The WellnessWise Journal: reprinted with permission
Vol 2, # 7; April 14, 1996 ... Special "Mad Cow" Issue

MAD COW DISEASE: A SOBERING "WAKE UP CALL"?

Copyright 1996 by David J. DeRose, MD, MPH

"Mad Cow Disease" grabbed headlines in late March 1996 when a group of prestigious British Scientists were constrained to admit that the fatal disease could possibly be transmitted to humans. The news brought the British meat industry to a virtual standstill. English folk avoided the meat markets. The European Union and a cascade of other countries banned British beef.

Referred to as Bovine Spongiform Encephalopathy (BSE) by the medical community, the illness is aptly named. The designation makes it clear that we are talking about a brain disease (encephalopathy) that affects cows (bovine). Furthermore, the disease riddles the afflicted cow's brain with tiny holes--causing it to look like a sponge under a microscope (thus rendering the brain "spongiform"). The lay term, "mad cow disease," in addition to being much easier to pronounce, also conveys the fact that infected cows may develop mental deterioration and behavioral abnormalities.

First diagnosed in Britain in 1986, BSE has powerful emotional appeal. It is one of a group of fatal brain diseases that can be transmitted from one living creature to another. These diseases are technically called "transmissible encephalopathies." Many British consumers had apparently comforted themselves for years with the thought that it was unlikely for such a disease to spread from cows to humans. However, even before March 1996, I would guess that scientists who were aware of this fatal cattle disease would--if honest--have to admit to some level of discomfort. After all, transmissible encephalopathies affect many other creatures besides cattle. Some 16 or18 animal species have been documented to come down with diseases that resemble BSE. Many or all of those species can apparently get a BSE-like disease from eating infected cattle meat. Furthermore, cattle themselves likely contracted the disease from a different species. Most researchers believe that BSE was introduced into British cattle herds by feeding them dead sheep carcasses which were infected with a similar illness called "scrapie." (The sheep disease gets its name from the fact that afflicted sheep can become mentally unstable and literally "scrape" the wool off their hide.)

HUMANS CAN GET TRANSMISSIBLE ENCEPHALOPATHIES

However, it is not only animals that can contract transmissible encephalopathies. Humans can also get them. A disease called Creutzfeldt-Jakob disease (CJD) can be thought of as a type of fast acting Alzheimer's disease. This is an extremely rare illness that has typically occurred in older individuals. I have personally only seen one patient with this rare and fatal disease.

We know from cannibalistic tribes in New Guinea, that a disease like CJD is transmissible to humans. There, at one time, the dead were honored through ritual cannibalistic rites. Children typically ate the brains of their deceased parents during these rituals. Many of them did get a disease called "kuru" which is a transmissible spongiform encephalopathy similar (if not the same as) CJD. The disease sometimes took up to 30 years to develop. Young children who engaged in these cannibalistic practices tended to develop the illness sooner than their older siblings or peers who also consumed infected brains.

Many scientists had speculated that if sheep could transmit the disease to beef, beef could transmit the disease to humans. In fact even in the United States, a country which claims to have no evidence of BSE, there have been reports that are less than comforting. For example, an outbreak of a related illness, Transmissible Mink Encephalopathy occurred on a Wisconsin mink farm. It was discovered that the mink illness was likely related to that farmer's practice of feeding them local "downer" dairy cows. This is a designation for cows that either are so ill that they fall down and can not get up, or actually are found dead on the farm. Deemed unfit for human consumption, such cows have been used for animal feed among other things. In this case, the carcasses found their way into the minks' diets.

The mink outbreak provided another example of probable BSE infecting other species. (The link could not be made definitely since the "downer cow or cows" that were fed to the mink were not autopsied.) It also raised another concern: countries like the US who think they have nothing to worry about, may in fact have diseased animals in their herds.

Despite assurances from the USDA that BSE has not crossed the Atlantic, the mink story leaves us with an uncomfortable feeling. However, there is even more disturbing news. Laboratory research has demonstrated that different strains of prions do exist. For example, a British researcher found that when he injected the prions from an infected group of goats into mice, those mice developed an encephalopathy (brain disease) characterized by drowsiness. The prions from a different group of infected goats also caused brain disease when injected into mice; however, instead of becoming lethargic, the diseased mice turned hyperactive! The message was clear: there were apparently at least two different strains of scrapie-like illness in goats. When transmitted to another species (in this case the mice) the infected rodents came down with one or the other of these two very different looking diseases.

Such research has raised an important question. If scrapie in goats could give rise to different appearing diseases in mice, could sheep scrapie result in more than one type of cow disease? There is some suggestion that this could be the case. There may well be more than one strain or type of BSE. The different types may cause different looking diseases. Some who have been studying links between cattle and mink disease in the US, have raised the concern that BSE is present in America, but "looks different" than the British variant due to a different BSE strain. Specifically, the BSE in the US may be one cause of "downer cow" disease rather than its "mad cow" cousin in England.

FINALLY TAKING NOTICE

The biggest concern, of course, is that we are just glimpsing the tip of that proverbial iceberg. One prominent researcher is putting estimates of BSE-related CJD well into the thousands. And the problem does not appear to be confined to Britain. There are worrisome reports now from France and Italy. Still others are raising concerns that some cases of "Alzheimer's" may actually be spongiform encephalopathy. Granted, all of these conjectures may not prove true; but what if just some of them are? Even if only in part?

PRIONS: FRIGHTENING CARRIERS OF DISEASE

Prion related diseases are also extremely difficult to diagnose. There is no way to do a blood test for BSE and an infected animal does not mount any immune response to the infection. Tell-tale signs of diseases like BSE are usually only possible to diagnose at autopsy. However, not all infected animals necessarily have the characteristic sponge-like brain changes. Of particular concern, animals who carry the disease and have not yet developed signs of BSE, may not show the characteristic brain involvement.

WHAT ANIMAL PRODUCTS ARE FREE OF PRIONS?

Of even more concern is the fact that we do not know which tissues could carry the infection. Most of the focus of late has been on beef. This is warranted. Although organ tissue carries the greatest risk, animal studies do suggest that meat itself can transmit prion-related diseases. However, we cannot exclude the possibility that milk could also carry disease-inducing prions. Many may recall how some years ago assurances were given that a mother could not pass HIV to her child by nursing. Of course, we now know that HIV can be transmitted in breast milk. Granted, prion diseases are vastly different than HIV. The risk from milk (if it does exist) does appear to be much smaller than from eating beef or cattle organ tissues. Nonetheless, a British BSE expert has pointed out that there has been at least one human case that suggests passage of prions in milk. This was the case of a woman dying with CJD who demonstrated the infectious agent in her colostrum (the type of breast milk made in the initial days following delivery).

Eating the flesh of other animals (besides cows) or drinking their milk may not be safe either. These other animals may also be affected with a prion-related diseases. As we have already mentioned, sheep as well as goats can become infected with such illnesses. Even if some of these illnesses do not seem to be easily transmitted to humans (because of what is often called, "the species barrier"), the possibility exists that different strains of prions could present more danger.

OTHER CONSIDERATIONS

The current British proposal to slaughter all older cows may not go far enough. If younger cows are infected they may not yet show any signs of the disease. However, an infected cow can theoretically transmit the illness whether or not it has yet developed symptomatic disease. The widely publicized 1988 ban on feeding dead sheep parts to British cattle did not stop the epidemic. When the statistics were reviewed in a 1995 report, over half of all the British cattle that had developed BSE were born after the ban was implemented. The important message is that young cows may be infected, and may be able to transmit disease to humans.

CONCLUSIONS

If there is even a small chance of getting a severe fatal disease, some are suggesting it would be prudent to avoid all animal products. But maybe a few other questions are more important. What is the next transmissible disease in animals that will be recognized? Do I want to wait for tragedy to strike me or someone close to me--or have I already had warning enough?

APPENDIX: IS IT ALREADY TOO LATE?

Thus, even if someone was doomed to come down with a condition like CJD (because of previous exposure to prions), it may be possible to delay the onset of the disease significantly. And don't forget: a diet that moves away from animal products can also dramatically help you decrease your risk of other diseases like heart disease and cancer.

FURTHER INFORMATION

Those interested in additional information on BSE and/or other animal related diseases are encouraged to ask to be placed on the mailing list for prepublication information on Dr. Neil Nedley's book when it becomes available. In addition to the written text, an accompanying CD-ROM with color visuals suitable for public presentations will be available. Send e-mail to "docderose@aol.com" with the request "Nedley list" (leave off the quotes, of course.) You will receive further information when it becomes available.

SELECTED REFERENCES:

Send all correspondence to:

David J. DeRose, MD, MPH
Email: docderose@aol.com (preferred) 74532.622@compuserve.com