Background Helminthiasis causes losses in livestock production and anthelminthics are used to treat helmintic infections. Resistance has necessitated the need for development of more effective alternatives. Plants offer a promising alternative and in Meru County plants have been traditionally used for treating helminthiasis, however there lacks scientific prove of their efficacy. Objective This study aims to investigated efficacy of Bridelia micrantha, Aframomum zambesiacum, Hagenia abyssinica, Rubus apetalus, Thespecia garckeana, Physalis peruviana and Caesalpina volkensii against Haemonchus contortus. Methods It entailed screening of methanolic extracts of these plants against Haemonchus contortus, from sheep farms in Muguga Kenya. Their efficacy was tested in-vitro using eggs and larvae of Haemonchus contortus. Egg hatchability was determined after 48-hour incubation with extracts while larvae survival was determined after six days incubation. Physiological saline was the negative control while albendazole was the positive control. One way ANOVA was conducted followed by Tukey’s test. Results P. peruviana and R. apetalus, inhibition percentages of 95.24±0.54, 90.00±1.00, 88.24±0.66 and 96.55±0.45, 85.71±0.79, 82.14±0.76 at 50mg/ml, 25mg/ml and 12.5 mg/ml respectively was achieved with no significant difference (P<0.05) in egg hatchability with the positive control. The highest larvicidal mean percentage of 100.00±0.00 was achieved by R. apetalus and H. abyssinica across the three dosages with no significant difference between them and albendazole. GC-MS analysis revealed compounds such as terpenoids were conspicuously present which accounted for some of the activity. Conclusion This observation lenders support to the traditional use of the plant extracts for the treatment of suspected helminthic infections.

Keywords: Haemonchus contortus; anthelmintic; essential oil; monoterpenoids; terpenes.