thiophanate and Trichostrongyloidiasis

Following reports of suspected gastrointestinal strongylid nematode resistance to thiophanate in sheep and goats at Sokoine University of Agriculture (SUA), Tanzania, field strains of Haemonchus contortus, one from SUA and another from Kimamba, Tanzania, were selected for a critical controlled test to evaluate the efficacy of thiophanate. The SUA H. contortus strain in goats showed a marked resistance to thiophanate at an oral dose of 50 mg kg-1 liveweight (efficacy = 24.1%), while the Kimamba H. contortus strain showed very marked susceptibility (efficacy = 99.7%) to thiophanate at the same oral dose. This is the first report from East Africa of a field strain of H. contortus resistant to thiophanate. The incidence of resistant strains of strongyloid parasites to benzimidazole anthelmintics in sheep and goats in East Africa is on the increase. The magnitude of this problem should be evaluated and remedial solutions sought.

Topics: Abomasum; Animals; Carbamates; Drug Resistance; Feces; Female; Goat Diseases; Goats; Haemonchiasis; Haemonchus; Parasite Egg Count; Random Allocation; Tanzania; Thiophanate; Trichostrongyloidea; Trichostrongyloidiasis

The occurrence of a field strain of Haemonchus contortus which was resistant to thiophanate and susceptible to thiabendazole and levamisole is reported. The LD95 of thiophanate for the strain was found to be 156.1 mg/kg and its resistance factor was 6.7. In possessing specific thiophanate resistance it differed from previously reported thiophanate resistant strains of H contortus which have been benzimidazole resistant worms that have possessed cross resistance to thiophanate.

Topics: Animals; Carbamates; Drug Resistance; Feces; Haemonchiasis; Haemonchus; Levamisole; Male; Sheep; Sheep Diseases; Thiabendazole; Thiophanate; Trichostrongyloidea; Trichostrongyloidiasis

Topics: Animals; Carbamates; Cattle; Cattle Diseases; Haemonchiasis; Thiophanate; Trichostrongyloidiasis

Topics: Animals; Carbamates; Cattle; Cattle Diseases; Larva; Nematode Infections; Ostertagiasis; Thiophanate; Trichostrongyloidiasis

Thiophanate administered daily at low dosages reduced nematode faecal egg output, egg hatchability and parasitic worm burdens in treated lambs and ewes. Six daily doses of 1 or 3 mg per kg thiophanate (approximately 1/25th to 1/75th of the median therapeutic dose), given to lambs experimently infected with Trichostrongylus colubriformis, were partially effective in suppressing faecal egg output and egg hatchability. Six doses of 5 mg per kg per day were effective in lambs infected with Haemonchus contortus and Nematodirus spathiger. Daily doses of thiophanate (50 or 200 mg per head) given over 14 weeks to lambs grazing contaminated pasture resulted in improved productivity (the higher dosage) and suppression of output of viable eggs and reduced worm burdens (both dosages). Reduced output of viable eggs was also obtained in housed, lactating ewes receiving 5 or 7 mg per kg thiophanate dispersed daily in the feed for 11 or nine weeks respectively after lambing.

Topics: Animals; Antinematodal Agents; Carbamates; Haemonchiasis; Ostertagiasis; Sheep; Sheep Diseases; Thiophanate; Trichostrongyloidiasis

In a trial with natural infections of trichostrongyles in sheep, thiophanate and thiabendazole at 100 mg/kg and 200 mg/kg bodyweight were highly effective in removing all stages of development of the helminths including the inhibited stages. At 50 mg/kg bodyweight however, both drugs were only capable of reducing helminth load.

Topics: Animals; Carbamates; Sheep; Sheep Diseases; Thiabendazole; Thiophanate; Trichostrongyloidea; Trichostrongyloidiasis; Trichostrongylosis

Topics: Animals; Carbamates; Cattle; Cattle Diseases; Haemonchiasis; Nematode Infections; Ostertagiasis; Sheep; Sheep Diseases; Thiophanate; Trichostrongyloidiasis