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diseases, animal 557

been exposed to the disease. Can any moral being imag- banning use of the waste products of slaughterhouses in
ine such a draconian solution if the animals exposed to both hamburger for human consumption and in cattle
a potential contagion were Homo sapiens, rather than feed could stop any possible outbreak, yet commercial
ungulates? Similarly, wild bison that stray beyond the pressures have slowed or prevented such moves. Still, the
borders of America’s Yellowstone National Park are sum- total number of BSE human victims numbers less than
marily slaughtered by agents of the state of Montana on twenty, and there is little likelihood of an outbreak or of
the grounds that these animals might act as reservoirs for a human contracting BSE through eating regular beef in
the cattle disease brucellosis.The irony in this case is that the form of roasts or steaks.
brucellosis is a disease that evolved in Old World bovids Hanta virus is a rodent-borne viral pathogen.There is
and was introduced into America along with cattle. No actually an entire class of Hanta-like viruses in a variety
bison has ever been demonstrated to show the symptoms of murid rodents. The one described as Hanta virus
of brucellosis, yet the fact that a low percentage of bison appears to have only one species, deer mice, Peromyscus
test positive for exposure to the pathogen is deemed suf- maniculatus, as its primary host, where it does not appear
ficient reason to kill them. to cause significant health problems. In humans, how-
The response to so-called mad cow disease, more ever, this virus causes pneumonia-like symptoms that
properly called bovine spongiform encephalopathy result in death about 50 percent of the time.This disease
(BSE), is even more absurd. BSE appears to be one of a is well known to indigenous peoples of the American
group of related pathological conditions that may be Southwest and may be one of the reasons that traditional
caused by prions, which appear to be protein molecules Dine (Navajo) people destroy a Hogan after a person has
capable of self-replication. Other diseases in this category died in it. In recent years this disease has caused a minor
are scrapie in sheep, and kuru and Creutzfeldt-Jakob panic in the United States because deer mice are a wide-
syndrome in humans. Such pathological conditions spread common rodent. Hanta does not appear to be
impact the central nervous system (CNS) and gradually transmissible among humans so it is unlikely to ever
destroy the brain. The damage to the CNS is what pro- become a true epidemic. The number of recorded cases
duces the symptoms that have disrespectfully led to this in the United States is less than 200 since the Center for
condition being designated as mad cow. A far better and Disease Control (CDC) has been keeping records.
more accurate term would be acutely distressed cow. To summarize, the major environmental and health-
These apparently prion-based conditions are not directly related problems in humans result primarily from close
communicable and can only be passed through con- association with domestic animals.This continued prox-
sumption of CNS tissue including brain and spinal cord. imity has allowed several diseases to jump from their
The only reason these conditions appeared to spread in ungulate or avian hosts and cross the species barrier into
the United States and England is because slaughter- humans.
houses in those countries use “wastes” remaining after
Raymond Pierotti
butchering to be ground up and added to cattle feed as
a protein supplement.
In humans it is obvious that only through consuming Further Reading
CNS material can humans become infected. Outbreaks of Alchon, S. A. (2003). A pest in the land: New World epidemics in a global
kuru in New Guinea are clearly related to the cultural tra- perspective. Albuquerque: University of New Mexico Press.
Cockburn,A. (1967). Infectious diseases:Their evolution and eradication.
dition of consuming the brains of other humans as part Springfield, IL: Thomas Press.
of a cannibalistic tradition. In England, BSE-type syn- Crosby, A. (1972). The Columbian exchange: Biological and cultural con-
sequences of 1492. Westport, CT: Greenwood Press.
dromes have shown up in humans who consumed low-
Diamond, J. (1997). Guns, germs, and steel. New York: W. W. Norton
grade commercial hamburgers. It seems obvious that and Co.