3.3. Case-study Results 3.3.1. Years to Resistance 3.3.2. Worm Control

Computer models of parasite epidemiology can be used to investigate integrated parasite management programs and their effects on worm control and anthelmintic resistance. Models for Trichostrongylus, Ostertagia and Haemonchus incorporate worm parasite populations, climate, grazing management, host immunity, drug use and selection for drug resistance, and can be used to explore how treatment frequency, pasture rotation, drug persistency and drug efficacy affect levels of parasitism and drench resistance. A Case Study examining selection by low efficacy drenches is used to demonstrate an application of the models and highlights the difference between model predictions and conventional recommendations to delay selection for drug resistance. In Section 5 (Further Reading) information on more general sheep industry software as well as references to parasite population models can be found