The discovery Dec. 23 of a cow infected with bovine spongiform encephalopathy (BSE), or mad cow disease, in Washington state raises many questions about the disease and how it may be handled now that it has shown up in the United States.
The central veterinary laboratory in Weybridge, England, confirmed the preliminary result Dec. 25.
The animal, a Holstein cow, was culled due to paralysis as a result of calving complications. The animal was sampled for BSE because it was a “downer” prior to slaughter.
The farm involved is a large dairy operation with approximately 4,000 adult animals at two locations, one in Mabton, Wash., and the other in Grandview, Wash.
The animal in question was purchased into this herd in October 2001. An investigation is underway to determine the origin of the animal.
Background. BSE became a serious cattle disease in the United Kingdom (UK) in the early 1990s, peaking in 1993 at almost 1,000 cases per week.
This outbreak is thought to have been the result of feeding scrapie-infected sheep meat-and-bone meal to cattle.
According to the Centers for Disease Controls’ National Center for Infectious Disease, there is strong evidence and general agreement that the outbreak in UK was amplified by feeding rendered bovine meat and bone meal to young calves.
The nature of the transmissible agent is unknown.
The currently most accepted theory is that the pathogen is a modified form of a normal cell surface protein known as a prion. This prion is thought to be able to withstand high temperature and be resistant to most known disinfectants.
Earlier in 2003, a single beef animal in Canada was confirmed to have BSE, causing beef export barriers against Canadian beef and live cattle.
Brain disorder. BSE is strongly linked to a rare, degenerative, fatal brain disorder known as new variant Creutzfeldt-Jakob Disease (vCJD) in the UK and Europe.
As of Dec. 1, 2003, a total of 153 cases of vCJD had been reported in the world: 143 from UK, six from France and one each from Canada, Ireland, Italy and the United States. (The one from the United States was reported in a patient who lived in the UK before moving to the States.)
Almost all the 153 vCJD patients had multiple-year exposure in the UK between 1980 and 1996 during the large UK outbreak of BSE.
There has never been a case of vCJD that did not have a history of exposure within a country where BSE was present.
It is believed that people who have developed vCJD became infected through consumption of cattle products contaminated with the agent of BSE.
There is no known treatment of vCJD and it is invariably fatal.
The incubation period of vCJD is unknown, but is thought to be many years or decades.
In contrast to classic CJD, vCJD affects younger people and has markedly different symptoms.
Detection efforts. BSE detection efforts in the U.S. have been ongoing since May 1990, when severe restrictions were placed on importation of cattle and cattle by-products into the United States.
The USDA’s Animal Plant Health Inspection Service, Food Safety Inspection Service, the U.S. Food and Drug Administration, and the Centers for Disease Control cooperate to monitor for the presence of BSE and vCJD.
These agencies have collaborated to set up a surveillance program to include:
1) Prohibitions and/or restrictions on certain animal and product imports.
2) Ongoing surveillance for the disease in the United States.
3) Preparation of an emergency response plan in the event of an introduction into the U.S.
4) Ongoing educational efforts.
Transmission to humans. According to the latest scientific evidence, the tissues most likely to contain the BSE prion are brain, spinal cord, and the ileum (lower small intestine), all of which are typically (and were in this case) removed from the carcass at slaughter.
Therefore, according to USDA’s Animal Plant Health Inspection Service, the meat produced were cuts that would not be expected to be infected or have any adverse public impact, but were recalled out of an abundance of caution.
vCJD is not transmissible directly between humans.
The animal was slaughtered and processed at Vern’s Moses Lake Meats, Moses Lake, Wash., which is voluntarily recalling approximately 10,410 pounds of raw beef that may have been exposed to tissues from the infected animal.
The beef subject to this recall (20 carcasses) was produced Dec. 9. It was then shipped to Midway Meats of Centralia. Wash., and several establishments where it was further processed.
These establishments were Williamette Valley Meat Co., Portland, Ore., and interstate Meat Dist. Inc., Clackamas, Ore.
What now? As of Dec. 26, Washington state officials have put a hold order on the farms, restricting the movement of animals.
Food Safety Inspection Service has enforcement, investigation, and analysis officers at the three facilities and they are identifying and verifying the distribution of the product.
The inspection service is continuing its investigation to ensure all distribution of the beef products is correctly identified.
It has designated this recall as Class II, due to the extremely low likelihood that the beef being recalled contains the infectious agent that causes BSE.
There is no known link between milk from BSE-infected animals and vCJD in humans.
More questions. Consumers with food safety questions can call the USDA Meat and Poultry Hotline at 888-MPHotline.
The hotline is available in English and Spanish and can be reached from 10 a.m. to 4 p.m. Monday through Friday.
Recorded food safety messages are available 24 hours a day.
Further information will be posted at www.usda.gov as it becomes available.
(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.)
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