Numerous history books tell the gory stories of small pox, typhus, measles points out that human history is filled with the catastrophic consequences of emerging infectious diseases. While these diseases have been chronicled in one way or another, Williams writes that there haven't been many "systematic studies of emerging infectious diseases of wild animals and their effect on human populations."
The lack of studies was probably due to the belief that humans didn't catch anything from animals, but as research got better, people began to understand that animals could serve are "natural reservoirs for diseases that can be extremely virulent among humans," Williams writes, citing the influenza virus that is now understood to involve an "exchange of genes between the viruses of wild and domestic birds, pigs and humans."
The report explains that "emerging infectious diseases of wildlife are associated with the 'spill-over' of pathogens from domestic animals to wildlife populations; with the translocation of host or parasites by human intervention; and with events that have no human or domestic animal involvement, such as global warming or floods." Williams explains that, as an example, that "brucellosis was probably co-introduced to America with cattle," (cattle served as a reservoir for the infectious disease) but now is resident in Yellowstone bison (which are the new reservoir) and neighboring ranchers worry about a reverse transfer. To prevent any spread, the ranchers shoot any bison that wander out of the park during the winter in search of food.
Humans also introduce domesticated animals to areas where wildlife was previously unexposed to them. Williams uses the example of "the translocation of wildlife. .in conservation efforts or for agriculture or hunting. He quotes Dr. Peter Daszak of the University of Georgia's Institute of Ecology and Department of botany: "The introduction of animals to new geographic regions and the co-introduction of their pathogens is a serious problem . . .For example, avian malaria on Hawaii is thought to have caused the extinction of a number of native species and was originally introduced with exotic, alien birds."
