Human health is not only affected directly by parasites that can infect man, but is also affected indirectly by parasites that cause diseases in plants and animals that are food for humans. Of the millions of people who die each year from malnutrition, over half are children under the age of five. The inadequate supply of food on earth and its uneven distribution among developing and developed countries results in starvation and human misery. Predictions of continued increase in human reproductive rates will inevitably result in increasing overpopulation and an exacerbation of food shortages. If agriculture and aquaculture are to be depended upon to supply food for an ever-expanding human population, then the efficiency of food production must increase, in part by reducing loss of food due to parasitic diseases of crops, domesticated animals, and animals derived from the increasingly important aquaculture industry. The use of parasites as biological control agents against crop insects holds much promise for increasing agricultural production.
Veterinary parasitologist care for domesticated animals used for food and for work, as well as caring for our companion animals. Veterinarians play an indirect role in human health when they control parasites in non-human animals that are transmissible to man. Animals used by humans for sport and recreation also require the services of veterinary parasitologists. Pharmaceutical companies are important sources of employment of parasitologists and the development of chemotheraputic drugs to eliminate parasites of animals is of major economic significance. The discovery of antiparasitic drugs for domesticated animals has not only benefited the agricultural industry, but in some cases, has aided humans when these same chemotheraputic agents have been demonstrated to be effective in the treatment of medically important parasites.