Research needs and priorities for ruminant internal parasites in the United States.

The management-chemotherapy approach is currently the most applicable means of effectively and practically controlling parasites of ruminants. Knowledge of regional patterns for major ruminant parasites, especially seasonal transmission dynamics, promises to lead to major improvements in management-chemotherapy systems. This knowledge also provides the fundamental context for design of new integrated control strategies that include other approaches such as immunization, chemical and biological control, and the interaction of environmental, physiologic, and nutritional factors. Greatly needed is a change in the protracted government regulatory process that obviates the availability of new, more effective drugs until years after they are available in other developed nations and that creates a dearth of "minor species, minor use" antiparasitic compounds. It is necessary to recognize both the need for product safety and the realities of investment limitations in the pharmaceutical industry. Also needed are new formulations and better methods of mass treatment for inaccessible herds of ruminants that will allow flexibility in strategic treatment programs based on seasonal transmission and other factors. More reliable cost-benefit assessments, more sensitive diagnostic indicators, and better knowledge of pathophysiologic mechanisms of damage by parasites will assist greatly in identifying the economically important effects against which economical control programs can be targeted. The opportunities for development and evaluation of novel prophylactic, diagnostic, and management approaches for animal parasitism are close at hand if the spectacular advances in molecular biology, immunology, computer science, and ecologic methodologies are assimilated in present research efforts. Although the emphasis of this report is on applied research and identification of approaches for the immediate future, the importance of more basic research on animal parasites and discoveries in other areas of modern biology and medicine are recognized as the essential pacesetters of the future. There is increasing concern by agricultural research workers that renewal of this base of fundamental knowledge is greatly needed. In this context, studies on the physiology, behavior, antigenicity, and genetic makeup of parasites, protective host responses, and mechanisms of tissue destruction and invasion by veterinary parasites are essential. Veterinary parasitologists must study host-parasite interactions directly with minimal reliance on rodent model systems; although this has disadvantages it offers special opportunities for research that is concurrently applied and fundamental. While the livestock industry can expect continuous progress on current problems, a long-term investment in basic research must be made for the future.