Bovine Spongiform Encephalopathy (Mad Cow) in the US

Livestock Update, February 2004

W. Dee Whittier, DVM, Extension Veterinarian for Cattle, VA Tech

Bovine Spongiform Encephalopathy commonly known as Mad Cow Disease is the entity that has had the biggest impact on cattle prices and received the most attention nationally in a century. As you undoubtedly know, there was a tentative diagnosis made of Bovine Spongiform Encephalopathy or BSE (popularly called Mad Cow Disease) on December 23, 2003 and confirmed on December 25, 2003. The popular press has covered the story quite extensively and, in my view, generally fairly. There are a number of good information sources about the BSE outbreak. Here are a couple of good ones: www.usda.gov/BSE/ There are links on this page to the latest official statements, etc. Checking this frequently will allow staying up to date on the latest developments and are probably more authoritative than many news media reports. http://www.bseinfo.org/ is the site maintained by the National Cattleman's Beef Association.

The reason this cow disease is national news is that BSE in Europe has been linked to a fatal neurological disease in humans exposed to infective cattle neurological tissues. This disease is called variant Creutzfeldt-Jakob Disease (vCJD), distinguishing it from the Creutzfeldt-Jakob Disease (CJD) that affects 200-300 people in the US each year. An important point is that only about 140 people have ever been diagnosed with the disease worldwide and there has never been a case in the US. In a sense, this disease could be rated as the most over-reacted-to disease as well since many animal associated diseases (Salmonella for example) kill many times this number yearly.

What do we know about this case? (As of 1/14/04)

The case was a 6-1/2 year old Holstein cow sold for slaughter by a 4000 cow dairy in Mabton, Washington. She was slaughtered on December 9 and, because she was a downer, had tissues collected for BSE testing. Testing on December 22 classified her as a suspect. Additional testing at Ames, Iowa and finally in the UK confirmed her diagnosis as having BSE. Records indicated that this cow was imported from Alberta, Canada in 2001 along with 81 others. DNA testing of the cow when compared to her sire and daughter confirmed her Canadian origin and identity. USDA is making a point of the 6 1/2 age, since she was a calf in 1997 before the ban on feeding ruminant-derived protein to ruminants began in North America in 1997. This allows them to say that this cow was probably infected before the ban and that current safeguards are working.

What is the fallout?
1) Follow-up: The herd of origin (USDA folks call this the index herd) is quarantined. The cow has two living offspring: one is a yearling heifer in the index herd; the other is a bull calf that is lost in a calf ranch that is also quarantined. A vigorous hunt is on for the cattle imported with the affected cow. Beginning on December 24, meat from the slaughter facility where the cow was harvested was recalled. Since this was 13 days after the harvest, the odds are most of the beef was eaten before the recall but the parts believed to be infective were not marketed because of her suspect status. Mostly the recall amounted to retailers informing customers of the event. The phrase the USDA is using to describe the recalled meat and, in fact, the whole US beef supply is that it poses "near zero risk".

As the workup of the situation has continued, a decision was made to depopulate the 450 bull calves at the calf ranch where the infected cow's calf went. On January 9, 2004 USDA announced it would remove a limited number of cows from the index herd in Mabton, Washington. USDA will most likely remove approximately 130 animals from this herd that contains approximately 4,000 dairy cows. To summarize results thus far from the epidemiological investigation:

Of the 81 cows that came from Canada with the positive cow:

• One is the positive cow
• Two are under a hold order at a premises in Mattawa, WA
• USDA believes 7 may have gone to another dairy and is working to determine if those animals are still there
• Nine are in the index herd
• Potentially some of the remaining cows that came in that shipment are on the index premises, but at this time the identity of these animals has not been confirmed.

2) Exports: Almost immediately after the public announcement on December 23 countries began to suspend beef trade with the US. Among these are major importers of US beef including Japan, South Korea, Mexico, Hong Kong, Russia, Taiwan, Singapore, Malaysia, and South Africa. This has huge economic consequences for the beef industry. The hope is that this cow being born before the ban and being an imported cow from Canada will make these countries open their borders sooner rather than later.

The USDA is actively working with major markets like Japan and Mexico. The political side of this issue promises to be interesting and frustrating.

3) Domestic Beef Consumption: Here the news seems good. Most beef eaters say they are convinced the supply is safe and that they will continue to eat beef. Of course, there is an initial reaction by everyone from consumers to retailers to purveyors to packers but overall, most experts don't expect a large, long-term decline in domestic beef consumption. Indeed, there should not be a decline as nearly all experts agree that there is "near zero risk" of getting vCJD from eating beef produced in the US.

4) Beef prices: Here the news is mixed and still uncertain. As futures and live fed cattle prices stabilized, it appears that $15 to $20 per hundred came off of the price of fed cattle on a live weight basis. Much of this is probably due to loss of export markets. Live slaughter cattle this week have sold in the mid 70's ($70 per hundredweight), 5-weight feeder cattle in the high 90's, 6 weights in the low 90's and high 80's, and cows (almost unchanged from Pre-BSE) in the 30-50 range. While young cattle prices are down from very high levels this fall these are still prices compatible with profits for Virginia producers.

5) Regulation changes: Some important changes were announced on December 30, 2003.

Seven changes were announced:

Downer Animals. Effectively immediately, USDA banned all downer cattle from the human food chain. USDA will continue its BSE surveillance program.

Product Holding. USDA Food Safety and Inspection Service inspectors will no longer mark cattle tested for BSE as "inspected and passed" until confirmation is received that the animals have, in fact, tested negative for BSE. To prevent the entry into commerce of meat and meat food products that are adulterated, FSIS inspection program personnel perform ante- and post-mortem inspection of cattle that are slaughtered in the United States. As part of the ante-mortem inspection, FSIS personnel look for signs of disease, including signs of central nervous system impairment. Carcasses from animals that pass inspection but who have signs of Central Nervous System disease will now be held until testing clears them of BSE.

Specified Risk Material. Effective immediately upon publication in the Federal Register, USDA will enhance its regulations by declaring as specified risk materials skull, brain, trigeminal ganglia, eyes, vertebral column, spinal cord and dorsal root ganglia of cattle over 30 months of age and the small intestine of cattle of all ages, thus prohibiting their use in the human food supply. Tonsils from all cattle are already considered inedible and therefore do not enter the food supply. These enhancements are consistent with the actions taken by Canada after the discovery of BSE in May.

Advanced Meat Recovery. AMR is an industrial technology that removes muscle tissue from the bone of beef carcasses under high pressure without incorporating bone material when operated properly. AMR product can be labeled as "meat." FSIS has previously had regulations in place that prohibit spinal cord from being included in products labeled as "meat." The regulation, effective upon publication in the Federal Register, expands that prohibition to include dorsal root ganglia, clusters of nerve cells connected to the spinal cord along the vertebrae column, in addition to spinal cord tissue. Like spinal cord, the dorsal root ganglia may also contain BSE infectivity if the animal is infected. In addition, because the vertebral column and skull in cattle 30 months and older will be considered inedible, it cannot be used for AMR.

In March 2003, FSIS began a routine regulatory sampling program for beef produced from AMR systems to ensure that spinal cord tissue is not present in this product. In a new interim final rule, establishments have to ensure process control through verification testing to ensure that neither spinal cord nor dorsal root ganglia is present in the product.

Air-Injection Stunning. To ensure that portions of the brain are not dislocated into the tissues of the carcass as a consequence of humanely stunning cattle during the slaughter process, FSIS is issuing a regulation to ban the practice of air-injection stunning.

Mechanically Separated Meat. USDA will prohibit use of mechanically separated meat in human food.

Mandatory Cattle Identification. While many cattle in the United States can be identified through a variety of systems, the Secretary also announced that USDA will begin immediate implementation of a verifiable system of national animal identification. The development of such a system has been underway for more than a year and a half to achieve uniformity, consistency and efficiency across this national system.

Virginia producers will feel the effects of these rules but they will not be burdensome. I understand the ban on slaughtering downer cows and agree with it but wish there had been an announcement to pay producers for transporting down cows to diagnostic labs so they could be tested for BSE. I encourage Virginia producers to take downer cows to state Veterinary labs on their own. The cost of the necropsy is not that much different than burying the animal. The other five regulation changes that will affect beef slaughter and processing will increase modestly the costs of slaughtering and processing cattle and the producer will ultimately pay this cost.

Mandatory cattle ID has been on the horizon for a while and we know some about the system. I hope the speeded implementation means some resources to get it done right and not an increase in errors, confusion and complications. My advice to producers is to recognize this change as inevitable and to be as cooperative as possible with those who are charged with implementing the program.

Final thoughts: We'd all lived with concern for some time that BSE would be found in the US and now it has happened. The fact that this case was a cow imported from Canada may prove to be a real blessing to us, but is terrible news for the already downtrodden Canadian beef industry. There is a legitimate concern that meat and bone meal produced in Alberta in the mid to late 1990's was contaminated with BSE agent. If so, there may be more cases in Canada. We can certainly expect that importation of cattle and beef from Canada to the US will be scrutinized and curtailed for a long time.

The USDA continues to emphasize its position that the only way BSE occurs is from cattle eating products containing neural tissue that is infected with the infectious agent (a prion). If this is true, the further we get from the 1997 ban on feeding ruminant-derived protein to ruminants, the greater the chance that we will never have a purely US case of this disease that has an incubation period of 3-8 years.

I certainly agree with the USDA that the risk of a human case of variant Creutzfeldt-Jakob Disease (vCJD) in the US resulting from eating US beef is "near zero".

Now a final thought that is purely mine (but some scientists acknowledge its validity). Creutzfeldt-Jakob Disease (CJD) in people is a sporadic disease that occurs in people about 60 years old but has not been associated with any risk other than age. About 1 person in a million gets it each year worldwide. Think of it like cancer; not caused by an infectious agent. Its occurrence is spontaneous. Where did the original BSE that got into the British meat and bone meal supply come from? At first, the thought was that it was a mutation of the sheep spongiform encephalopathy called scrapie, but most experts don't now believe that. I believe that the original BSE came from a cow or cows that got the disease spontaneously, then got into the meat and bone meal supply. Maybe the incidence of this spontaneous disease is only one in a billion. Could we have a case of spontaneous BSE in the US? Were these Canadian cases spontaneous? For the sake of our industry I hope not, but think we ought to consider the possibility. Such a happening would not mean that the beef supply is more than an infinitesimally amount less safe, but it will surely be hard to explain. And as beef futures behavior after the discovery of BSE aptly proved, perception is reality.

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