Anthelmintic efficacy of Nauclea latifolia extract against gastrointestinal nematodes of sheep: in vitro and in vivo studies.

Direct effects of Nauclea latifolia extracts on different gastrointestinal nematodes of sheep is described. In vivo and in vitro studies were conducted to determine possible anthelmintic effect of leaf extracts of Nauclea latifolia toward different ovine gastro intestinal nematodes. A larval development assay was used to investigate in vitro, the effect of aqueous and ethanolic extracts of N. latifolia towards strongyles larvae. The development and survival of infective larvae (L(3)) was assessed and best-fit LC(50) values were computed by global model of non-linear regression analysis curve-fitting (95% CI). Twenty sheep harbouring naturally acquired gastrointestinal nematodes were treated with oral administration of ethanolic extracts at a dose rate of 125 mg/kg, 250 mg/kg and 500 mg/kg to evaluate therapeutic efficacy, in vivo.The presence of the extracts in the cultures decreased the survival of larvae. The LC(50) of aqueous and ethanolic extract were 0.704 and 0.650 mg/ml respectively and differ significantly (P<0.05, paired t test). Faecal egg counts (FEC) on day 12 after treatment showed that the extract is effective, relative to control (1-way ANOVA, Dunnett's multiple comparison test), at 500 mg/kg against Haemonchus spp, Trichostrongylus spp (p<0.05), Strongyloides spp (P < 0.01); at 250 mg/kg against Trichuris spp (P < 0.01) and ineffective against Oesophagostomum spp (p>0.05). The effect of doses is extremely significant; the day after treatment is sometimes significant while interaction between dose and day after treatment is insignificant (2-way ANOVA). N. latifolia extract could therefore find application in the control of helminth in livestock, by the ethnoveterinary medicine approach.