Overberg research projects. XV. The efficacy of different anthelmintics against field strains of nematode parasites of sheep in the southern Cape Province.

Controlled anthelmintic tests and faecal egg count reduction tests were carried out on natural infections of nematode parasites in sheep on 4 farms in the southern Cape Province. Albendazole, fenbendazole, ivermectin, levamisole, morantel citrate and a combination of albendazole and closantel sodium were tested. Every farm harboured anthelmintic resistant nematode parasites. Adult as well as immature Teladorsagia spp. were resistant to albendazole and fenbendazole, immature Teladorsagia spp. to albendazole/closantel, adult and immature Nematodirus spp. to albendazole/closantel and adult Nematodirus spp. to fenbendazole.