33 isolates were submitted to mnRFLP-PCR using ten genetic markers. Four isolates were fully genotyped, and four isolates were amplified at least in one marker. All isolates were characterized as atypical genotypes, and ToxoDB #57 (n = 3) and #143 (n = 1) were identified. The detection of viable T. gondii in sheep from slaughterhouses in Brazil highlights the risk of human exposure. There is the need for proactive control and prevention measures to mitigate the risk of human exposure, considering the importance of sheep meat as a source of protein to humans.