[Effect of gamma-irradiation on infectivity of Clonorchis sinensis metacercariae]

The purpose of the present study was to observe the survival and development of Clonorchis sinensis metacercariae in their final hosts after Co-60 gamma irradiation exerting on both metacercariae isolated or in fish. Guinea pigs or albino rats were orally infected by gavage. Bio-assay, fecal examination for ova and dissection of infected animals were used for the estimation of minimum effective dose of gamma irradiation to control infectivity of Clonorchis sinensis metacercariae. Results showed that the minimum effective irradiation dose for isolated metacercariae was 0.05 kGy. The LD50 of the irradiation dose for metacercariae in fish was 0.05 kGy, and the minimum effective dose was 0.15 kGy. No significant difference in radiation susceptibility to Co-60 gamma irradiation was found among Clonorchis sinensis metacercariae in fishes collected at different localities in the northern, middle or southern parts of China. The present finding suggests that irradiation of the fish at a dose of 0.15 kGy could control the infectivity of Clonorchis sinensis metacercariae and thus be adopted as a control measure in preventive medicine.