[Infectivity of the sparganum treated by praziquantel, gamma-irradiation and mechanical cutting].

An experimental study was performed to observe the infectivity of sparganum (plerocercoid of Spirometra erinacei) treated by praziquantel, gamma-irradiation and mechanical cutting. The spargana were obtained from the naturally infected European grass snake, Rhabdophis tigrina, or from the experimentally infected mice. A total of 83 mice (ICR strain) were divided into 3 experimental groups by the source of the damage, fed each with 5 spargana, and sacrificed 1 month later for worm recovery. In the praziquantel group, the worms were incubated in the concentration of 10 micrograms/ml (control: Tyrode for 4 hours) for 0.5, 1, 2 and 4 hours at 36 degrees C, and fed to mice. The recovery rate from mice in praziquantel group was not different from that (80%) of control group and in the range of 76-100%. In the gamma-irradiation group, the worms were irradiated by 10-1000 Gy with Cs137. The average recovery rates of 69-100% were not different from that of control up to 100 Gy. The rate was 56% under 150 Gy, and 5% by 1000 Gy. In the mechanical cutting group, the worms were cut at 0.5, 1, 2 and 3 mm from the anterior end of the scolex. The average recovery rates in each group were 70-90% and that of control was 90%. The present finding suggests that the sparganum be highly resistant to praziquantel, gamma-irradiation and mechanical cutting. The vitality center of the sparganum must be at the anterior end of its scolex.