Resistance of Trichostrongylus spp. (Nematoda) to benzimidazole in Algerian cattle herds grazed with sheep.

Drug resistance in cattle strongyles to anthelmintics is rarely described in Europe and in the Mediterranean areas. The faecal egg counts are usually low in cattle, and detection of resistance may be particularly difficult. We used the method of twice-repeated treatments and used various estimations of efficacies in order to detect cattle strongyle resistance to benzimidazoles. Resistance was found in two farms among eight that were studied. Trichostrongylus axei was the resistant species in one farm whereas Trichostrongylus sp. was found in another farm. In both farms, there were sheep flocks with a history of strongyle benzimidazole resistance and practice of alternate or mixed grazing with cattle.