The prevalence of Toxoplasma gondii in sheep carcasses with special reference to its sustainable control using mice bioassay

The study was conducted to estimate Toxoplasma gondii cyst prevalence in three hundred slaughtered sheep carcasses slaughtered in Benha city, Qalubiya governorate abattoirs. Sample types were divided depending on the rearing system of sheep to random grazing and closed rearing system. Tissue samples were collected from muscles of heart, diaphragm and tongue of the examined sheep carcass. Results revealed that T. gondii was detected in higher prevalence in the samples collected from sheep of random grazing rearing system (39/150: 26.0%), than those of closed system rearing (23/150: 15.3%). Heart muscle revealed the highest prevalence of T. gondii (13.7%), followed by diaphragm (5.0%) and tongue (2.0%) samples, respectively. Moreover, the effect of different thermal treatments on T. gondii cyst were assessed by feeding experimental free mice on Toxoplasma infected tissues which were previously exposed to chilling, boiling or microwave cooking. It was proved that boiling and freezing had the potential to inactivate the infectivity of Toxoplasma cyst depending on the temperature degree and time of treatment; while, chilling, and microwave cooking treatments could not affect the infectivity of the cyst. Referring to the recorded results, and in dependence to expected hypothesis of statistical analyses, T. gondii was detected in a relatively higher prevalence than the expected prevalence for random grazing examined carcasses, while in lower prevalence in closed system reared carcasses. On the other hand, thermal treatments appeared to be effective in inactivating the infective cyst make the possible infected meat safe for human consumption.