Field investigation of anthelmintic efficacy and risk factors for anthelmintic drug resistance in sheep at Bedelle District of Oromia Region, Ethiopia

Abstract

The study was conducted to investigate the status of anthelmintic (AH) efficacy and associated risk factors for AH resistance in sheep. Questionnaire surveys were undertaken to establish the AH utilization practices of sheep owners at the study area and identify risk factors. Four hundred fourteen sheep were sampled of which 180 sheep were selected based on their higher egg count for the fecal egg count reduction test (FECRT) to assess the efficacy of albendazole, tetramisole and ivermectin against gastrointestinal nematode parasites prevailing in sheep. Fecal culture and postmortem examination techniques were used to identify the species of nematode parasites prevalent before and after treatment. The results show that: 1) albendazole and tetramisole were the most frequently used AH in the area, 2) farmers get the drugs with or without prescription from various sources (10% open markets, 18% private drug stores and 72% government animal health clinics and 3) the prevalence of gastro-intestinal nematode infection in the study areas was 72%. 4) The FECRT revealed all the three tested AH were effective with egg count reduction levels of 96%, 99% and 97% respectively for albendazole, tetramisole and ivermectin. However, post-treatment fecal cultures and postmortem adult worm recovery showed that some Haemonchus contortus worms have escaped the treatments. In conclusion, no anthelmintic resistance was detected from clinical cure point of view but the population of H. contortus that has escaped the treatments deserves further scrutiny as this parasite is the most prolific and highly pathogenic in sheep.

Key words: Anthelmintic efficacy, FECRT, Gastrointestinal Nematodes, Risk Factors, Sheep.