Study of survival rate of Toxoplasma gondii tachyzoites during the Lighvan traditional cheese-making process with different concentrations in 24 hours

Toxoplasma gondii is the causative agent of Toxoplasmosis, an obligate intracellular parasite of warm-blooded animals. This study aimed to investigate the survival rate of T. gondii tachyzoites in the traditional Lighvan cheese-making process with different concentrations in 24 hours. For this purpose, the first 2 liters of fresh sheep milk were prepared from milk collection centers and transferred to the Laboratory. The 8×107 parasites of T. gondii strain RH and rennet were added to the milk. After stirring, make slices 2 in the cheese and separate containers containing different concentrations. NaCl containing 4, 8, 12, and 16% were placed in 24 hours with three repetitions. After the mentioned periods, each Lighvan cheese treated was completely homogenized with PBS for 5 minutes with 2000 rpm centrifugation. The resulting sediment was injected intraperitoneally with three repetitions to 3 rats. At the same time, some Lighvan cheese was fed orally to each of them. Survival rates of T. gondii tachyzoites were assessed by mouse mortality. The results showed that the survival rates of mice at concentrations of 12 and 16% for 24 hours were 100%. Also, at a concentration of 4% at 24 hours, the highest mortality rate of mice was observed, which indicates the survival of the parasite at this concentration and duration. This study showed that to inactivate possible T. gondii tachyzoites in contaminated milk used in the traditional Lighvan cheese industry, it is better to place the prepared cheese in 12% and 16% salt concentrations for more than 24 hours.