Focus 580; Mad Cow Disease

Last week a week ago today in fact the U.S. government announced that a cow in Washington state had tested positive for mad cow disease. It is the first time the disease has been reported in this country and you'll probably recall that back in the mid 1990s there was a very serious outbreak of mad cow disease in England. It also spread to Europe and to Asia as a result. Millions of cows were destroyed scientists also believe that a related disease a human form of this disease killed more than 140 people mostly in Britain who ate meat products from infected animals so there certainly is a concern about the possibility of mad cow here in the United States. What it means for human health and what it means for the livestock industry. We thought this would be a good opportunity to talk a little bit about mad cow disease and to review what it is what causes it how it spread and what it is that we're doing to try to control the spread of the disease. And for that we have this morning with us on the program. Philip yam He's a writer for Scientific American.

He's been working for the magazine since 1989 Currently he's the magazine's news editor. He's the author of a recently published book that we discussed on this program back in June. The title is the pathological protein mad cow chronic wasting and other deadly prion diseases. This book is published by Copernicus. It came out in June and it's an account of how it is that scientists gradually put together the pieces of this puzzle to understand what mad cow disease was and what caused it and how it was spread. So if you're interested in reading that story it is a quite interesting story. You can head down to the bookstore and look for the book. And of course as we talk here this morning questions are welcome. If you were here in Champaign-Urbana where we are 3 3 3 9 4 5 5. We also do have a toll free line and that means if you're listening around Illinois and Indiana over the air or you're listening on the internet as long as you're in the United States you may use that number and that is 800 to 2

2 9 4 5 5 so again 3 3 3 WRAL here in Champaign Urbana and toll free 800 to 2 2 9 4 5 5. Mr. Yam Hello. Hi. Thanks very much for talking with us again we certainly appreciate it. Yeah Hi David Thanks for having me. Well just again what I thought we should do is review some of the basics about mad cow disease in the other related kind of diseases and maybe a point to start is to talk about what it is that causes these diseases. This was one of the things that we learned eventually and that it was something of a mystery. And it's quite interesting from a scientific perspective because this is an infectious disease but the agent that causes the disease it's not a bacteria it's not a virus. It's something else. Right. It's not a fungus or mold. It's actually a protein protein that is called thought to be called is now called actually a

prion for pro tenacious infectious particle. We now know that basically the prion is exist naturally and all animals. What happens is the way it causes disease is that it's somehow mis folds into a different pathogenic state. And in this pathogenic stage can convert other normal prion proteins to a dog. It's malformed shape and therefore go on to cause disease. And there are a number of these diseases that occur in particular animals so we know that it can spread from one animal of the same species but of course the other thing that we have learned is that it can go from one species to another and produce similar kinds of symptoms and and the reason that these are called spongiform diseases. It is what after the animal has died if you take a look at the brain of the animal or it can be also a person that you see that it has a kind of a spongy appearance. Right it really the agent seems to pepper the brain full of holes and that's why you see a lot of neurological symptoms and mad cows they just kind of stagger around the charge

of their handlers. And you're right this is a disease that's been known for a while in animals and actually the first animal was in sheep and they call the disease back in the 17th century scrape be because the animal would basically scrape its fleece off it would just basically act strangely. And the UK you merge that mad cow disease is thought to have occurred because they contaminated sheep scraped sheep or were ground up and made it to animal feed and given to the cows which eventually ate you know a scraping victim material and develop their own. Sickness and so the concern here obviously is that that can happen. Apparently we also believe that a human form of this disease that's called the variant Creutzfeldt-Jakob disease variant CJD can also be caused when human beings eat some meat products and then we want to duck very in some detail about what would it be is that's really the big problem but we think that those people in most of

them in Britain or a Gallup variant CJD we think that that was the result of eating some meat products from animals that were infected and it was probably that it happened in this way it was back at the point where there was still animal products in the feed. So Rice infected sheep were fed to the cows the cows got infected and then people some of the people who ate some of that then they got it figure that's right. And in that that the peak of the BSE it was the tip of the official term for mad cow disease as bovine spongiform encephalopathy or BSE and the BSE hit its peak in the U.K. did in the early 90s 92 93 percent are tapering off. And then the first cases were occurred in young people around the mid 90s. And because the incubation period is believed to be up to upwards about 10 years they probably ate the infected me probably no early 80s. And that's where the first cases started dying in 95'96. That in 96

is an important year and the British government because that's when they realized hey madhouse might actually be able to jump to humans even though we've been reassuring the public that it can't. You know one of the things that perhaps people have seen if if they read some of the stories is that the the disease causing agent the prion seems to be in the animal seems to be in the tissues of the nervous system so right now you're thinking about the brain the spinal cord. Things like that right. And that it should not be in the muscle that is mostly what we eat so that I guess the question is if if you're having a steak from an infected cow what are the chances that you would then encounter the prion and possibly get say the chances are going to be extremely low and the reason that a lot of scientists say this is because of experiments in the U.K. in which they tested the various parts of the cow to see what was really infectious what was prion infectious it bits of the spinal columns various

parts of the various organs of various muscle meats and injected into a test animal to see if a test animal comes out with a disease churn up the brain in the nervous system because of these uniformly the muscle meat never did. So that was the conclusion that there's there aren't any infectious plans in the skeletal muscle meat the kinds of things that we usually eat. What you'll hear now though is that there's been last year there was a couple years ago. There was a study coming out of University of California San Francisco that found pretty infectious browns and skeletal muscle of mice mice were infected and surprisingly it showed up in the muscles there. Now the big jump to go from mice to cattle as it is to go from mice that humans I mean a lot of drugs work well in mice and don't work at all in humans. But it's something worth looking at again to see if you know whether or not cows might actually deposit infectious Prince I'm awful at the moment experiments they know but right experience suggest that you know it could be possible in mammals. But you know I

feel more confident with the with the inoculation experiments in which the cow muscle meat was injected in mice and did not show disease from one of the stories that I have read. The numbers of people that are believed to have acquired variant CJD from eating infected meat products most of them in Britain and we're talking about maybe about 140. That's right. People in round figures now when when the when there was the big outbreak of BSE in Britain and then the connection was made between variant CJD and eating meat. The big question a lot of people had was well what are we going to see in terms of Variant CJD as a result and that was something that was very difficult to say. Now I know this many years later if we've only seen 140 cases. One might think well maybe it's not going to be a huge problem on the other hand when you're looking at the long incubation period you still have to say well we're not really sure what's know the thinking. If you know ultimately the impact right

human health of that least that particular outbreak going to be right. As time goes on it's good news because that means fewer people are probably likely ever to come down with the disease. So I mean the initial estimates especially early on in the mid 90s were that hundreds of hundreds of thousands of the millions of Britons would come down with the disease. And now that number has not been increasing in fact maybe tapering off or flattening out at least that's good news suggesting that at least for some kinds of people a certain population of people that. The activity was relatively low. Part of it is the fact that they estimate 200000 cattle were found about 180000 June 2000 cattle were found to be infected with the BSE mathematical models suggested 1.9 million cattle probably were infected and escape detection. So that's actually kind of good news because that meant there was a lot of infected mean out there. And we've not we're not seeing a whole huge increase in infection rates. So as time goes on that's good news. But you can never really be sure

about when the disease actually manifest themselves and in the case you could look at it as cover which is a disease of a tribe in in New Guinea back in 100 40s and 50s especially their side is being devastated by this basically a version of Mad Cow disease in humans. And that was because they practiced cannibalism where they would eat their own dead as means they get strength from them. And they suffered tremendously and is only when they finally banned the practice of cannibalism in late 50s that the. Epidemic started tapering off but in fact even more than 40 years after that has stopped people are still dying of croup. That's the name of the disease. And that's amazing I mean at 40 years these people probably just were just participating only a few of these cannibalistic season as children and now and they're elderly now and they're dying from it. So that's kind of amazing that this incubation period can last more than

four years. I have some callers here and I want to get to them in a second we just asked one of the question at this point and we'll see what's on the minds of the callers here now. We have had identified in the United States one animal rights tested positive for BSE and it apparently was a dairy cow that was thought to come from Canada. The Canadians are kind of saying well we're not really so sure about that. Or was it was one cow that it was at the end of the cow's productive life as a dairy cow so it was it was sent to slaughter and it was determined that it tested positive for BSE. One has to imagine that there's got to be if there was this one cow there's got to be more than that. I think that's a good assumption I mean generally when countries have found one they found more than one. If I don't many others but there are few countries in Europe that have just found one. And Austria and Israel are two examples of countries that have just found one. And Oscar in particular was instructive because it was categorized in the same risk category as the United States. They tested hundreds of thousands and we found one so far.

And so it's possible that we might only see one but I think more likely is that if the cow was contaminated by feed a lot of other cows shared in that feed and that means that all the cows are probably infected if there or if we might never find them because they may have already been slaughtered. But yeah likely it is the betting line I would say is that you have probably other cows out there you know how many is not known. You know one of the recent developments in the story was that apparently now they have decided that the cow is a little older than they had first thought and that they believe that the cow would have been around before the ban on feeding animal parts to other animals was put into place that was as as as we have explained what happened was they think in Britain that the cows got it from eating parts of infected sheep and then the people got it from eating parts of infected cows and so at that point they said OK we're we're not going to do. Do that any more. This animal was old enough so that it would have been around before the

ban came into effect and that is the thinking is that that's probably how the animal became infected. Right I think it's really critically ages really credible and initial reports that it was only four to four and a half years was really kind of scary because that meant our feed ban rules were not being adequately a force not six six six and a half years old or so it was before the feed ban was implemented. So you can kind of yeah wave your hands and say well this before we really implement to implement the strict rules the basic rule to keep it from amplifying the prevent from amplifying is that you don't feed the cows other cows I mean that was what really amplified the situation in Britain. You know the after cows died they sometimes converted them like they bring a spinal column in particular to other cattle feed someone else would eat it. So that's what helped really kind of blow up the epidemic. So that is you can't do that now in the U.S. in Canada in August 1997. The ban the feeding of all mammalian protein to cows and this

is this is a disease that affects ruminant animals so I guess again it's my understanding that there is no mad chicken disease so that wouldn't be an issue. And this also there's this does not if there's no disease that affects swine like this you can experimentally give the do give pigs a disease if you inject a bit of brain matter into their own brains if you inject an effective sample insulin brains in feeding experiments that they did in the U.K. in which they said. BSE infected material to the pigs the pigs remained healthy. So maybe that's why that's the justification for allowing pigs to still consume feed made from cows chickens. No one has ever seen the same thing with chickens and with ever seen kind of a spongiform encephalopathy in chickens given through the feed. Oh there are holes in gaps for instance you can feed chicken litter to cows chicken later stuff that falls to the floor feathers of feces and even

the feed that you give. So in principle you might be able to get the cow ruminant right feed your men for the chickens back to the. It's not believed to be a widespread practice that is thought to be only on the few small farms if at all but nobody knows the extent of it but the thing is it's not illegal. We're talking this morning with Philip yam. He is the news editor for Scientific American magazine and has been working for the magazine for a number of years. If you're interested in reading on this subject he wrote a very interesting book that's titled The pathological protein which was about how it is that scientists figured out what caused a mad cow and how it was transmitted and the link to human health and so forth that book came out in June published by Copernicus so you can seek that out questions here welcome We have several people ready to go 3 3 3 9 4 5 5 here in Champaign Urbana also toll free 800. 2 2 2 9 4 5 5. First caller is in Champaign and line 1.

Well well Hi I'd like to recommend some more reading for people. I read this out of everything you know is wrong with this information guide secrets and lies. It's called bioterrorism and the perfect pathogen bovine bioterrorism the perfect by Christian or cursed primer. He raises a few interesting points like for one. There is a hunter and you believe Doug McEwen that was had. I guess you'd call it very in the J.V. from deer and stuff that he hunted and he donated blood and apparently he was allowed to like be processed in and go to 46 different countries or something like that. And as it is now you're saying well it sounds like you're saying there's a low risk for. Blood transmission but people from who spent three months in Great Britain are not allowed to donate blood to the Red Cross and also one other thing that

I'd like to bring up. I'll just read this from the book because it's brief. In 1905 Dr. Richard mark a TSC researcher at the University of Wisconsin investigating a mysterious outbreak of transmission transmissible in conceptual up the TMB in the state found that the mainstay consisted almost exclusively of downer cows animals too sick to stand in March 1994. Maher showed that when the brains of the infected cattle were fed to a healthy mink they developed TMB healthy cattle inoculated with the tissue obtained from the team e infected mink. Do we developed BSE. I just like to get your reaction to those two right things. What you brought up the mink part because I've been trying to get answers from the USDA about this and the issue is that is there an American version of Mad Cow Disease native strain that exists here and has existed here for decades that we haven't really been able to find yet. And one of the thinking and a lot comes from Dr. Richard Marshall's work with Mick is that

yes there is such a thing here in the U.S. to produce a set of symptoms different from what you see in the UK. Now what's interesting about the cattle cow they found was that it was a downer cow. And the reason the main problems they could find with with it was that it had hemorrhaging in the public and now and other problems really associated with pregnancy. There was no obvious signs of the typical BSE symptoms of starting around and acting aggressively. So whether or not this represents a new strain of disease it's not or an American strain that is not really known what they would have to do is take a sample of the cow's brain and then run an inoculation experiment inject it into a rodent and compare that with the BSE material from England inoculate all Center and see how the symptoms emerge that would if they're the same and then you can probably assume that it came from feed contaminated feed from the U.K. somehow if they're different that sort of suggest different. Different game here. Another possibility which you raise also of the chronic wasting disease in Utah is. Could you

also be the source of an American strain of these of the person who died in Utah did not die a very cold so I could see he died of course well Jochum disease they assume it sporadically tried to find a connection with deer did not find it. But no one's ever no one yet has ruled out whether or not chronic ways to prevent these of deer and elk could jump to humans. Now there is a worry that it could jump to cows and they're doing experiments right now to determine that so far the feeding feeding and experiments have not shown that cows can get sick from eating meat. But those experiences still ongoing. They can get it when you know there are inoculated with the DVD into the brain. So in principle Yeah they can get it. So whether or not this cow was exposed in some way to the deer is not known at this point but it was in Alberta Canada which is a. Robinson which si deputy has been spotted in Farmville. So it's they still have to do that. Those kinds of experiments I'd be really interested to see what kind of results they get out of

that. The other serious thinking along those lines is that cattle get mad cow disease spontaneously much as humans get caught for it sold Yakob disease spontaneously and one out of a million cases. So that's certainly possible but if that's the case if cows do get spontaneously that means they've been getting it for decades and well hasn't pose much of a problem in the past then you might draw a conclusion that it doesn't pose a problem in the future. I wouldn't take that bet myself but that's one of thinking about it but you're certainly right that there is a hint that an American strain exists but so far it's very difficult to prove. I'd just like to ask about the hunter was only 30 years old and what I understand usually when people get random cases of the very old people and often right time or something like that are absolutely other cases of people that young.

Yes they have been and that's why the CDC or every appointment book that several young people have now been found to have died from quote still Jochum disease you know in a period from like the late 90s on which is really unusual. And the CDC has looked into these. He says but couldn't prove a link between chronic wasting disease deer or even beef with this disease as far as I can tell it looks like sporadic CJD. Yeah but young people are getting CJD is unusual so when you find a cluster or is it a group in time or space. That's something worth looking and into so the CDC does check whenever someone under 30 dies of disease. But yeah at this point it's hard to join a firm inclusions. OK. OK thank you all thanks for the call. Just again to be real clear. We talk about the fact that there are a number of these spongiform diseases you see them in different animals and that we've to stablish the fact that it can go from one species to another. There is this version called chronic wasting disease that you see in wild deer and elk that's. But it is

not the case I just want to make sure that has there have there been any warnings to hunters about whether or not it's OK to eat wild deer. Yes there have been warnings about how to avoid the brain and the and the spinal column and to make sure you decontaminate clean off your plate really well not use the same plate used to strip the carcass as you would to cut you know the meat on the kitchen table. OK as otherwise it's the same thing as applies to collars the right thought is if you. If you're eating the muscle meat that that should be that OK right. That's the thinking right now but again chronic wasting disease fairly. It's become an epidemic proportion in some areas of the country only fairly recently. So usually it's a lot of the tests and data are ongoing and we really don't know what incubation period would be in humans at this point. OK urban The next line number two. Hello hello. You have just one point for you that said that it was a disease of animals and there are at least two species in this

country that are not vine and the mink for instance the first occurrence of the encephalitis was I believe in the 70s. And in that case it had become epidemic because they were really using mink carcasses. Which would indicate that there is some Mormon of this disease that probably occurred spontaneously in a mink population doesn't it. Well no one's really sure about how the brain got to first of all the disease occurs in different species or talk about mad cow disease as only occurring for bovines are ruminants that right special disease right. But there is I mean absolutely true in the 40s and 50s and on these mink Farms was it that early. OK yeah when it dates back to about four thousand fifty one farmer and the mink were basically fed the scraps from. From there some the slaughterhouse so it was also there was any carcasses that could have been so I mean that may have well been amplified sanitation but I mean they were fed a lot of the high risk material to us

and we had scraping in the country as well so that's also a possibility. Well supposedly that didn't appear until the 50s but I don't really believe that yeah yeah it's hard to say when. Yeah I mean we have seen scrapings I think even a little bit before them but the mind largely not I was active in the breeding of pure bred sheep that I'm very well acquainted with the situation there. But the the main the control of the of the epidemic was from stopping the practice of reusing them in carcasses. OK that's a long time so that's good. But I do have two questions. I'd like some of your best opinion on the great bee appears to be mildly contagious. Right. And it obviously is not due in the 17th century to the reviews right. RUFF You know there must be some means of communication right. This is also true of deer.

Absolutely. Other animals seem to spread it by other means. I mean deer especially seem to spread it by contact with each other possibly through the urine through the mucus membranes they nuzzle up with each other a lot. So nobody really says so yeah it does spread between individuals and cows. They don't seem to act the same way and nobody's really sure why. But again the presumed factor is primarily feed and when in the end we have the best luxury of time to see how the UK handled their epidemic and when they finally banned the feeding of cows the cows the epidemic clearly start shifting So clearly the feed was a major factor now. Not to say that there are other possible factors and one was always that the possibility of maternal transfer that cats could get it from her mother. No one is able to disprove that but at most based on the cystic only occurs at most a 10 percent if at all.

We had thought that was the case with great be in range if there's another agency. There are of course the one time the bovine and the R in the sense carnivorous is in the consumption of the after birth right in that that would happen even with year b a means of communication right. The idea is that when they give birth they can also drop the placenta on the on the ground and contaminate the ground that prion can remain infectious for years on the ground. One other question does anyone know about the let's see it's CJD isn't it incumbent that prion disease or do we just not know what present it is a prion disease when you look at their genetics and you do get CJD can also be a hereditary disease and it's partly due to mutant PR people BRP gene protein gene difficult. We're not trying to

avoid the acronyms that are common in the whole field. But yeah you can take someone who gets sporadic CJD you take a brain sample you can infect another animal with it and then it's free and I suppose the manufacturing practices in the modern day have much to do with the possibility of it being the the bovine variety being spread where one animal intermixed with hundreds perhaps right. Others. Right. Yeah the industrialization of Agriculture and the changes really have made things unusual. I mean agriculture is really a natural for the animals and completely. And some of the practices you know I guess lead to predictable events. One reason we may not see it developing actually as often as cattle as we might in fact when I was a. Boy

we had cows that were 15 16 years old and still fully productive. Rarely does a dairy cow survive. You know I'm right here six years today and that doesn't give enough time for the state to help right. Well I'm an optimist enough of your time. Well thanks for the call. Just to follow up on one thing real quick the caller said I think that there are some people that are concerned that there are practices now where they're trying to get every tiny bit of animal protein off the carcass of the cow and that there's some possibility that in the process some of that nervous system tissue that had that may have prion in it may indeed get end up getting mixed up with the meat. Now you're not going to get that on your steak right perhaps if. If you buy ground beef for example something like that some. Some kind of product where meat is ground up and mixed together than that might be an issue. Is anybody saying well maybe for that reason that there's a certain point at which we ought to say we'll stop whatever's on the

carcass can stay there or at least it's not going to be it's not going to end up in the food chain then. And in something that's for human consumption right. The the FDA and USDA have been kind of to looking at that for a long time and I know that they haven't really decided whether or not to ban the use of brain and spinal material in for instance feed. But I would assume in this case we definitely push the government to to bad that I mean it's certainly possible that when you use these advanced meat recovery systems you know you base you high pressure jets to to blast the meat off the remains of the cow. And yeah you can get a spinal column material on brain internally to specially prepared processed meats like sausages hot dogs and hamburgers. So I mean even and if they're even considering banning certain kinds of stunning methods of cows and normally a cow is killed with with a captive bolt or stun the captive balls of the bolt is fired to knock it knock it out. But what's

legal still is the use of injected air where. It's been an intense pulse of air is used to scramble the brains. That's also been shown to be able to push the brain down the spinal column and into the bloodstream and they've actually found it's a brain unlike kidneys. Well let's go on we have a number of other callers will try to get as many as we can next as in Urbana this is lie number three. Well yes I would. And PBS and they had a segment on the and they had a Canadian official saying that certain parts of the ball and then that carry the prion. I was wondering if you knew anything about that. It sounded like it was an early warning or that you find it developing in the brain. Right. What's really unusual. The portion you're talking about called the distilling of a part of the small intestine and what's really weird about about this is that it shows up in very young cast and then disappears. So nobody really knows why. So basically they said well we should span it because even though that part of the spinal

column a nervous system is generally thought. Seems infected at least early on in the early stages and then goes away and nobody knows why. OK do you know what percentage of profit we're talking about for the whole industry comes from the awful I really don't know the details of the rendering process is very secretive. They don't really allow reporters to see the kind of the inside so they're very hard to get in there but I really don't know the numbers for that. OK one last thing. Do you know how much of that feed in the are in the. Some have you know remained animal and thing up and thank you. I would assume most pet feed is made of kind of the leftover animal remains and stuff we wouldn't need and that in fact is what how the UK actually first saw evidence that mad cows could. Disease could jump to other species that actually occurred in cats. First cat actually came down with it in 1990. Critter shoots up for a Siamese cat named Max and they call the cat

Mad Max and it was a pretty huge uproar and but the government at the time denied that it was any connection but later on they realized it. The cats were getting it from eating their pet food derived from cattle parts and several dozen cats actually died that way. Let's go to Champagne County the next color line one hello. Hi. The UK seems to be very serious about prion transfer and infectious realty of blood I mean the earlier caller talked about right over here over there but apparently they don't use their own blood currently for sure and they buy it all from another country at this point because. Yeah I'm glad you brought up the blood issue again. Yeah. For in the U.K. anyone born after 1906 gets blood from overseas. Anyone you know if you're born before then you're already exposed presumably. It doesn't really matter. The concern is that yeah if you're if you're actually getting pretty infectious prion by eating it it's got to get the

bloodstream at one point in your life so even if you can't even if you can't detect it at this point. So yeah it was a prudent thing to do to avoid cutting off the blood supply for the people born after 96 and if you lived in the U.K. in Europe for a certain amount of time and you can't donate blood in United States because of fears of mad cow disease and they said that it's not the cause. What if it's three months really because that's the time that the amount of blood loss is what the Red Cross thinks they can make up in donor drive here. This really is kind of in that sense a kind of arbitrary. If they could they'd been the entire anyone who's been to the U.K. for any any length of time that that would be kind of super safe way of doing it. But so far there hasn't been any evidence that blood does transmit the disease. So if I would and I understand the Red Cross and an American blood centers are in some periods of chronic blood shortages and really can't have people dying just because of people not donating blood on fears of mad cow disease for this I don't think it's absolutely

absolutely true that there's no evidence of transmission. Yeah that's true other than cheap the cheap Where are you able to transmit sheep disease through sheeps with blood so the freon is concentrated in the in the nervous system spinal cord and all that I mean is are improperly folded natural protein I understand and it sort of has. It has a bit of a catalytic effect right it turns right so the idea is that if you can fix this prince from cows It certainly gets into your bloodstream then it piles up into the nervous system where those cow proteins start making your own normal print proteins mis fold and then creates a kind of Ice 9 effect where the rest of your prion protein start mouth mist folding and coming and stronger brain cells what's called widely a ban on feeding the ruminants and is not supervised at all you mention that maybe small companies might. Smaller markets might but it keeps calling it a band it's just basically. Yeah absolutely there was basically a labeling plan.

Yeah absolutely I mean early on the compliance with those rules were pretty weak only 20 to 25 percent were not in compliance with the FDA rules and at the time the FDA really didn't have much power to force compliance and basing with and warning letters and then not follow up sometimes. But in the latest numbers at the U.S. The USDA or the FDA presented they found compliance at least for the surveyed plants to be pretty high. Only two out of what here. One thousand eight hundred twenty six surveyed firms are out of compliance and that's pretty good. So so far at least what the FDA looks at their particular firms they are following the rules so that's good news. But we'll see how well they can get to 100 percent. I'm not sure how reliable any of that is because. Obviously they talk about how their testing program and they test less than 100 percent. Well see that that's another issue and that's true. The USDA did not test sufficient numbers especially throughout the 1990s. They tested only 700 downer cattle which are the cattle most likely to have BSE.

And my own back of the envelope calculations like figure that you must make should we test a few thousand and they only reach the number in the past couple of years. Twenty nearly 20000 last year and over a little bit over 20000 this year. That's at a level where you can actually really detect BSE in really one out of a million cases and I think the fact that they did find this one cow shows that yet we've finally gotten to a sufficient level of testing at least us to find a disease early on certainly testing just a few hundred downer cows was just not not. You're not going to find it. Well speaking of testing though I mean the the UK Europe and Japan is almost 100 percent testing Europe test cattle older cattle over 30 months because that's how I sense that the rapid tests that they use. That's basically how they can't detect anything below. Anything in younger catalysts presumably a young cow is incubating the disease but at such a level that the test can't pick it up so it's kind of pointless.

Which brings up this other test that I've just heard about. Do you know this test that was actually developed in Iowa. Mary-Jo sure Mira Nair and Alpert in there with the comb hundreds Tillich and interaction chromatography test for very low levels of prion that apparently this woman investigator feels that she was ostracized for even suggesting that the USDA investigated and it's been patented by the USDA but it's been turned over to a private firm. Right. Weren't doing much with it here. But it's but it's being tested quite seriously in the U.K. And yeah as soon as they look at that maybe try to develop a front but yes. One of the great needs is for a live test or a test that can detect very low levels of the disease and so far I mean calls right now to use existing tests for all flooded animals is really kind of pointless because most of our cows are slaughtered and they're not even 18 months yet wait for any of these tests and pick up a disease. So you just developing all these negative results and maybe get a false sense of security. But in Europe they they only look at animals over 30 months which is more where

the U.S. can reliably pick up an infection. We have less than 10 minutes left here and I have a number of other callers and I hope the caller forgive me for wanting to go on I also want to reintroduce the guest. We're talking with Philip yam he's been writing and editing for Scientific American magazine since 1989 he's now the magazine's news editor. He's authored a book that explores mad cow disease and how it is we came to learn what it is and how it works. His book is titled The pathological proteins published by Copernicus books and came out in June. If you want to look at that you can head out to the bookstore or the library. Questions are welcome to hear on the show. One quick question. The reason that this cow particular cow was suspected was when it arrived to the slaughterhouse it was what they call a downer cow which means they would meant it couldn't walk or was right problem walking which gives you some kind of idea there's something wrong with the animal. So what they did was. They took the brain in the nervous system tissue and they took that separated out and took samples and then processed the meat and I guess there are some people who would

say that we ought to think differently about these downer animals that may be if we're really think that there's some possibility that and that that animal has BSE then maybe the downer cows should just be should just be destroyed or should be separated and that shouldn't go any further than there. That's true I mean part of it is a problem with the definition of downer cattle is that it refers to any kind of cattle that can't walk. So if you have a broken leg but it's fine otherwise it's classified as a downer cattle even though it means probably just fine. The real question is why is the USA still uses the kind of old style testing which takes a couple several days to come up with a result when the rapid tests have been shown to be pretty reliable these were developed more recently and they could have found out that this cow was sick in a matter of hours rather than matter of days. But you say you still don't think that it would be necessary to test every cow. I think not every cow calico Slaughter I would think it's worth considering cows that are over 30 months OK are certainly for downer cows I think rapid the rapid test

use in Europe which don't cost that much should be used on those cows. Bloomington Indiana next line. For a couple more questions about prions prion Why are pretty arms called particles to the molecules. You can call them molecules I mean it's basically a chain of about 20 50 amino acids. So yeah it's a molecule it's a protein expressed. You have a gene for that makes a protein. So yeah you can make all the molecules you want. We're not as a prion have any of the characteristics of an enzyme like like a rogue in Zion yet in some ways you know enzymes are also proteins but it doesn't really I guess you can say it has an enzymatic function in that it can for its other catalyzes some sort of reaction but not enzymes the way you normally think about enzymes which sort of boost the reaction speeds of chemical reactions. But yeah you can consider it sort of has certain kinds of and's matter. Properties were isn't given that a legitimate function of an enzyme to make

certain that a protein molecule is folding the right way and if a prior is causing the protein molecule to misquote people the wrong way to assume the correct shape is in my correct Well there are lots of other enzymes in your body that is supposed to ensure the proper folding of proteins. And if it's not proper it destroys them. You're totally making this all the proteins all the time. The question is why does the prion protein mis fold and persist in can persist in part of the theories that are garbage disposal systems start breaking down and can't keep up with the amount of prion protein misfiled appear in protein that is being made so that while normally our bodies can actually disassemble a missile that infectious preying on people who get sick from it maybe not might not be able to keep up with the rate of conversion so that the proofreading system that think it is a mistake being made here let's correct it. It might be something. The proofreading system I mean the Army on itself is not a proofreader it is it really just seeks to seek to create more of itself so its up to

your others body's defense to fight it off when they are being misquoted protein molecules. Are they the things that cause the spongiform texture of the it's it's it's part of the whole breakdown process in which the for some reason the cells know which was what the print pretty normally does but presumably it builds up in the cells. Can't get just fast fast enough in the cell just explodes or dies and spreads out other prion of infectious Brown molecules and that's sort of why that's one working theory about why you see the holes in the foot. But I should. Say that the Pre-OT there is still a theory. There's other factors that must be involved to make the prion go rogue. It can't be. It's not doing it by itself it's enough experimental evidence that it needs some sort of help. Did you say that the prion pigs over the genetics of the cell and reproduces itself. It's like a virus then it acts like a virus and for years it was thought to be a slow virus but what it does

it takes over. Then take over the function of the genes in the gene production but just takes over the changes of the protein that are already being expressed by the cells so your cells expressing normal prion proteins of the rogue prion will graviton and make it malformed. Well how does the prion itself multiply if it does it basically grabs on to normal prion that converts it to its rogue form so then he had two rogues go on to can recruit other normal prion proteins and so on and so forth. Wow interesting think thank you very much your very much will try to get one caller real quick here lying to you in Champaign. Hello I grew up on a dairy farm and every time I see that one clip that any news agency use of a calf an infected calf you know with the stilted walking with the legs splayed out from right. Right I say I have seen that before I start where we had calves that did that in this would have been in the mid to late 50s right. Will they. A lot of things that can cause spongiform change in an animal. They can

create holes in their brains. I mean toxic poisoning can do it. So in other kinds of inflammation can also produce those changes. So the key question is whether or not it has. You can find the infectious prion proteins which we have tests for you know back then. It's certainly possible that it had some sort of mad cow disease back that if you scratch a theory that we had an American strain that's been an Demick and we've been living with it without knowing about it. But it's really there are other conditions that can cause an animal to do that. Well I remember it did not spread to the herd in the cancer but yeah maybe one to three of them in my memories that are fuzzy so. Yeah that's the good thing is that mad cow disease not does not seem to spread from individual to individual but only by feet so if the calf were not there we're probably not really infectious to it heard me. It would only be fixed if it were converted to animal feed. Another quick question Is there any relationship between crates Jakob's and timers. People have looked at that and the answer is No. Alzheimer's is

just the protein that goes haywire in Alzheimers is different tends to be a beta amyloid protein and on top proteins Crisfield Jochum diseases specifically are connected to prion proteins. So they're different. They're going to get them go haywire and all timers have not been shown to be infectious transmissible experiment animals. Right. Thank. Well thank you very much well there we must leave it to one more time I want to mention that if you're interested in reading more about mad cow disease and what we have learned about it and how you can look for the book that we have mentioned the written by our guest site of the pathological protein mad cow chronic wasting and other deadly prion diseases published by Copernicus books was published in June by our guest Philip yam. He's news editor for Scientific American magazine and Mr. Yan thanks very much for being with us we really appreciate it. Thanks but David also of a website for the book w w w dot the pathological protein dotcom case and with interest and for more information.

All right very good. We appreciate it. All right thank you.