Detection of viable Toxoplasma gondii in retail venison

Toxoplasma gondii is an important zoonotic pathogen and the consumption of undercooked meat is known to be a significant risk factor for infection. Previously, a small-scale study of retail meat in Scotland identified a high incidence of T. gondii in venison products but the risk to public health could not be assessed as parasite viability was not determined. The aim of the present study, therefore, was to build on this work and establish T. gondii viability in retail venison. Twenty-three venison products were purchased from farm shops or supermarkets, and 50 g samples were processed for DNA extraction and qPCR. Any samples positive for T. gondii by qPCR were assessed for viability in a mouse bioassay. Viable T. gondii was isolated from 2 out of 5 (40 %) positive venison samples. Genotyping by RFLP and microsatellite analysis revealed both isolates to be Type II. This is the first study to report the presence of viable T. gondii in retail venison and highlights the potential risk to public health if this meat is eaten undercooked. Consumers should freeze venison, or cook it thoroughly, before consumption to reduce the risk of foodborne toxoplasmosis.