The impact of dry ageing vacuum-packed pork on the viability of Toxoplasma gondii tissue cysts

The present study evaluated the viability of Toxoplasma gondii tissue cysts in dry-aged pork loins (m. longissimus) after 14, 21 and 28 days under controlled temperature (0 °C ± 1 °C). The pigs (n = 9) were orally inoculated with 3,000 T. gondii oocysts. The right loin of each pig was aged for a predetermined period, and the left loin was kept unprocessed as a control. Two experiments were performed. In Experiment 1, the loins of three pigs were aged for 14 days and then bioassayed in both cats and mice. In Experiment 2, the loins of six pigs were bioassayed only in mice, and the ageing periods were 14, 21, and 28 days. Toxoplasma gondii tissue cysts remained viable in loins aged up to 14 days, as confirmed by bioassays in cats and mice. Viable T. gondii was not recovered by bioassays in mice from loins that were aged for 21 or 28 days. These results demonstrate that T. gondii remained viable in vacuum-packed dry-aged pork loins for 14 days at controlled temperature but not for 21 days or longer. •Toxoplasmosis is caused by the obligate intracellular protozoan Toxoplasma gondii.•Transmission modes are oocysts, congenitally or raw or undercooked meat with cysts.•Viability of T. gondii tissue cysts in vacuum-packed dry aged pork were evaluated.•Toxoplasma gondii remained viable for 14 days at 0 °C±1 °C but not at 21 days or longer.