morantel and Haemonchiasis

A strain of Haemonchus contortus from the Pietermaritzburg district of Natal was found to be resistant to levamisole (geometric mean efficacy 76.5%), morantel (41.9%), the benzimidazoles (oxfendazole: 33.7%) and rafoxanide (82.0%), but apparently fully susceptible to closantel and disophenol. In the case of ivermectin, a mean of 5.2% of the H. contortus was not removed at a dosage of 200 micrograms kg-1 live mass. A second strain of H. contortus, from Amsterdam in the south-eastern Transvaal, showed reduced susceptibility to levamisole (80.8%) and morantel (46.2%), the only 2 drugs tested. This is apparently the first report of resistance to the levamisole/morantel group of anthelmintics in sheep in South Africa.

Topics: Animals; Anthelmintics; Clinical Trials as Topic; Drug Resistance; Haemonchiasis; Haemonchus; Levamisole; Morantel; Pyrimidines; Sheep; Sheep Diseases; Trichostrongyloidea; Trichostrongyloidiasis

The gerbil Meriones unguiculatus, infected with three species of nematodes, each located in a separate part of the gastrointestinal tract, provided a reliable laboratory assay for the evaluation of broad-spectrum anthelmintic activity. Gerbils harbouring 6-day-old infections of Haemonchus contortus, Trichostrongylus colubriformis and T. sigmodontis were given selected broad-spectrum anthelmintics by gavage. Three benzimidazoles, thiabendazole, oxfendazole and albendazole, a tetrahydropyrimidine, morantel, an imidazothiazole, levamisole hydrochloride, a macrocyclic lactone, ivermectin and an experimental natural product, paraherquamide, were active against all three nematodes at various dosages. Trichostrongylus colubriformis was most sensitive to levamisole hydrochloride, morantel, thiabendazole and paraherquamide whereas ivermectin, oxfendazole and albendazole were more effective against H. contortus. All compounds were active against the caecal nematode T. sigmodontis although it was less sensitive than T. colubriformis. Haemonchus contortus was more sensitive than T. sigmodontis to all anthelmintics tested except thiabendazole.

Topics: Albendazole; Animals; Anthelmintics; Benzimidazoles; Female; Gerbillinae; Haemonchiasis; Haemonchus; Indolizines; Ivermectin; Levamisole; Male; Morantel; Parasitic Sensitivity Tests; Spiro Compounds; Thiabendazole; Trichostrongyloidea; Trichostrongyloidiasis; Trichostrongylus

Topics: Animals; Antinematodal Agents; Cattle; Cattle Diseases; Drug Resistance; Female; Fenbendazole; Haemonchiasis; Haemonchus; Male; Morantel; Parasite Egg Count

Benzimidazole resistant strains of Haemonchus contortus and Ostertagia spp were subjected to selection pressure over five laboratory generations with the recommended dose rates of either cambendazole, oxfendazole or morantel. A change in response, with larger residual worm burdens remaining after treatment at the fifth generation, was shown for both cambendazole and oxfendazole against both species of nematode. No change in response against either species are shown for morantel. The results are discussed in terms of the problem associated with inefficient removal of the adult parasites after treatment.

Topics: Animals; Anthelmintics; Benzimidazoles; Cambendazole; Carbamates; Drug Resistance; Haemonchiasis; Male; Morantel; Ostertagiasis; Selection, Genetic; Sheep; Sheep Diseases; Trichostrongyloidiasis

The anthelmintic efficacy of low-dose phenothiazine therapy, administered as a 1:40 phenothiazine: molasses mixture, was tested against patent infections of strains of Haemonchus contortus, Trichostrongylus colubriformis and Ostertagia spp susceptible or resistant to thiabendazole (an other benzimidazoles), levamisole and morantel tartrate. Phenothiazine reduced faecal egg output for both susceptible and resistant strains of all three nematodes. In daily doses of 0.25 g per sheep per day and above it completely inhibited larval production in susceptible strains. Against resistant strains, there was a reduced efficiency with 82.3 per cent inhibition of egg hatch at the 0.25 g per sheep per day level. Phenothiazine treatment had no significant effect on worm numbers for either susceptible or resistant worms. It is suggested that benzimidazole-resistant strains may be cross-resistant to phenothiazine.

Topics: Animals; Drug Resistance; Haemonchiasis; Levamisole; Male; Morantel; Ostertagiasis; Phenothiazines; Sheep; Sheep Diseases; Thiabendazole; Trichostrongyloidea; Trichostrongyloidiasis; Trichostrongylosis

Low-dose daily phenothiazine therapy, administered as a 1:40 phenothiazine:molasses mixture, was tested against sequential infections of strains of Haemonchus contortus. Trichostrongylus colubriformis and Ostertagia spp susceptible or resistant to thiabendazole, levamisole and morantel tartrate. Phenothiazine at a dose rate of 0.5 g per sheep per day significantly reduced the numbers of worm eggs per gram of faeces in both susceptible and resistant strains by an average of 48 per cent and 60 per cent respectively. Phenothiazine completely inhibited larval production in susceptible strains. With resistant worms, larval production was depressed by up to 85.7 per cent. Treatment with phenothiazine : molasses mixture reduced the numbers of worms which became established in resistant Ostertagia spp and susceptible T colubriformis but had no effect on the establishment of susceptible H contortus and Ostertagia spp or resistant H contortus and T colubriformis.

Topics: Administration, Oral; Animals; Drug Resistance; Haemonchiasis; Levamisole; Male; Morantel; Ostertagiasis; Phenothiazines; Sheep; Sheep Diseases; Thiabendazole; Trichostrongyloidea; Trichostrongyloidiasis; Trichostrongylosis

Following the apparent failure of levamisole to control infections of Haemonchus contortus in sheep at Lawes in south eastern Queensland, a strain of this parasite was isolated at the Animal Research Institute, Yeerongpilly. This strain was used to infect sheep at Yeerongpilly and the Merrindale Research Station, Victoria where four experiments to classify the resistance pattern of the parasite were carried out. Resistance to thiabendazole was first suspected in 1969, and these experiments confirmed that resistance to this drug was still present. They also showed that a strong degree of resistance had been developed to both levamisole and morantel tartrate. Other benzimidazole anthelmintics and also the organophosphorus compound naphthalophos were only moderately effective against the original isolate but rafoxanide, nitroxynil and phenothiazine were almost 100% effective. Other highly effective chemicals were disophenol and closantel. After passaging the strain for four generations with both levamisole and albendazole, resistance to both naphthalophos and the newer benzimidazole anthelmintics increased dramatically. This is the first report of a field strain of H. contortus exhibiting resistance to benzimidazole, non-benzimidazole and organophosphorus anthelmintics.

Topics: Albendazole; Animals; Anthelmintics; Australia; Benzimidazoles; Drug Resistance; Feces; Haemonchiasis; Haemonchus; Levamisole; Morantel; Rafoxanide; Sheep; Sheep Diseases; Trichostrongyloidea; Trichostrongyloidiasis

Topics: Animals; Drug Resistance; Haemonchiasis; Haemonchus; Levamisole; Male; Morantel; Pyrimidines; Sheep; Sheep Diseases; Thiabendazole; Trichostrongyloidea

The anthelmintic efficacy of morantel tartrate at 5mg/kg bodymass was investigated in three separate controlled trials comprising 68 calves. High anthelmintic activity was established against adult Haemonchus placei, Ostertagia ostertagi, Cooperia spp. (C.pertinata and C. punctata), Bunostomum phlebotomum and Oesophagostomum radiatum.

Topics: Animals; Cattle; Cattle Diseases; Haemonchiasis; Hookworm Infections; Morantel; Nematode Infections; Oesophagostomiasis; Ostertagiasis; Pyrimidines