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VETERINARY PUBLIC HEALTH

In 1999, a study group on veterinary public health (VPH), convened jointly by the World Health Organization (WHO), the Food and Agriculture Organization of the United Nations (FAO), and the Office International des Epizooties (OIE), and including twenty-eight experts from eighteen countries, defined veterinary public health as "The contribution to the complete physical, mental, and social well-being of humans through an understanding and application of veterinary medical science."

The contribution of veterinary science to human health has been fundamental and sustained over millennia. It is not generally appreciated that this contribution pertains not only to livestock and food production, animal power, and transportation, which have laid the basis for most urban societies around the world. The study and management of animal diseases have also laid the basis for much of what is known about the dynamics and management of infectious human diseases, and has aided in the promotion of environmental quality.

Calvin Schwabe, one of the most important figures in veterinary public health in the twentieth century, has traced and documented the roots of the healing professions to healer-priests in the Nile Valley. Because cattle and horses were so important for sustainable food supplies, transport, and the military cohesion of ancient empires, these animals were very carefully observed and husbanded. In addition, the integrative view of healers in Egyptian and Greek cultures allowed lessons of comparative anatomy and diseases learned from the slaughter, hunting, and sacrifice of animals to be applied readily to the healing of primates. Even today, both human and veterinary medical practice draw upon the same pool of comparative, multispecies biomedical research.


RELATIONSHIPS TO PUBLIC HEALTH
If we narrow the focus of veterinary public health to those aspects that are directly pertinent to the practice of public health, rather than to human health in general, three broad areas of involvement become clear. Although these are sometimes characterized in historical terms, or in terms of "rich country-poor country" divisions, these different facets of veterinary public health are in fact ongoing, in complementary and often synergistic fashion, in most parts of the world.
Veterinary public health, in the first place, grows from its relationship to food production, usually by investigating and controlling animal diseases that threaten either food supplies or animal transportation and labor, which are essential elements in food production throughout much of the world. A second facet of veterinary public health relates to control of the transmission of zoonotic diseases, either directly or through foods. This is reflected in a wide array of activities, including research and control of infectious agents in meat and milk, rabies vaccination campaigns (both of wildlife and domestic animals), monitoring arboviruses and Lyme borreliosis in populations in wildlife, and hydatid disease control programs.

These first two facets are widely recognized as veterinary public health activities. The third facet, however, is less widely known. In many parts of the world, veterinarians, because of their knowledge of animal diseases, as well as the ecological, economic, and human cultural contexts of these diseases, have been instrumental in developing and implementing new methods of promoting sustainable public health that are ecosystemically grounded, culturally feasible, and economically realistic.

Many veterinary public health activities are reflected in the nature of veterinary involvement in public health institutions in North America and Europe. Veterinary activities involving disease control and health management in animal populations, and their integration of clinical, pathological, and epidemiological practices, often preceded similar activities in human medicine by decades, or, in some cases, centuries. It was in the area of food hygiene, however, that veterinary contributions to public health were first formally institutionalized. In Europe, particularly in Germany, veterinarians in the nineteenth and twentieth centuries were integral to the development of food hygiene laws and meat inspection systems, initially to curb large outbreaks of trichinosis.

In the aftermath of World War II, the U.S. Public Health Service's Communicable Disease Center, later named the Centers for Disease Control and Prevention (CDC) established a veterinary public health unit. James Steele, the first chief public health veterinarian in the CDC, was also active in promoting the veterinary public health unit in the World Health Organization. Martin Kaplan, another American veterinarian, became the first director of this unit. Both men expanded the traditional European emphasis on veterinary-directed food-safety programs to include investigations into the epidemiology and control of zoonoses. The 1960s and 1970s saw a reduced interest in veterinary public health, particularly in North America, because major infectious diseases were thought to be under control, and public health epidemiologists focused their efforts largely on chronic diseases such as heart disease and cancer. Although veterinarians were deeply involved in improving the understanding of these conditions by studying them in animal populations, many scientists and laypeople still had an image of veterinary public health practitioners as meat inspectors in a slaughterhouse. In 1975, the veterinary public health unit within the CDC was officially disbanded. Even during this time, however, several veterinarians were making strong contributions to public health through the CDC. Joe Held, a graduate of the Epidemic Intelligence Service of CDC, went on to become director of the National Institutes of Health Division of Research Services, Assistant Surgeon General, and director of the Pan American Zoonoses Center in Argentina.

Some within the CDC have argued that veterinary skills have been put to much broader use since the disbanding of the veterinary public health unit. In 1997, Peter Schantz, a veterinary parasitologist at CDC, documented that there were fifty-nine veterinarians at CDC assigned to eleven different centers, institutes, or program offices. Besides programs carrying out research and control of zoonotic diseases, veterinarians worked as epidemiologists and research scientists on other infectious diseases—including HIV/AIDS (human immunodeficiency virus/acquired immunodeficiency syndrome)—and on the national immunization program, environmental health, occupational health, and international health.

It was really only when infectious diseases began to reemerge as a global problem in the 1980s and 1990s that veterinary public health came back into prominence. This is largely because veterinary education, traditionally oriented to farm livestock, has been at the forefront of understanding the epidemiological features of infectious diseases in populations. It is no accident, for instance, that the protective effects for a population of vaccinating part of that population is termed a "herd effect." Furthermore, the wide scope of veterinary education lends itself well to studying and controlling zoonotic and food-borne illnesses, which became important areas of interest at the beginning of the twenty-first century.

Animal diseases may threaten human health in two ways: (1) they may threaten the animal populations that serve as food, transportation, or traction power in the fields; and (2) through zoonotic diseases, that are transmissable to humans.