Anthelmintic resistance in parasitic nematodes of small ruminants is widespread and, in some parts of the world, threatens the sustainability of sheep production. The mechanisms whereby parasitic nematodes become resistant to anthelmintics, particularly ivermectin, remain to be determined. The majority of studies to date have investigated target site mutations; relatively little attention has b...

Sixty-five sheep farms in the northern provinces of Buenos Aires, Entre Rios, Corrientes, Cordoba and Sante Fe were used in this survey on anthelmintic resistance. Anthelmintic groups tested were the benzimidazoles, levamisole, the combination levamisole + benzimidazole product and the avermectins. The overall level of resistance was 46% of properties, with resistance to the individual drug gro...

Haemonchus, Trichostrongylus, Ostertagia and Nematodirus worm populations of Angora goats, based on differential egg counts, are considered in relation to climatological and topographical data. Egg counts indicated that the estimated worm populations in goats that experienced wet circumstances were higher than those exposed to dry conditions. Wetness was assessed by relating spring, summer, and...

The cumulative total helminth parasite burdens of ranch calves during their first seven months of life on the North-eastern Mountain Grassland of South Africa were determined during two consecutive years. Trichostrongylus axei was the most abundant nematode parasite followed by Cooperia spp. and Ostertagia ostertagi. Haemonchus spp. occurred in relatively low numbers and its development was sig...

The effects of tannins on adult populations of Haemonchus contortus, Trichostrongylus colubriformis and Teladorsagia circumcincta in goats are characterised mainly by a decrease in egg excretion without any significant changes in worm number. In contrast, the impact of tannins on T. colubriformis or T. circumcincta third-stage larvae (L3) is associated with a significant reduction in worm estab...

This paper reports the sequence of sheep interleukin 23A (p19), and shows that it shares 98% identity with bovine IL23A, 85% with human and 76% with mouse IL23A. It also reports the existence of two allelic variants that differ largely within the region encoding the amino terminal polypeptide signal sequence. An optimized RT-qPCR assay was used to quantify IL23A transcripts in sheep infected wi...

The prevalence of gastric nematodes in 151 goats on Grand Canary Island is around 56%, with a mean burden of 691 worms/animal. No significant differences of prevalence and intensity were found between the four isoclimatic areas of the island [dry-desert (DD); dry-steppe (DS); temperate-mild (TM); temperate-cold (TC)]. Five nematode species were identified, the most commonly-occurring being Tela...