The efficiency of various anthelmintics against field populations of Haemonchus contortus resistant to thiabendazole

Efficacy of Myrsine africana, Albizia anthelmintica and Hilderbrantia sepalosa herbal remedies against mixed natural sheep helminthosis in Samburu district, Kenya

Traditional livestock healers from Samburu and Turkana communities in Samburu District of Kenya were identified and recruited for participation in this study. Sheep with mixed gastrointestinal helminthosis were purchased from nomadic livestock owners in the area. Three herbal anthelmintic remedies, viz. Myrsine africana, Albizia anthelmintica and Hilderbrantia sepalosa were administered in the traditional way by the healers and their efficacy determined using percent fecal egg count reduction (percent FECR) test. The results indicate that all the herbal remedies had some efficacy against both nematodes and Monezia species of helminths. The group effect against nematodes was significantly different (P=0.002). Compared to an untreated control group, the efficacy against nematodes was 77, 89.8 and 90% for Myrsine afriacana, Albizia antihelmintica and Hilderbrantia sepalosa, respectively, while albendazole had 100% efficacy. The main nematodes encountered included Haemonchus spp., Trichostrogylus spp. and Oesophagostomum spp. With regard to Monezia species herbal remedies performed better than albendazole with an efficacy of 100% compared to 63% for albendazole. The group of sheep treated with Albizia anthelmintica showed a significant increase (P=0.003) in packed cell volume (PCV).

Comparative efficacy of pyrethrum marc with albendazole against sheep gastrointestinal nematodes

The efficacies of pyrethrum marc and of albendazole against experimental sheep gastrointestinal nematode infection were compared. Sheep was infected orally with 10,000 larvae (Haemonchus spp. (60.1%), Oesophagostomum spp. (13.9%), Trichostrongylus spp. (13.2%), Cooperia spp. (8.3%), Nematodirus spp. (3.5%), Strongyloides spp. (0.8%) and Ostertagia spp. (0.2%). Faecal egg count reduction in albendazole-treated sheep was 100% by day 4 following treatment, compared to 37.03%, 31.3%, 38.9% and 51.8% on days 4, 6, 8 and 10 in pyrethrum mare-treated sheep. These reductions were statistically significant on days 8 and 10 post-treatment (p < 0.05). The potential for using pyrethrins for helminth treatment is discussed.

Effects of anthelmintics on Haemonchus contortus (Nematoda: Trichostrongylidae)

The review summarizes and evaluates recent information about the effects of anthelmintics on Haemonchus contortus. The topic is discussed under the headings effects of drugs on the absorptive surfaces, effects of drugs on metabolism, effects of drugs on the neuromuscular system, effects of drugs on developmental stages, anthelmintic efficacy, and resistant strains. Possible future lines of work are suggested in the conclusions.

The incidence of thiabendazole resistance in field populations of Haemonchus contortus on the northern tablelands of New South Wales

A survey was undertaken to assess the incidence of thiabendazole resistance in field populations of H. contortus in sheep flocks on 40 farms distributed throughout the sheep grazing area of the northern tablelands of New South Wales. Treatment with thiabendazole at 66 mg/kg reduced H. contortus ova output by 96-100% in 18 flocks while in the remaining 22 there was a range of responses down to levels where the anthelmintic was without apparent effect. Factors which may contribute to the high incidence of anthelmintic resistance are discussed and the possibility of widespread resistance occurring in other sheep raising areas is considered.