Do you still have an impression? There is a poison in the film and television drama "Tang Bohu Dotting Autumn Fragrance" - laughing half-step madness, and it is said in martial arts novels that as long as you take this medicine, you can no longer laugh, or even walk, otherwise you will die violently.
Laughter is not uncomfortable, but laughter will not only make people uncomfortable, today we want to talk about the prion, the disease it causes will make people "laugh to death", it is said that its fatality rate is as high as 100%! To know that the case fatality rate of the new crown in 2020 was 2.33%, and the fatality rate was only 0.08% in December 2022, what is so special about such a virus that is more terrible than the new crown?
I. A strange disease that makes people "laugh to death"? Let's hit the "past and present lives" of prions together!
Just over 60 years ago, Papua New Guinea in Oceania had a terrible epidemic of strange disease, when people with the disease could not speak clearly, as the disease progressed, they would directly lose their ability to speak, and even laugh uncontrollably, and eventually the patient would be tortured and die in pain!
It was then called Kuru disease because the local language "Kuru" means "to die of laughter."
But what is really strange is that Kuru disease seems to only target the "Fore" tribe in Papua New Guinea, and none of the other tribes have the disease, and even if they do, they are all tribes closely related to the "Fore" tribe. People at that time were eager to find answers to their questions, and without saying a word, they linked the disease to the curse of wizards. Now from an epidemiological point of view, this explanation is completely implausible, until a doctor from the United States, Daniel Gaidusek, changed everyone's opinion.
It was believed that Kuru disease was spread by eating dead people.
Doctor Daniel Gaidusek realized that the "Fore" tribe was very special, and the local people had a custom of "ritual cannibalism". When one member of the tribe dies, the others hold a memorial service and eat the dead person's body, including muscles and even brains. Because of this, American doctors have come to the hypothesis that Kuru disease is a contagious disease transmitted through brain tissue.
But this hypothesis holds a condition, that is, the patient's brain tissue is transplanted into the animal, and the animal must have the disease. So American doctors implanted the brain tissue of people who died in Kuru disease into the brain of chimpanzees, but they did not expect that chimpanzees really had symptoms of Kuru disease, so the hypothesis of American doctors is valid.
What kind of virus is Kuru disease?
In 1977, the California chemist Bruchner had been studying a disease called "K-Jakob disease", and he found that the disease was not a virus, but a protein, which is what we now call prions, and it cannot be ignored that it is also a pathogen of Kuru disease.
Two. The fatality rate of prions is as high as 100%, which can be called a "missile" shot at the human brain, how terrible is it after infection?
Current research shows that prions can cause damage to the central nervous system in animals and humans, and are a fatal disease, which is caused by unconventional pathogenic agents. In general, animals can be infected by eating the internal organs and meat of animals with prion disease, while humans are often infected through iatrogenic infections such as blood transfusions and corneal transplants, and eating the meat of animals with the disease.
It can be seen that the potential source of infection of prions is very large, and the unknown potential host may be more extensive, so it is difficult to predict and infer the risk of its transmission. However, we need to know that because prions can cause multi-organ infections, and mainly cover the cerebral pulp, it is actually very difficult to prevent it, whether it is people or livestock, as long as the disease occurs, all deaths will be in half a year to a year or so, and the fatality rate can reach 100%!
How scary can it be when you are infected with a prion?
Normally, prions exist in the form of harmless cellular proteins, but at the same time they may transform their structures into harmful particles, causing fatal encephalopathy in humans and animals. For example, animals infected with prions may develop mad cow disease, scrapie, etc., while humans can have new variants of Creutzfeldt-Jakob disease and fatal familial insomnia.
Among them, after animals are infected with prions, they may show aggression, trembling, falling to the ground from time to time, etc., and may also appear excited and loss of appetite in the early stage, but as the disease progresses, neurological symptoms will become more and more obvious, until they fall to the ground and die.
The new Creutzfeldt-Jakob disease, which has appeared in the human population, may be caused by the transmission of mad cow disease. As early as 1995, about 20 patients were diagnosed with new Creutzfeldt-Jakob disease, often manifested as difficulty walking and instinctive muscle contractions, of which mental depression is the main psychological symptom, lasting about 6 months in the early stage, after which patients will quickly appear anxiety, depression and other mental symptoms.
It is worth noting that when these clinical symptoms appeared, the average survival time of patients was only 14 months, which may be related to the characteristics of prions. The pathogen of prion disease in humans and animals is actually prions, which cause the death of central nervous cells, resulting in psychiatric symptoms.
But don't worry too much, the fatal disease caused by prions in the population is not much, take the new variant of Creutzfeldt-Jakob disease, although its fatality rate is high, but in 1996~2015, a total of 228 cases occurred worldwide, of which 2012~2013, even only 1 case occurred every year, which can be said to be a "rare disease".
Three. Prions cause mostly rare diseases, so the impact on most people is small?
Since prions are mostly rare diseases, it is true that it does not affect most people, and more affects a small number of people, but we still need to be vigilant about the pathogenic pattern of prions, because its rapid progression may cause Alzheimer's disease.
The peculiarity of the pathogenic mode of prion is reflected: the normal protein in the human body acquires an abnormal conformation for some reasons, which is multifaceted to the body. For example, it will not only damage cells, but also make proteins with normal conformation abnormal, eventually leading to human diseases, the most typical of which is neurodegenerative diseases.
Such as Alzheimer's disease, Parkinson's disease and other neurodegenerative diseases, and these diseases are actually very common in life, we often hear about it in reports, relatives and friends, especially Alzheimer's disease. These neurodegenerative diseases have a common feature - there is usually a buildup of a certain protein in the patient's brain tissue, such as the accumulation of Tau protein, β-amyloid in the brain of Alzheimer's patients, and the spread of Tau protein accumulation can be linked to cognitive dysfunction.
It can be seen that the similarity of these diseases is very high, but neurodegenerative diseases involve many factors, and they are more complex in comparison, so the pathogenesis of these diseases cannot be simply equated with prion diseases, which belongs to the field that scientists actively study, we only need to have a clear idea.
It should be noted that there is currently no effective vaccine for prion virus infection, and prevention and control measures are still mainly based on culling sick animals and their offspring, in addition to strengthening customs inspections, avoiding the introduction of animals from diseased areas, and strengthening research on prions.
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