Zoonoses are diseases of animals, which can spread to humans. Most episodes involve the transfer, to humans, from an animal or arthropod vector. Fortunately less frequent, but of even greater concern, are those organisms that can establish a life cycle in a purely human population, such as the human immunodeficiency virus.[1]
This section title is from Murphy, and reflects the reality that zoonoses will usually first appear outside the "citadel" of advanced medical science. People that first encounter a new outbreak include local clinicians, pathologists, veterinarians and animal scientists, ecologists, wildlife scientists, as well as local public health officials.
This is the world of shoe-leather epidemiology (the logo of CDC's Epidemic Intelligence Service (EIS) program is the outline of the sole of a shoe with a prominent hole worn in it)
The need is to make advanced resources available to the professionals on the front line, which is one of the roles of the EIS. Field workers may still need to do the initial characterizations, in conditions far from a Biological Safety Level 4 laboratory.
The next phase, after characteriztion, is "what are we going to do about it?"
Finally, resource and bureaucratic factors can interfere with the fonal phases of the discovery-to-control continuum: