One Health - Группа авторов

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from a common ancestor, some doctors attempted to trace the evolutionary history of disease by examining its manifestations in different animal species. The most famous participant was Eli Metchnikoff, whose Nobel Prize-winning theory of phagocytosis was inspired by evolutionary thinking (Tauber, 1994). Animal diseases were also important in the development of germ theories of disease. In Britain, their acceptance was precipitated by the devastating 1865–1867 epidemic of cattle plague, whose pathology and epidemiology was subjected to scientific investigation by medical doctors (Worboys, 1991). Elsewhere, seminal research on germs focused on the nature, prevention and spread of animal diseases. In France, Louis Pasteur produced vaccines against chicken cholera, anthrax and rabies. His German counterpart Robert Koch investigated anthrax and tuberculosis, as well as tropical animal diseases which inspired his concept of the carrier state.

      Vets made important contributions to all these investigations, which used a myriad of animals for the purposes of research, diagnosis and the production of vaccines and sera (Bynum, 1990; Wilkinson, 1992; Gradmann, 2010). Existing aetiological connections between human and animal diseases were redefined in terms of germs. A new category of diseases, the zoonoses, emerged to incorporate these and parasitic diseases like trichinosis, for which the life cycle and spread via the meat trade were worked out from the mid-1850s to the 1870s by Virchow, among others. They formed the focus of a new field of veterinary public health (VPH).

      Today, Darwinism, the discovery of germs, and the rise of bacteriology, are heralded as key events in the development of One Health approaches. Closer scrutiny, however, suggests that these events had the reverse effect. In redefining disease as the straightforward product of infectious agents invading susceptible bodies, they downgraded the importance of the environment to health (Worboys, 2000). In bringing human and animal biology closer together, they heralded changes – described below – in the epistemic status of experimental animals, from representatives of particular species to ‘model’ humans. In inspiring the mainstream adoption of the term ‘comparative pathology’, they marked the compartmentalization of animal disease from mainstream medicine, while the emergence of VPH resulted in a newly competitive relationship between doctors and vets over control of zoonotic diseases (Hardy, 2002; Waddington, 2006).

      Animals and Humans in 20th-century Medicine

      The 20th century was characterized by considerable ambiguity in the perceived relations between humans and animals in health and disease. This was particularly apparent in the status of animals within medical research, which underwent an important epistemological shift around the turn of the 20th century. Earlier, scientists had drawn on a diversity of species, including but not confined to earthworms, horses, birds, frogs, pets, zoo animals, horses, livestock and fish. They were usually familiar with these animals, having encountered them in farming, field sports, natural historical pursuits, zoos, and urban streets populated with horse-drawn transport, stray dogs, and livestock for sale and slaughter (Kete, 2007). The sheer ubiquity of animals made it easy to acquire them for experiment in life, and dissection after death. The resulting research was truly comparative. It sought to build general truths through examination of similarities and differences between animals. Acknowledging, with a nod to evolution, that species differences were to be expected, researchers did not assume that a finding was true of all animals until they had demonstrated it in a host of different species (Logan, 2002).

      Subsequently, however, scientists moved away from demonstrating generality to presuming its existence. Animal diversity became a confounding factor rather than a research strength. It can be no coincidence that as towns grew larger, as animals disappeared from the streets and urban upbringings became the norm, scientists began to restrict their gaze to a handful of animal species that could be kept within the laboratory. Paralleling the rise of standardization and mass production within industry, scientists entered into the mass production of standardized laboratory animals whose features could be quantified or mechanically assessed. By the interwar period, with diversity reduced further through standardized husbandry and environments, these animals formed the mainstay of scientific work on cancer, genetics, and drug standardization. Their uses continued to expand throughout the second half of the century. By then, however, biomedical scientists were no longer engaging with them as animals, but as functional equivalents or ‘models’ of the human body whose scientific legitimacy was underpinned by the theory of evolution (Clause, 1993; Logan, 2002; Löwy, 2003; Rader, 2004; Kirk, 2008).

      One interesting inversion of this state of affairs occurred in the context of veterinary medicine in the later 20th century. The increasing importance of human relationships with pets, and owners’ greater willingness to invest financially in this relationship, resulted in the growing veterinary use of insulin treatment, orthopaedic surgery and transplant surgery. Originally these technologies were trialled on animal models before entering human medical practice. Now, their use in animal patients was informed by clinical trials and experiences in humans, who effectively became the models (Degeling, 2009; Gardiner, 2009; Schlich et al., 2009).

      The increasing use of standardized animals within medical research caused some vets in Europe and North America to carve out a new role in caring for them. In the light of continuing public concerns about animal

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