MARGARET WARNER: These are British cattle afflicted with an illness commonly known as Mad Cow Disease. Over time, the disease rots the animal's brain. Its scientific name is Bovine Spongiform Encephalopathy, or BSE for short. The disease struck the British beef and dairy industry in the late 1980's. Its incidence has now declined by 70 percent in Britain, but ever since that outbreak, the United States has banned beef imports from Britain, and Mad Cow Disease has never been detected in any herds in this country. This man, seen in a British home video, is suffering from another brain-rotting illness called Creutzfeldt-Jakob Disease. Ten cases of this disease have been diagnosed in Britain over the past two years. Just last week, a panel of British scientists that advises the government suggested a link between the two diseases. Here's what the British Health Secretary told Parliament about the scientific advisory report.
STEPHEN DORRELL, Health Secretary, Britain: (March 20) There remains no scientific proof that BSE can be transmitted to man by beef, but the committee have concluded that the most likely explanation at present is that these cases are linked to exposure to BSE before the introduction of the specified bovine offal ban in 1989.
MARGARET WARNER: 1989 is when the British government banned cattle feed fortified with animal innards. That statement by the health secretary touched off panic in Britain and triggered a ban on British beef by other countries in the European Union. But yesterday, the British government said its beef was safe and that it was not taking any new measures to control the cow disease in its own herds. Today, the U.S. Agriculture Department said it would step up inspections of U.S. cattle herds but said it had no reason to suspect the cow disease had spread here. Separately, the World Health Organization said it will sponsor a meeting of international scientists in Geneva next week to study possible links between the cow and human diseases.
For more on this story, we're joined now by Dr. Will Hueston of the U.S. Department of Agriculture, he served on the advisory committee in Britain on looking into BSE, and Dr. Laura Maneulidis, head of the neuropathology section of the Yale School of Medicine. Welcome, both of you.
DR. WILL HUESTON, U.S. Department of Agriculture: Thank you.
MARGARET WARNER: Thanks for being with us. Dr. Hueston, explain to us exactly what is Mad Cow Disease, when did it first appear?
DR. WILL HUESTON: Well, this disease, which is technically called Bovine Spongiform Encephalopathy, is a brain disease of cattle, and it is a new disease that was first identified in Great Britain in 1986. This disease over time causes the degeneration of parts of the brain of cows, so the cows start acting differently, oddly, show apprehension or aggression, or upward response to sounds and to changes in environment that beforehand were quite normal for them.
MARGARET WARNER: As we just saw in the video.
DR. WILL HUESTON: Yes.
MARGARET WARNER: Now, how common is this world wide, and where is it most common?
DR. WILL HUESTON: It's most common in Great Britain. 99.9 percent of all the cases that have ever been identified have been identified in Great Britain. They've had over 150,000 cases.
MARGARET WARNER: And what causes it?
DR. WILL HUESTON: It appears to be the result of the contamination of the animal feed that was provided to the cattle. So this animal feed contained rendered animal protein, in other words, recycled animal protein that contained the disease agent. Possibly it was the--an agent that causes a disease in sheep called Scrapey.
MARGARET WARNER: And I gather this is neither a virus nor a bacteria. What is it exactly? What's the nature of the disease?
DR. WILL HUESTON: Well, the nature of the disease is that this agent, and the agent is not completely characterized, causes a change in a normal brain protein, and that normal brain protein as it changes affects the way in which obviously the brain of the cow works, and that causes or leads to the behavior changes and also to these changes and ability to rise and some abnormal temperament.
MARGARET WARNER: And is there any way of detecting it before you see these behavioral changes in cows?
DR. WILL HUESTON: No. We have no test on the live animal. So what one does is watch the animals for changes in behavior over time, and then in Great Britain, any animal that is suspected to have this disease, BSE, is, in fact, euthanized and destroyed. And they look at the brain to confirm whether or not the--in fact, the animal was affected.
MARGARET WARNER: And I assume from that you're saying there's no cure or treatment?
DR. WILL HUESTON: No cure or treatment. Unfortunately, as a very sad consequence, it's always--once the cow becomes infected--it is a terminal disease.
MARGARET WARNER: Dr. Manuelidis, outline for us now the human disease, Creutzfeldt-Jakob Disease, in the same way. Where is it most common? When did it first appear?
DR. LAURA MANUELIDIS, Yale School of Medicine: (Stamford, CT) Well, actually, it's been known for a long time, and it's a very rare disease. It usually only affects one to two people per million world wide, except certain people are more susceptible to the disease. Clearly, the--what's happened in England has shown that this is an infectious disease. This is not just a familial disease, although some people may be more susceptible to it. It's a degenerative brain disease that has a very rapid course. The problem is it has a very long latency, very much like HIV, so it can take years to be expressed, and meanwhile, animals and people can be infected with it.
MARGARET WARNER: Has the incidence increased at all anywhere in the world?
DR. LAURA MANUELIDIS: Well, there's a focus in Slovakia that Carlton Gatiszek has written about, and that's again an infectious disease, is transmissible for cats. A number of cats have also become ill in England, about 70 as far as I know, and I think that the link between the Bovine Spongiform Encephalopathy and the new human cases is on the basis of the fact that they're very young people now being affected. Usually only people who are over the age of 50 or so get this disease. And now you have a very unusual outbreak in people who are an average age of 27 years old.
MARGARET WARNER: I want to go back to the possible link, but first just tell me, you said earlier that in the human disease there were certain parts of the population more at risk. Who is that?
DR. LAURA MANUELIDIS: Excuse me?
MARGARET WARNER: You said earlier that certain people were more at risk for getting the disease. Was this the age factor you talked about, or other things?
DR. LAURA MANUELIDIS: Well, no, I think age is part of it, but I think there are certain people that have polymorphisms in something that's called the prion protein, some of us believe that probably this is a virus. Other people believe that this is a protein infectious agent. I think the proof is not there for either theory, but we know that there are people who have some polymorphisms.
MARGARET WARNER: Meaning what?
DR. LAURA MANUELIDIS: Changes in their gene that they inherit that are more susceptible to this, so for instance, people who receive growth hormone who came down with the disease of the thousands of people who received contaminated lots of growth hormone, people who had these changes in their genome are more susceptible to the disease, although we're still seeing cases as far as 30 years after their exposure. Now, in England, in fact, most of the people have a very typical PRP profile.
MARGARET WARNER: What is a PRP profile?
DR. LAURA MANUELIDIS: That's this particular protein. They don't have an unusual mutation in this protein, so it's--they're not really people who would have a familial susceptibility.
MARGARET WARNER: I see. And that's what makes the British cases unusual, and--
DR. LAURA MANUELIDIS: The age and it's my understanding also the pathology and the clinical presentation are quite unusual. Apparently, the clinical course is unduly long, and also as far as I understand it, I haven't seen the primary data because, of course, the meeting was interrupted in Paris and their people went back to England, but apparently, there are a lot of placques in the brain. Now, these placques are very much like amyloid placques--
MARGARET WARNER: I'm sorry, your technical terminology I'm sure is leaving our viewers.
DR. LAURA MANUELIDIS: I'm sorry. There are--in Alzheimer's Disease you have these deposits of protein in the brain made by one main brain protein. Here you have another, which is made by a different brain protein.
MARGARET WARNER: Let me get Dr. Hueston back in this. Now, when the British--we just saw the British Health Secretary saying there was a possible link between these two. On what was that based? What do you think? Let me just ask Dr. Hueston, and I'll get back to you in just a minute. But what do you think is the likelihood that there is a link here?
DR. WILL HUESTON: Well, they have a Creutzfeldt-Jakob Disease Surveillance Unit in Great Britain, so they are monitoring the number of cases, and with this identification of this atypical form of CJD, they--
MARGARET WARNER: That Dr. Manuelidis--
DR. WILL HUESTON: That Dr. Manuelidis just explained, right--this atypical form, then the scientists advising the government were asked to go back and review these cases and review all the information about them to see if they could find any explanation for the atypical form. Unfortunately, unfortunately, they could find no identification with human growth hormone or any of the other known risk factors for CJD. Consequently, they came to government and said this is a new, this is a group of cases that shows some atypical clinical signs, some atypical brain abnormalities, and in the absence of any other explanation, we must evaluate whether or not there's a connection with this new cattle disease.
MARGARET WARNER: Dr. Manuelidis, what is your--your view of the likelihood of a link?
DR. LAURA MANUELIDIS: I think most of us in this field, regardless of our views about the cause, believe that there's a very strong link and a strong likelihood that these cases were caused by an oral infection in the case of the young teenagers and maybe more direct infection in the case of the Avitar workers with infected bovine products.
MARGARET WARNER: From the period of time before 1989--
DR. LAURA MANUELIDIS: Right.
MARGARET WARNER: --when they changed the feed.
DR. LAURA MANUELIDIS: I should point out to you that the recent data that I've seen, BSE is not entirely eradicated, and some cases of BSE have slipped through.
MARGARET WARNER: Now--
DR. LAURA MANUELIDIS: I might mention one other thing. Dr. Hueston mentioned that when you see the clinical disease, in fact, that's fairly latent a disease, and you have the infection long before you see the clinical disease. So it's very difficult to recognize.
MARGARET WARNER: Now, Dr. Hueston, your--the USDA today announced they were stepping up testing here. What does that involve?
DR. WILL HUESTON: Essentially, it means revisiting our whole program as it relates to this disease in cattle. Now, I hope that your viewers are comforted by the fact that early when this disease was diagnosed or first diagnosed in Great Britain, the U.S. Department of Agriculture and the Centers for Disease Control, and the National Institute of Health, all working together, had been involved in looking at this disease since right after it was first identified in Great Britain. So we've had measures in place to prevent the entry of British cattle into the United States and to prevent any introduction of the agent through meat or products from Great Britain to the U.S.. And now we're re-looking at those. On the basis of this new evidence we're pulling together, again, researchers, industry scientists. We're pulling together CDC and NIH to make sure that we haven't missed something.
MARGARET WARNER: Dr. Manuelidis, briefly before we go, do you think there's any reason for Americans to change their eating patterns in any way?
DR. LAURA MANUELIDIS: Not at the present time, but I think what Dr. Hueston mentions about increased surveillance would be of great interest. I hope not.
MARGARET WARNER: Dr. Hueston, what about--anything Americans should--
DR. WILL HUESTON: Well, I think Americans must recognize, we all must recognize that in choosing our diet that every dietary component has some risk, and we need to balance that risk. I've looked at all the data, myself. I'd make a personal decision. I was in Great Britain. As you know, I just returned last night. I had beef, British beef on the way home. I don't have any concerns about it for myself.
MARGARET WARNER: All right. Thank you both. We'll have to leave it there. Thanks.