Gerber, H.M.Alves, Regina M.R.Verwoerd, Daniel Wynand2014-09-012014-09-0120131990Van Wyk, JA, Bath, GF, Gerber, HM & Alves, RMR 1990, 'A field strain of Trichostrongylus colubriformis resistant to levamisole and morantel in South Africa ’, Onderstepoort Journal of Veterinary Research, vol. 57, no. 2, pp. 119-122.0330-2465http://hdl.handle.net/2263/41851The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.A strain of Trichostrongylus colubriformis from Nottingham Road, in Natal, was found to be solidly resistant to levamisole and morantel at the recommended dose levels. Untreated control sheep in fact harboured fewer worms at slaughter than either of the 2 treated groups. In contrast, the benzimidazoles and ivermectin were more than 99,9% effective against this worm strain. The possible implications of escalating resistance to anthelmintics in the gastrointestinal nematodes of sheep are discussed.en©South Africa. Dept. of Agricultural Technical Services. ©University of Pretoria. Dept. of Library Services (digital).Veterinary medicineVeterinary medicine -- South AfricaArticle