Circumventing natural barriers to infection (the skin and gastrointestinal tract)
promotes the transmission of infectious diseases from animals to humans.
Animal viruses within the body of the person who receives a xenotransplant could
become airborne, infecting scores of other people. Viruses that are harmless to the animal
host can be deadly when transmitted to humans. For example, Macaque herpes is harmless to
Macaque monkeys but fatal to humans.
Scientists have continued to discover new viruses in primates and pigs and there
is no way to screen for still unknown viruses. Performing a xenotransplant from an
animal infected with an unknown virus would infect not only the patient.
Non-patients as well could be exposed to a host of new animal viruses which might remain
dormant for months or years before being detected.
By law xenotransplantation could be considered illegal since it affects unintended
people and is therefore a form of involuntary human experimentation which violates US laws
and United Nations charters.
It is impossible to breed "germ free" animals as proponents of
xenotransplantation propose since no animal can remain completely free of parasites
or endogenous viruses. In fact, genetically engineered animals are more susceptible
to a host of diseases because they have weaker immune systems.
Breeding animals for xenotransplantation creates a host of environmental problems,
including soil and groundwater contamination associated with disposal of animal waste and
the carcasses of genetically modified animals and their offspring.
There is virtually no, or at best weak, oversight of transplantation