Abstract: Objective To observe the efficacy of tribendimidine and albendazole against Trichinella spirails in mice. Methods A total of 85 Kunming strain mice, infected orally with 100 T. spiralis larvae, was divided into 3 groups: group A （adult stage, 7 d after infection）, group B （migrating larva stage, 15 d after infection）, and group C （encapsulated larva stage, 35 d after infection）. Group A （35 mice） was equally divided into 7 sub-groups, tribendimidine and albendazole were each orally administered to 3 sub-groups both with doses of 6.25, 12.5, and 25 mg/kg respectively, the untreated sub-group served as control. Groups B and C （25 mice each） were both divided equally into 5 sub-groups. Mice in 2 sub-groups were treated respectively with the 2 drugs in a dose of 100 or 200 mg/kg, the untreated sub-group served as control. Mice in group A were sacrificed 2 d post-treatment and adult worms recovered from the small intestine were counted. Those in groups B and C were sacrificed 15 d post-treatment and intact diaphragm was then removed from each mouse. The muscle of diaphragm was digested by digestive solution and the larvae were counted by steromicroscope. Mean worm burden and mean worm reduction of each treated group were calculated and statistically compared with the control. Results The mean worm burden in sub-groups of group A treated with tribendimidine was significantly lower than that of the control （P<0.01） with a mean worm reduction of 63.3%, 86.2%, and 98.5%, respectively. In the same batch of mice treated with albendazole at a single dose of 6.25 and 12.5 mg/kg resulted in similar mean worm burden compared to the control （P<0.05）. While in the sub-group received albendazole at a higher dose of 25 mg/kg, the mean worm burden was significantly lower than that of the control （P<0.05）, with a mean worm reduction of 41.2%. The mean worm burden in group B was significantly lower than that of the control （P<0.01）. The mean worm reduction in the 2 sub-groups treated with tribendimidine or albendazole was 64.4% and 89.6%, or 56.7% and 78.4%, respectively. In group C, sig-nificantly lower mean worm burden was only found in the subgroup treated with albendazole at a higher dose of 200 mg/kg than the control （P<0.01） with a mean worm reduction of 71.8%. No effect was seen in the other 3 groups. Conclusion Tribendimidine exhibits potential effect against adult and migrating larva stage of T. spiralis in mice, but lacks effect against encapsulated larva stage of the parasite. Albendazole administered at a larger or multiple doses to mice endorses effect against its adult, migrating larva and encapsulated larva stages.

Key words: Tribendimidine, Albendazole, Trichinella spirails, Adult stage, Migrating larva, Encapsulated larva, Efficacy