Effect of domestic freezing on the viability of Toxoplasma gondii in raw and dry-cured ham from experimentally infected pigs

Abstract

Toxoplasma gondii is the causative agent of the parasitic disease toxoplasmosis, which is an important food borne zoonosis. Eating undercooked meat of infected animals has been considered the major transmission route of T. gondii to humans. The present study evaluates the efficacy of domestic freezing on the inactivation of T. gondii bradyzoites in raw and dry-cured ham. Meat (raw and dry-cured ham) of a pig experimentally orally inoculated with 4,000 oocysts of T. gondii VEG strain was subjected to domestic freezing of -20 ºC at different days. The effect was evaluated by bioassay in mice followed by qPCR. In raw ham and dry-cured ham, temperature of -20 ºC for 7 and 14 days respectively did not inactivate T. gondii . More studies are needed to find the right temperature and time needed to render the bradyzoites non-infectious for human. Meanwhile, the recommendations of freezing to inactivate T. gondii in raw or dry-cured meats must be revisited considered that it does not reduce the risk of infection.