Comparative efficacies of closantel, ivermectin, oxfendazole, thiophanate and levamisole against thiabendazole resistant Haemonchus contortus in sheep.
Forty-nine sheep artificially exposed to a thiabendazole (TBZ) resistant isolate of Haemonchus contortus were assigned to 7 groups of 7 animals each and used to conduct a controlled anthelmintic trial. One group of sheep served as untreated infected controls and 6 groups were treated as follows: closantel, 5.0 mg kg-1; ivermectin, 0.2 mg kg-1; oxfendazole, 5.0 mg kg-1; thiophanate, 50 mg kg-1, levamisole, 7.5 mgkg-1 and thiabendazole, 66 mg kg-1. Eggs per gram of faeces were determined on days 21, 24 and day 34 (10 days post-treatment) after infection and all animals were necropsied for residual worm counts. The calculated efficacies of the treatments against H. contortus as indicated by worm reduction were closantel (100%), ivermectin (99.3%), oxfendazole (35.2%), thiophanate (56.7%), levamisole (98.6%) and thiabendazole (24.3%). The data therefore indicate that the TBZ-resistant isolate of H. contortus used was highly resistant to the 2 benzimidazole (BZ) anthelmintics, oxfendazole and thiophanate. This is the first report in Kenya of a field strain of H. contortus resistant to thiophanate.
Department of Veterinary Pathology and Microbiology, Faculty of Veterinary Medicine, Kabete, Nairobi, Denmark.
R M
RM
Waruiru
E H
EH
Weda
R O
RO
Otieno
J W
JW
Ngotho
H O
HO
Bøgh
D000818:Animals; D000871:Anthelmintics / Q000627:therapeutic use*; D001562:Benzimidazoles / Q000627:therapeutic use*; D004351:Drug Resistance; D005243:Feces / Q000469:parasitology; D005260:Female; D006188:Haemonchiasis / Q000188:drug therapy / Q000662:veterinary*; D007559:Ivermectin / Q000627:therapeutic use*; D007978:Levamisole / Q000627:therapeutic use*; D008297:Male; D010270:Parasite Egg Count; D012458:Salicylanilides / Q000627:therapeutic use*; D012756:Sheep; D012757:Sheep Diseases; D013827:Thiabendazole / Q000627:therapeutic use*; D013875:Thiophanate / Q000627:therapeutic use*
D000871:Anthelmintics; D001562:Benzimidazoles; D012458:Salicylanilides; D007978:Levamisole; D013875:Thiophanate; D007559:Ivermectin; C023342:closantel; D013827:Thiabendazole; C011030:oxfendazole