Prions and some horrible diseases
Twenty-one years ago, the world first learned of Mad Cow disease — an always fatal neurodegenerative disease of cattle.
To prevent its spread, almost 200,000 cattle were killed in Britain, but the fear was not so much about what would happen to the poor cattle. It was over what people could get from eating their beef — the human version of mad cow disease. Several hundred people did die and a few still die. These were infected back in the day.
Human mad cow disease, technically named “variant Creutzfeldt-Jakob Disease” (vCJD) is one of a number of transmissible spongiform encephalopathies, all of them nasty maladies.
The tongue twisting name means “an infectious disease that turns the brain into something like a sponge” — riddled with holes — not the kind of brain you’d like to have.
The official conclusion was the cattle probably got the disease from being fed offal — rendered protein products from other ruminant animals. That includes sheep, goats, bison, elk, deer, and cattle themselves. Some terrible disease agent was hidden in the offal. Feeding cows this stuff was almost like turning cattle into carnivores or even into cow cannibals. It just wasn’t a natural kind of feed.
Stepping back in time, it is hardly surprising that the very first transmissible spongiform encephalopathy discovered wasn’t mad cow disease. It was a disease that struck some real cannibals.
The Fore people of Papua New Guinea had developed a funeral ritual that involved cannibalism. The cannibalism wasn’t what many might expect — not hunting and killing people as food. Instead it was eating of tribal members based on love and respect of the deceased.
As a gesture that their loved ones were too important to be buried and eaten by worms and maggots, Fore women (primarily) cooked the corpses and then ate them beginning with the brain (which turned out to be the most infectious part of deceased). Before the 20th century this ritual was apparently medically safe, at least safe from the dread disease that became named “Kuru.” Looking back, however, it appears that some member of the Fore Tribe spontaneously developed Kuru (perhaps as a mutation?). When that person died and was eaten, the infection began.
It took a long time for the symptoms to develop. Case histories said it was from 5 to 50 years until the onset of symptoms, with 10 the median.
The name “kuru,” meant “trembling.” Shivering, trembling was the first symptom. Once the symptoms began, it would take only a year. The victims lost the ability to walk and then control of their arms and legs. Next, control of their emotions disappeared.
Finally, they could not rise, eat or manage their bodily wastes. After death, the unfortunate victims would be ritually eaten, and so things got out of control rapidly.
It was hard for tribal members to see cause and effect because the onset of symptoms took from 5 to 50 years!
It is a long medical and anthropological story about the discovery of the cause of Kuru and its elimination from the tribe by ending cannibalism. Much superstition needed to be fought in the meantime.
However, careful research finally beat down the “alternative facts” that came out of the Fore tradition (such as sorcery). A clincher was the finding that the brains of Kuru-killed dead would also infect and kill chimpanzees they were fed to.
Although it wasn’t recognized for some time, a disease a lot like Kuru was discovered by German neurologists Hans Gerhard Creutzfeldt and Alfons Maria Jakob, in 1920. “Creutzfeldt-Jacob” Disease was (and is) a very rare and widely dispersed disease mostly affecting those over 50 years (although not the very old people).
C-J disease did not crop up in clusters of people like Kuru did. However, its symptoms were almost the same Kuru, as well as being fatal in a year or so after a long incubation. Unlike Kuru, C-J Disease did not seem to be transmissible (until it became obvious that it was).
Unfortunate patients that received corneal transplants, cadaver-extracted pituitary human growth hormone, and similar hormones became infected with the disease. Even instruments used in brain surgery, — well disinfected instruments — transmitted the disease after use on a C-J brain.
In 1997, Stanley B. Prusiner was given a Nobel Prize for discovering Prions, which are merely a protein, but both a new agent of infection and a new form of infection. All past infectious diseases came from an organism that possessed its own DNA — bacteria, viruses, fungi, protozoa, and helminths (worms). A prion does not contain DNA to reproduce. It does not move, nor does it metabolize nutrients. It does not reproduce except for a terribly odd disease-causing kind of copying.
In simple terms, a prion is a misfolded protein that possesses the oddly terrible ability of serving as a template causing large numbers of normal well-functioning proteins in the nervous system to misfold too, triggering awful disease and death.
Prions are additionally dangerous because they are almost indestructible in the environment unless extreme measures are taken.
For example, medical instruments that might have come in contact with them must be pressure boiled in lye (sodium hydroxide) for 30 minutes followed by routine sterilization. On the other hand, land contaminated by prions from infected animals have never been successfully cleared of prions — permanent contamination.
It might seem like the news is good now because we have these unusual dread diseases under control. For example, Kuru is no more. While C-J disease continues at its random once-in-a million emergence, we know now to take special precautions to open the body cavity of a C-J corpse, and especially its cranial cavity lest prions escape into freely circulating air. Medical instruments now are properly disinfected in heat and pressurized lye.
Finally, cattle are (probably) not being made to eat other animals ground up in their feed.
Well, things are not quite that good. First, there’s no cure for a prionic disease, and secondly, a massive wildlife infection of a transmissible spongiform encephalopathy is expanding in parts of the United States (e.g., Wisconsin, Wyoming and Colorado) and Canada. It is called Chronic Wasting Disease (CWD).
There is no evidence CWD infects humans. It might never come to infect humans. But it certainly spreads through deer and elk herds, and infects moose as well. It kills them all unless something else gets them first.
CWD’s symptoms are typical of a spongiform encephalopathy — drooling, staggering, erratic behavior, weight loss. In my writing, I have liked to call it “mad elk disease” due to its similarity to mad cow (and to get reader’s attention).
It isn’t exactly clear how this infection spreads, but infected deer, elk and moose probably do it through direct contact with each other through inhalation, saliva, urine and feces. The density of animals makes a big difference. They might even acquire it from ground and plant contamination deposited previously by infected animals, perhaps a long time in the past.
Shockingly, recent experiments have shown that plants grown in contaminated ground take up the prions, and not just on their surface. Normal plant proteins are converted to prions. These same plants were also shown to infect hamsters when fed to them. So far CWD does not infect livestock.
As I mentioned, the prions resist degradation by sunlight, extreme seasonal temperatures, water, common environmental chemicals, etc. As a result, the spread of the disease to new areas might be permanent even if all infected animals are later removed. “We will worry about it when it arrives,” is not a good strategy.
CWD spread is then extremely bad news for wildlife and for hunters. So we would expect that Fish and Game Departments would react with strong measures to contain the disease. For example, they would not allow herds to gather on grounds for artificial winter feeding.
Think again about that, at least for the State of Wyoming, where now all but two counties are infected. Yet that state maintains a full complement of winter feeding grounds for elk. Meanwhile, CWD creeps ever closer to Idaho, Montana, Yellowstone and Grand Teton National Parks.
Conservation groups have gone to court now and in the past to get these winter feedlots (which are the source of other diseases too) shut down.
Lawsuits have not been very effective against the political power of the Wyoming ranchers who have long supported feedlots for elk in the winter so their cattle can then monopolize natural wintering spots.
There is some optimism that predators and scavengers can retard the expansion of CWD. Clearly mountains lions and wolves target deer, elk and moose suffering CWD, and they can detect it in the early stages before the prion count reaches maximum. These carnivores seem resistant and may be immune to CWD. This is hardly surprising. They must be resistant to many animal diseases or they themselves would have long along perished.
Unfortunately, we are well aware of Wyoming’s attitude toward wolves, bears, cougar, coyotes, etc. outside of the national parks. Ranchers wish there was less wildlife; hunters want more.
This works its way out with ranchers on top seeking to have fewer deer and elk, and a lot fewer carnivores. Hunters have to accept the rancher’s dictate. The rules do allow hunters to dislike bears, cougar, wolves, not to mention what are called “varmints,” because of their take of the already lower-than-they-would-like herd numbers.
It’s a long distance and time from the jungles of New Guinea to the mountains and hills of Wyoming and the farms and forests of Wisconsin. But prions can probably come to infect most natural and artificial habitats.
Dr. Ralph Maughan of Pocatello is professor emeritus of political science at Idaho State University. He retired after teaching there for 36 years, specializing in voting, public opinion and natural resource politics. He has written three outdoor guides, including “Hiking Idaho” with Jackie Johnson Maughan. He is a founder of the Greater Yellowstone Coalition.