Many people are confused about the relationship between mad cow disease (bovine spongiform encephalopathy or BSE), scrapie in sheep, variant Creutzfeldt-Jakob disease and Classic Creutzfeldt-Jakob disease and other transmissible spongiform encephalopathy diseases (TSEs).
Now we have the foot-and-mouth disease outbreak in United Kingdom and Europe adding to the confusion and heightening the anxiety of consumers in the United States.
My Dairy Channel column of Feb. 1, 2001, discussed the mad cow disease/TSE situation, but I think the current situation could stand further clarification.
Mad Cow Disease (BSE).
Mad cow disease has not been found in the United States.
Mad cow disease is a TSE, thought to have originated from the feeding of animal-based feed products such as meat and bone meal contaminated with brain and/or spinal cord tissue to cattle, possibly from sheep carcasses that may have been infected with scrapie.
Scrapie is also a TSE that affects sheep and goats, but is not known to affect humans.
Mad cow disease is thought to be a “variant” of scrapie and has been linked to a disease in humans, called variant Creutzfeldt-Jakob disease (vCJD). This a very unfortunate name choice because variant Creutzfeldt-Jakob disease (vCJD) is not the same as Classic Creutzfeldt-Jakob disease (CJD), although the symptoms are almost identical.
People all over the world have died of CJD since 1920. CJD affects people (usually over 55) randomly, vegetarians and meat-eaters alike. CJD has not been linked to mad cow disease.
Mad cow is thought to be caused by a type of protein molecule called a prion (not a virus or a bacterium), a causative agent that is very difficult to destroy, but it is not known to be spread directly from animal to animal, or from live animals to humans. This causative agent is not found in the meat of infected animals, only in brain, spinal cord and related tissues.
Sheep in Vermont.
Officials do not suspect the sheep have mad cow disease, or BSE. The flocks of sheep in Vermont that were recently seized by the USDA were originally imported from Europe where they were suspected of being exposed to scrapie.
The USDA has kept these sheep under quarantine ever since they were brought here, not because they were worried about mad cow disease, but because there was concern about the spread of scrapie to other sheep flocks. These sheep were transported to an animal disease diagnostic laboratory for slaughter so brain tissue could be examined for evidence of scrapie infection.
Foot-and-mouth disease.
Now we have an outbreak of foot-and-mouth disease in the United Kingdom and Europe. Foot-and-mouth disease is caused by a virus and is highly contagious.
Foot-and-mouth disease does not affect humans. It affects cattle, sheep, goats and hogs.
The virus can be carried on the hair of animals, on contaminated clothing, footwear and in uncooked meat or other animal tissues. It can be carried on the wind and can be transmitted by birds.
Animals that contract foot and mouth experience abortions, severe weight loss and poor production. Most affected animals do not die.
This is an entirely separate disease from mad cow disease, although lots of people are confused about it. News media have added to the confusion, in some cases mistakenly calling the disease in the Vermont sheep mad cow disease and at other times calling it foot-and-mouth.
Foot-and-mouth disease does not exist in the United States. The last time foot-and-mouth disease existed here was in 1929.
USDA’s Animal Plant Health Inspection Service, U.S. Customs Service and state departments of agriculture have instituted aggressive inspection programs designed to keep foot and mouth disease out of the United States.
People are being questioned about contact with animals in Europe and the U.K. Luggage is being inspected, footwear is being sanitized and certain animal-related products are being seized.
An outbreak of foot-and-mouth in the United States could be devastating to the American livestock industry. You should have a biosecurity program in place on your farm to allow only essential people to have contact with your stock or facilities. Visitors of unknown origin should be kept away from your livestock and facilities.
Anyone who has been to Europe or the U.K. recently should keep all clothing and footwear completely separate from articles used around their own or other peoples’ livestock until these items are cleaned and sanitized.
Other TSEs.
Chronic wasting disease of mule deer and elk in Western U.S. is also a TSE. Some people fear that it could cause a problem in humans or be somehow transmitted to livestock. APHIS officials will not rule out this possibility.
There are five rare TSE diseases of humans (including CJD, vCJD, kuru, Gerstmann-Straussler-Scheinker syndrome and fatal familial insomnia). Animal TSEs include BSE, scrapie, feline spongiform encephalopathy of cats, chronic wasting disease of elk and mule deer, a TSE of mink and others of captive wild ruminants and monkeys in Europe.
So far, none of these animal types, except BSE has been linked to humans.
(The author is an agricultural extension agent in Columbiana County. Questions or comments can be sent in care of Farm and Dairy, P.O. Box 38, Salem, OH 44460.)
To Learn More: Other sources of information on BSE, TSEs and foot and mouth disease:
National Cattleman’s Beef Association’s BSE Web site:
www.bseinfo.org
USDA/APHIS Veterinary Services:
www.aphis.usda.gov/oa/bse.htm
Centers for Disease Control and Prevention:
www.cdc.gov/ncidod/diseases/cjd/cjd.htm
Food and Drug Administration: www.fda.gov/cvm/index/bse/bsetoc.html
Council for Agricultural Science and Technology: TSE Report
www.cast-science.org/
