Abstract
A survey to detect anthelmintic resistance in nematode parasites of sheep was conducted on 10 randomly-distributed farms in the Chivhu District, Mashonaland East Province, Zimbabwe. Before the survey, a questionnaire was circulated to the farmers concerning nematode parasite control. Results showed that parasite control using anthelmintic treatment was the only method practised and that the benzimidazoles were the most frequently used anthelmintic drugs. The faecal egg count reduction test was used to detect resistance. The anthelmintic groups tested were benzimidazoles, levamisole and ivermectin. Resistance to benzimidazoles was detected on 6 of 10 farms and levamisole resistance on 2 of 3 farms. Ivermectin resistance was not observed on the farms surveyed. Post-treatment larval cultures indicated that Haemonchus contortus survived administration of fenbendazole, albendazole, oxfendazole and levamisole. A Cooperia sp. strain resistant to albendazole was detected and this is the first report in Zimbabwe of a resistant parasite in this genus.
Highlights
Gastrointestinal nematodes of importance in sheep in southern Africa belong to the genera Haemonchus, Cooperia, Trichostrongylus a nd Oesophagostomum
MATERIALS AND METHODS The survey on anthelmintic resistance was conducted on commercial sheep farms in the Chivhu District of Mashonaland East Province situated in the highveld area of Zimbabwe
Resistance to anthelmintics was presumed present when % faecal egg count reduction (FECR) value is lower than 95 %
Summary
Gastrointestinal nematodes of importance in sheep in southern Africa belong to the genera Haemonchus, Cooperia, Trichostrongylus a nd Oesophagostomum. In Zimbabwe, Haemonchus contortus is by far the most predominant nematode in sheep[6]. The intensification of sheep production has led to an increasing reliance on anthelmintics for control of gastrointestinal parasites[2] and anthelmintic resistance has become an increasingly widespread problem in many countries[14]. It is a cause of concern for all those interested in controlling helminth parasites of sheep. Zimbabwe is no exception owing to the indiscriminate use of anthelmintics by aDepartment of Paraclinical Veterinary Studies, Faculty of Veterinary Science, University of Zimbabwe, Box MP 167, Mount Pleasant, Harare, Zimbabwe
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