Effect of Temperature and Salinity on Survival of Protoscoleces of Hydatid Cyst in Liver In Vitro.

Hydatid cyst is the metacestode stage of Echinococcus granulosus that occurs in herbivores and humans as intermediate hosts by consuming parasite eggs through forage and vegetables. Carnivores, as definitive hosts, become infected by consuming infected vesicles of herbivores. The most effective treatment for a hydatid cyst is surgical operation. Inactivating E. granulosus protoscoleces through heating, cooling, or chemicals such as sodium chloride can be considered an effective method for controlling hydatidosis in both humans and animals. The main objective of this study was to evaluate the effect of different temperatures and salinity conditions on the survival of Echinococcus granulosus protoscoleces. For this purpose, 50 g of infected liver (in triplicate) was separately treated with different temperatures (+10°C, +50°C, +60°C, +72°C, and -20°C) and concentrations of sodium chloride (5%, 10%, 15%, and 20%) for 3, 6, 12, 24, 48, and 72 h. Additionally, 50 g of infected liver was stored separately in the refrigerator (+4°C) as a control group. The survival rate of the protoscoleces was evaluated by staining with 1% eosin under a light microscope. The results showed that the protoscoleces were significantly affected, with 100% mortality at -20°C after 0.5 h, and complete death at +72°C, +60°C, +50°C, and +10°C after 1, 1.5, 3, and 24 h, respectively (p < 0.005). Similarly, the protoscoleces in the liver mass survived at 5% NaCl after 3 h but died at 10% after 24 h, at 15% after 12 h, and at 20% after 6 h. It is concluded that exposing the liver infected with protoscoleces hydatid cyst to a temperature of -20°C and a sodium chloride concentration of 10% for 24 h is suitable for inactivating the protoscoleces.