Abstract: Objective   To explore the effect of X-ray irradiation on Echinococcus multilocularis protoscoleces in vitro.  Methods   Echinococcus multilocularis protoscoleces were collected from cysts of infected Meriones meridianus and then cultured in RPMI 1640 medium. Protoscoleces were subpackaged into culture flasks at a density of about 104 per flask after culture for 3 days. Each group has 10 culture flasks. There were seven groups named as blank control group, low dose group （15 Gy and 30 Gy）, medium dose group （45 Gy and 60 Gy）, high dose group（75 Gy and 90 Gy）, albendazole group （2 500 ng/ml）, 45 Gy X-ray+2 500 ng/ml albendazole group, and 75 Gy X-ray +2 500 ng/ml albendazole group. Protoscoleces received three radiations on every other day with a source-skin distance of 100 cm and at a dose rate of 200 cGy/min after 3 days in culture. At each day after irradiation, protoscoleces were counted by light microscope with 0.1% eosin staining, and calculated mortality rate （per 100 protoscoleces） until all the parasites in experimental groups died. At the same time, the morphological changes of protoscoleces were observed.  Results   There were significant differences in protoscolex mortality between X-ray groups and blank control group（P＜0.05）， between X-ray+albendazole groups and albendazole group（P＜0.05）. Protoscolex mortality in albendazole group were higher than that of blank control group（P＜0.05）. Significant difference were also found in protoscolex mortality between albendazole combined with radiation and radiation only（P＜0.05）. Before radiation, protoscoleces was normal with complete structure. After radiation, the parasites were mostly valgus type protoscoleces with disordered rostellar hooks and deformed acetabulum， and finally died.  Conclusion   X-ray can kill Echinococcus multilocularis protoscoleces in vitro.

Key words: Echinococcus multilocularis, Protoscolex, X ray, Albendazole, In vitro