Current Status of Anthelmintic Resistance in Gastrointestinal Nematodes of Cattle and Recommendations for Sustainable Control

摘要

Beginning with phenothiazine in the 1950s, followed by the benzimidazoles in the 1960s, the imidazothiazole/tetrahydropyrimidines in the 1970s and the avermectin/milbemycins (AM) in the 1980s, a new class of anthelmintics was introduced into the marketplace each decade. This arsenal of highly effective and relatively inexpensive drugs led to recommendations for parasite control that were based almost solely on the frequent and or strategic use of anthelmintics, the goals of which were to maximize livestock health, productivity, and profitability. Though this approach was highly successful for a number of decades, we are now experiencing ever-increasing levels of anthelmintic resistance in all drug classes, involving virtually all of the most economically important parasites of all livestock species. Resistance in parasites of cattle was slower to develop than in the small ruminant and equine sectors, but over the past decade we have seen a rapid escalation in the levels and distribution of anthelmintic resistance in parasites of cattle worldwide.