Efficacy and safety of artemether against a natural Fasciola hepatica infection in sheep.

Triclabendazole is the current drug of choice against Fasciola spp. infections in livestock, but resistance has become a major problem. In this study, we assessed the efficacy and safety of artemether, a derivative of artemisinin, in sheep with a low natural Fasciola hepatica infection. Artemether was administered orally or intramuscularly; sheep were monitored for 8 h posttreatment and then once daily for adverse events, and drug efficacy was estimated by fecal egg count reductions and worm burden reductions. Single 40- and 80-mg/kg oral doses of artemether showed no effect on F. hepatica egg and worm burden. Treatment with a single 160-mg/kg intramuscular dose of artemether significantly reduced the egg burden (64.9%) and worm burden (91.3%). At half this dose, a worm burden reduction of 65.3% was obtained, which was still statistically significant (P < 0.05). The lowest intramuscular dose of artemether investigated (40 mg/kg) yielded no effect on egg counts and worm burden. There were no adverse events due to artemether; however, two abortions were observed 7 days posttreatment. In conclusion, artemether shows interesting fasciocidal properties in sheep, but embryotoxicity is of concern. Further studies are warranted to assess the potential of additional artemisinin derivatives and other peroxidic compounds for the treatment of Fasciola spp. infections in different ruminants.