Gastrointestinal Nematode Control Programs with an Emphasis on Cattle

Nematode infections in ruminants can be managed with numerous control strategies. By necessity, many current methods of control are reactionary as the parasites acquire resistance to anthelmintics. However, as new classes of compounds with new modes of action become available, these chemistries must be used in a way that maximizes efficacy but also prolongs the life of the compounds. This practice should include managing the herd genetics and immune responses against the parasites in combination with the judicious and timely use of anthelmintics. Future programs may also control helminths with combined approaches, such as pasture larval control (using fungi), providing forages with antiparasite activity, and managing host genetics and immunity. These programs must be integrated so they do not rely on any single method, because the parasites have an astounding ability to evolve mechanisms to elude the current therapy. A hallmark of any parasite-host system is the extraordinary ability of the parasites to adapt to new challenges. Continued cost-effective parasite management must also show a level of high adaptability.