Viability and genetic diversity of Toxoplasma gondii in retail pork from a Brazilian region known for waterborne toxoplasmosis.

Toxoplasmosis is a major public health concern in Brazil due to its high prevalence and associated clinical burden. The northern region of Rio de Janeiro State is particularly notable for elevated human seroprevalence and strong evidence of waterborne transmission as a major route of infection. In parallel, farm animals in this region also exhibit high levels of exposure, together with marked genetic diversity of circulating Toxoplasma gondii strains. This study investigated the presence of T. gondii in retail pork from a highly endemic municipality, its potential to expose humans through the consumption of viable parasites, and the genetic diversity of isolates. A total of 100 pork samples (500 g each) were obtained from mapped butcher shops and subjected to mouse bioassay, resulting in the isolation of three viable strains. Multilocus sequence typing (MLST) identified three distinct genotypes, and in silico PCR-RFLP classified isolate TgPgBr17 within a genotype previously reported in chickens, supporting circulation across host species. In addition, nested PCR targeting the single-copy P43 gene detected T. gondii DNA in 31.3% (10/32) of a subset of retail pork samples, indicating that exposure along the pork supply chain may be more frequent than suggested by parasite isolation alone. Together, the detection of viable and genetically diverse T. gondii in retail pork highlights the epidemiological importance of farm animals as sources of human exposure in this endemic region.