Europeans and the news media are quite concerned about mad cow disease. So, we in agriculture need to know something about it also, even though it is still a European problem.
Europe, but not the United States, have been burdened with concerns of mad cow disease, or bovine spongiform encephalopathy, since October 1996. From then until early December 2000, 87 human cases of Creutzfeldt-Jakob Disease, a human disease similar to mad cow disease, have been reported in the United Kingdom, with three in France and a single case in the Republic of Ireland.
Other brain degenerative diseases have been with us for some time, but the difference between those and CJD is that CJD in humans seems to be strongly linked to exposure, probably through eating beef, to mad cow disease in cattle.
Assuming there is a relationship between eating beef and Creutzfeldt-Jakob Disease in humans, as most scientists think there is, it makes sense that the highest incidence of mad cow disease is in one place, namely Europe, and especially the United Kingdom.
Between November 1986 and December 2000 approximately 180,000 cases of mad cow disease in cattle were confirmed in the UK. The highest incidence of mad cow disease in cattle was in 1992 when more than 35,000 cases were confirmed in the UK.
However, mad cow disease cases in cattle peaked in January 1993 and have been decreasing since. Currently, approximately 60 new cases are found in cattle in the United Kingdom per week.
Since 1989 when the first mad cow disease in cattle was reported outside United Kingdom, approximately 1300 cases have also been reported in native cattle in Belgium, Denmark, France, the Republic of Ireland, Liechtenstein, Luxembourg, Netherlands, Portugal and Switzerland. Germany and Spain reported their first native cases in November 2000.
Of these, all but a couple of dozen of these cases have been in four counties – France, Ireland, Portugal and Switzerland. Small numbers of cases have also been reported in Canada, Falkland Islands, Italy and Oman, but solely in animals imported from the United Kingdom.
Control measures similar to those in United Kingdom have been implemented throughout the world, so the incidence of mad cow disease in cattle is decreasing throughout Europe.
One of the reasons for concern about mad cow disease is that the disease-causing agent is unknown and new to us. One theory is that the agent is a prion, or a self-replicating protein. Another theory argues that the agent is virus-like and possesses nucleic acids which carry genetic information, but is at least 100 times smaller than any known virus.
At any rate, prions are new to us, as are really, really small viruses. The bottom line is that scientists just plain don’t know what causes mad cow disease.
Perhaps the largest concern with mad cow disease is that we don’t seem to be able to kill whatever causes it. The infectious agent, whatever it is, survives normal sterilization methods. It resists, even though its infectiveness is reduced by freezing, drying, heating, even incineration and all known chemical sterilization procedures.
This raises the question: What to do with animals confirmed to have mad cow disease? Any disposal method of mad cow disease-infected animals appears to have a risk for infection of other animals and possibly humans.
It is thought that a patient was infected with CJD from surgical instruments used on a previous patient with CJD. In this instance, the surgical instruments were first used on an infected brain, sterilized as is normal procedure and then used on a patient for a routine operation, not close to the patient’s brain. The patient was later diagnosed with CJD months later. Thus, hospitals in Europe now use only disposable surgical instruments.
So, what should dairymen and beef producers in the United States and northeastern Ohio do about mad cow disease?
Mad cow disease has never been detected in the United States, in cattle or in humans. Therefore, we need to keep it out.
First, live ruminant animals, as well as any animal products or parts where mad cow disease may exist should not be imported from Europe. Indeed, it is currently unlawful to do so.
Second, since it is thought that mad cow disease may have been spread in Europe by feeding mammal protein to ruminants, that practice (with a few exceptions) has been stopped in the United States. We need to make every effort to comply with this regulation.
Third, veterinarians dealing with animals are being trained to recognize mad cow disease, as are inspectors at meat packing plants, animal auctions and animal distribution sites. Any animals or parts suspected of having central nervous system conditions are taken from the food chain and sent to a laboratory for examination and testing for mad cow disease.
We need to support this effort instead of trying to “slip by” our downer cows. As of Aug. 20, 1999, more than 8,400 tests have been run where cattle have been suspected of mad cow disease, from cattle in the United States and Puerto Rico, with no positive cases found.
When looking for possible mad cow disease, keep in mind the clinical signs of mad cow disease are very similar to other diseases, especially other central nervous system diseases that do exist in the United States and have been here for some time.
Cattle affected by mad cow disease experience progressive degeneration of the nervous system, so affected animals may display changes in temperament, such as being “flighty” or mean, abnormal posture, lack of coordination, “splits”, not getting up, decreased milk production, or loss of weight while still on feed.
Affected cattle die and there is no treatment or vaccine to prevent the disease. The process from noticeable signs to death takes from two weeks to as long as half a year.
Hopefully if you have an animal with those symptoms you don’t have the first case of mad cow disease in the United States, but it’s still a good idea to have your veterinarian make the diagnosis.
(The author, an OSU Extension ag agent in Lorain County, is a member of OSU’s Dairy Excel team. Questions or comments can be sent in care of Farm and Dairy, P.O. Box 38, Salem, OH 44460.)