"The only lesson that mankind has learned from history is that mankind cannot learn any lesson from history. —Hegel didn't say it"
The Spring Festival of 2020 is probably the most boring and heart-wrenching holiday for all Chinese, and the fierce new crown pneumonia is like the sword of Damocles hanging on the head, which makes people full of uneasiness and anxiety. Although the epidemic has not improved until now, I have always believed that the virus will eventually be defeated by humans.
Looking back at the causes of the epidemic, we will find that this new crown pneumonia, which originated in Wuhan and eventually swept the whole country and even the world, once again told us with a cruel reality: "The only lesson that mankind has learned from history is that human beings cannot learn any lesson from history." ”
It is well known that the SARS virus that broke out in 2002 originated from civets in the wildlife trade market, because the first infected people were market traders, as well as chefs, waiters and diners, all of whom had close contact with or direct consumption of civets. But two years later, through investigation and analysis, virologists confirmed that the civet cat was only an intermediate host, and the real source of the virus was the Chinese chrysanthemum bat.
The new crown (NCP) and SARS are both coronaviruses, and the first patient is from the Wuhan Huanan Seafood Market, which is a well-known illegal wildlife trading market, so the outbreak of this epidemic is likely to be the same as SARS. Therefore, when tracing the source of the virus, virologists naturally set their sights on the Chinese chrysanthemum bat.
Chinese chrysanthemum bat
According to the genetic sequencing results of the research team of Shi Zhengli, a famous virologist in China, the sequence similarity between bat coronavirus and new coronavirus has reached 96.2%. A WHO report released on 11 February also shows a growing body of evidence linking the coronavirus and the coronavirus (CoV) transmitted in the bat subspecies of Chicory bat. It can be seen that the Chinese chrysanthemum bat is likely to be the natural host of the new crown virus.
Like the SARS virus, in addition to the natural host, the new crown virus should have an intermediate host. On September 30, 2019, in an international journal editor, a researcher published an article about pangolins, the author mentioned that the Guangdong Wildlife Help Center obtained 21 Malayan pangolins from the Anti-Smuggling Bureau on March 24, 2019, and the sequence of coronaviruses was found in two of them.
According to this article, a scientific team soon found that a β coronavirus was indeed found in some pangolins, and through further isolation and identification, it was found that the sequence similarity with the currently infected human novel coronavirus strain was as high as 99%, so it was highly suspected that pangolins are the intermediate hosts of the new coronavirus.
Judging from the seizure of 21 Malayan pangolins by the Guangdong Anti-Smuggling Bureau, we can imagine that there will definitely be fish that have slipped through the net and entered the wildlife trading market in various parts of the country through other channels, including Wuhan. Although there are no pangolins in Wuhan's infamous "game menu", it should not be unusual to illegally sell pangolins here.
Internet rumors about Wuhan's infamous "game menu"
As for how the virus on the bat spreads to the pangolin, some scholars speculate that the pangolin likes to be in a dark cave, and the bat also likes, it is possible that the two appear in the same cave, the former contacted the coronavirus in the feces of the latter, resulting in the reorganization of the virus in the pangolin, becoming a new coronavirus, and then transmitted to humans.
Of course, whether pangolins are intermediate hosts for the new coronavirus is debatable, but according to the previous outbreak and epidemic of the SARS virus, the possibility that the new crown pneumonia is caused by humans through eating and contact with wild animals is very high. In fact, most of the highly contagious viruses we currently know are infected by humans through contact with or eating wild animals.
The following infectious diseases caused by viruses are believed to be familiar to most people.
<h1 class = "pgc-h-arrow-right" > plague</h1>
The plague, once known as the "Black Death," "slaughtered" nearly 30 million Europeans in the three years from 1348 to 1350, and nearly one-third to half of Russia's population died at the time. Plague also has a large-scale epidemic in The history of Our country, such as the Northeast Plague Incident in 1910, after the founding of New China, there are still sporadic cases in the west and northwest.
Plague, a virulent infectious disease caused by Yersinia pestis infection, is currently the first of 39 notifiable infectious diseases due to its enormous impact. Clinical manifestations are high fever, lymphadenopathy and pain, cough, sputum production, dyspnea, bleeding, and other severe symptoms of poisonous blood. The disease is highly contagious and has a high case fatality rate.
Plague was first endemic among rodents, such as rats (of which brown and yellow-breasted rats were the main source of infection), marmots, etc., which were naturally the original natural reservoirs of such viruses. According to research, the way that plague spreads to humans is through the bite of rat fleas, which transmits the pathogen (Yersinia pestis) in rodents to humans, forming a transmission method of "rodent → fleas → people".
Logically, rat fleas generally rarely bite people, and rodents have enough blood to survive, but all this changes with Yersinia pestis. This germ will multiply in the digestive tract of rat fleas to form embolisms, blocking its digestive tract, so rat fleas become "hungry ghosts", how to eat is not enough, so they will desperately look around for a source of blood that can be sucked, and humans will bear the brunt.
In addition, because the digestive tract of the rat flea has been blocked by Yersinia pestis, when it sucks human blood, it will eventually cause excessive pressure in the digestive tract because it "cannot swallow", resulting in the liquid that has been inhaled and regurgitated with the plague bacillus in the digestive tract, thus spreading the plague to humans.
The first patient infected with plague formed human-to-human transmission through respiratory droplets, causing a large-scale epidemic in society. In addition, Yersinia pestis can also be transmitted by contact, and infection can occur when a healthy person's broken mucous membranes are in contact with the patient's pus, blood, sputum, or with the skin and flesh and blood of a diseased rodent.
It is worth saying that in the Northeast plague incident in 1910, the international medical community's understanding of the spread of plague at that time was that it would only be transmitted to people through rats (fleas), and there would be no infection between people, and the way to eliminate the plague was to exterminate rats. However, this view was overturned by the then commander-in-chief of epidemic prevention, the medical god Wu Liande (Malaysian Chinese).
The reason is that Wu Liande disregarded the risk, dissected the body on the spot with the assistants in the epidemic area, and found a large number of plague bacteria in the heart, lungs and blood of the deceased patient. Therefore, he determined that the plague was transmitted from person to person through breathing and saliva, not rats, and that an effective way to eliminate the plague was to isolate the patient and burn the infected corpse.
Wu Liande's conclusions were finally recognized by the medical community, and with the support of the Qing government, the northeast began to carry out comprehensive control, all public facilities, hotels, restaurants, shops, were fully disinfected, patients and family members were strictly isolated, and those who might be in contact with patients had to stay at home and isolate themselves. The plague that ravaged the northeast was thus eradicated.
< h1 class = "pgc-h-arrow-right" > the HIV virus</h1>
Modern people are no strangers to AIDS, which is a very harmful infectious disease, caused by sexual, blood, maternal and infant infection with HIV virus (HIV virus). HIV is a virus that attacks the body's immune system. It takes the most important CD4T lymphocytes in the human immune system as the main target, destroying a large number of this cell and causing the body to lose immune function.
Therefore, the human body will have a variety of infections due to the extreme decline in the body's resistance, such as shingles, oral mold infection, tuberculosis, enteritis, pneumonia, encephalitis caused by special pathogenic microorganisms, candida, pneumocystis and other pathogens caused by serious infections, etc., malignant tumors often occur in the later stage, and long-term consumption occurs, and even death from systemic failure.
The incubation period of the HIV virus in the human body averages 8 to 9 years, and before developing AIDS, it is possible to live and work for many years without symptoms. The first case of AIDS detected by humans was a man in the Congo in Africa in 1959, and by 1980, there were 100,000-300,000 infected patients worldwide, and since then it has grown rapidly year by year, reaching 37.9 million infections by the end of 2018.
At present, the mainstream of the scientific community believes that the HIV virus originates from chimpanzees and is transmitted from SIV (monkey immunodeficiency virus) across species. As early as 1999, researchers discovered SIVcpz in a chimpanzee, and then they found that the virus was very similar to the HIV virus in humans, and began to trace the source of SIV.
Through understanding, the researchers found that chimpanzees liked to hunt two other monkeys (red-topped whiteheads and nose-spotted monkeys), and they found two different SIV viruses in both monkeys. Therefore, the researchers concluded that chimpanzees, when preying on these two monkeys, do not infect the two SIV viruses, and then combine in the body into a third virus, called SIVcpz, which can infect each other between chimpanzees and humans.
At that time, it was more popular to hunt chimpanzees in Africa, so scientists believe that it was the local people who achieved cross-species transmission due to various reasons, such as blood contact when cutting chimpanzees, siVcpz thus achieved cross-species transmission. Of course, at the beginning, the human body itself is not so fragile, the immune series will kill these viruses, but over time, the virus in the body more, it began to mutate, the formation of HIV virus left in the human body.
Off-topic, the first case of AIDS infection in 1959 was detected with a blood sample, but it does not mean that it is the first case in the true sense of the human race, because scientists used his HIV samples, traced back to several generations, and finally concluded that the first SIV to HIV cross-species transmission was in Kinshasa, Congo in 1920, which is the most abundant area of HIV strains, indicating that many of the local HIV is transmitted by SIVcpz cross-species. Unlike other places, it is basically human infection.
<h1 class="pgc-h-arrow-right" > Marburg virus</h1>
Although the virus takes the name of the German town of Marburg, it actually originated in Uganda, Africa. In 1967, a German pharmaceutical company imported a group of African monkeys called Cercopithecus aethiops (aka African green monkeys) in Uganda to study several medical laboratories in Marburg, Frankfurt and Belgrade, Yugoslavia, to develop a vaccine for polio.
However, before long, a total of 31 staff members in the three places contracted the disease at the same time, of which 7 died, with the same initial clinical symptoms. Later, through investigation, it was found that they were infected with a virus from the African green monkeys of the experimental subjects, 25 people were directly infected, and the rest were transmitted between people, including two doctors, a nurse, an anatomy assistant, and a veterinarian's wife.
Since the virus was first discovered in Marburg, the medical community named the town. Subsequently, outbreaks of Marburg virus in Africa were endemic in South Africa, Kenya, the Democratic Republic of the Congo, Angola, and Uganda, and the number of infected people increased at a larger rate, while most of the patients died within a week after the onset of the disease, with a mortality rate of 25% to 100%.
Marburg virus is the first discovered fibromitavirus, highly contagious, the incubation period is generally 3 to 9 days, children are the most susceptible group, in the African region where the virus is endemic, 75% of cases occur in children under 5 years of age, adult infected people are mostly close contact with infected children relatives and health care workers.
After people are infected with the "Marburg" virus, the initial stage is very similar to the flu, there will be fever headache, muscle pain and other phenomena, followed by a systemic rash, vomiting, diarrhea, etc., and finally there is bleeding from the various holes in the body. The "Marburg" virus is transmitted by contact, mucous membranes and broken skin, and by blood, secretions, excrement, vomit, and droplets.
Although virologists first discovered the Marburg virus in African green monkeys, they were also victims, i.e. intermediate hosts. Later, virologists found the "Marburg" virus in the north African fruit bat (rousettusaegypti) and the pteropodidae fruit bat, plus the "Marburg" virus endemic areas in Africa, which regarded such bats as a delicacy, so fruit bats are most likely the original host.
At present, the outbreak of the "Marburg" virus is limited to Africa, due to the extremely backward medical level of the local area, coupled with the habit of hunting wild animals, resulting in the repeated epidemic of the "Marburg" virus. In February 2018, WHO declared Marburg virus one of the ten deadliest viruses in the world based on its infection rate and fatality rate.
<h1 class="pgc-h-arrow-right" > Ebola virus</h1>
In 1976, an unknown infectious disease was circulating in southern Sudan and Zaire, now the Ebola River region of the Democratic Republic of the Congo, and 55 villages in this area were recruited, and some families were not spared, and then mysteriously disappeared. Three years later, the virus reappeared, and the nearby corpses were once again scattered in the wilderness, and then mysteriously disappeared without a trace.
Fifteen years later, in 1995, the virus once again emerged in the Gabonese Republic of Africa, with case fatality rates of 90 per cent in some cities, so the World Health Organization listed it as one of the most harmful to humans, the "fourth-degree virus" (the larger the number of levels, the more toxic, the third degree of AIDS). The medical community named the virus "Ebola" based on its original origin.
Through investigation, researchers found that the "Ebola" virus and the "Marburg" virus belong to the same fibromitonyvirus, the incubation period is 2-21 days, after human infection, the virus will rapidly multiply, encroach on various organs, resulting in deformation, necrosis, and slowly decomposition. The infected person first suffered internal bleeding, then seven bleeding incessantly, uncontrolled vomiting, and finally died due to extensive internal bleeding, brain damage and other causes.
The transmission of "Ebola" disease is mainly contact transmission, which is transmitted from person to person through blood, saliva, sweat and secretions in patients who have symptoms, but there is scientific and epidemiological evidence that Ebola virus may be transmitted through aerosol particles, that is, airborne transmission, which indicates that masks can no longer be stopped and require breathing masks.
In order to determine the origin of the "Ebola" virus, French scientists have captured thousands of different animals in the Ebola River region, including bats, birds, squirrels, etc. for virus testing, and the Ebola virus has also been found in 29 fruit bats in the local area, so it is suspected that fruit bats are also the natural host of Ebola virus.
However, more studies have found that other local wild animals also have Ebola virus, such as chimpanzees, monkeys, rats, and wild boars, so there is still no conclusion as to who is the host of the "Ebola" virus. But what is certain is that in Africa where the "Ebola" virus is endemic, locals have a custom of preying on these wild animals containing the "Ebola" virus in their bodies.
Therefore, it is certain that "Ebola" is an infectious virus that humans have contracted through contact with and eating wild animals, and it is one of the most terrible viruses that humans have ever known. In the words of one doctor, a patient infected with the "Ebola" virus will "melt" in front of you, and the only way to stop the spread of the virus is to completely isolate the infected patient.
<h1 class="pgc-h-arrow-right" > MIDDLE East respiratory syndrome</h1>
In September 2012, the UK Health Protection Agency (HPA) reported to the WHO that a Qatari man with an acute respiratory infection had been diagnosed with the same novel coronavirus as a Saudi man who died in the Netherlands at the beginning of the year while seeking medical treatment in the UK. Subsequently, the virus has been reported in some countries in the Middle East and Europe.
Because the virus first appeared in the Middle East, who (WHO) named middle east respiratory syndrome (MERS), with an incubation period of 5 to 14 days, and the clinical symptoms of infected people include fever, cough and dyspnea, pneumonia, renal failure and diarrhea and other gastrointestinal symptoms. The known modes of transmission are mainly droplet transmission and contact transmission.
In May 2015, south Korea suddenly appeared the first case of Middle East respiratory syndrome patients, only three weeks, the epidemic spread rapidly across the country, due to poor control, opaque information, resulting in the closure of more than 2,000 schools in South Korea, a large number of public activities cancelled, tourism has also been hit hard. In the end, the outbreak lasted seven months before it was brought under control, resulting in 187 infections, 38 deaths and nearly 17,000 quarantines.
According to current data, although the fatality rate of MERS is higher than SARS (the former is about 30%, the latter is about 10%), it is less contagious than the latter, and generally cannot be continuously transmitted between people, but the risk of close contact with patients is greater, so in areas with severe epidemics, the risk of medical staff being infected is greater.
Egyptian tomb bat
Because MERS and SARS are the same coronavirus, and bats are natural hosts for many coronaviruses, virologists initially suspected that the virus came from bats, and eventually they searched throughout the Middle East, detecting only a RNA virus with some fragments of the same fragments as MERS in bat feces called the Egyptian tomb bat.
However, Egyptian tomb bats have less contact with the locals, so scholars believe that there must be other animals as intermediate hosts. Through extensive sampling, they found that 74% of the samples showed positive MERS antibodies in more than 200 dromedary camel blood samples, and the MERS virus in the camels was as similar as the virus in humans by up to 99.9%, so therefore.
So how camels are transmitted to people, the November 2013 MERS death case provides a way of thinking, the report of the deceased is a 44-year-old Saudi man, who raised 9 camels before his death, 4 of which had runny nose and other symptoms, the man smeared the camel's nose a week later, the symptoms of MERS infection.
However, virologists have also found that MERS can also infect primates, rabbits, goats and other animals, so it is suspected that MERS first spreads among animals, then spreads from multiple sources to people, and then spreads from person to person. Saudi Arabia and South Korea, the two main regions where cases of Middle East respiratory syndrome (MERS) are currently increasing, do not yet have vaccines or specific treatments for the virus.
<h1 class="pgc-h-arrow-right" > Hanta Virus</h1>
Although this virus is not famous as the previous ones, it is also extremely lethal and belongs to the spherical virus, but it is as "fickle" as the coronavirus, and the more terrifying evolutionary function - host co-evolutionary function, showing extraordinary diversity. In studies in recent years, a total of 34 genotypes of hantavirus have been identified, of which at least 22 types have been shown to cause disease in humans.
Hantavirus was first confirmed after an outbreak in the southwestern U.S. states in 1993, but there were already many cases before that. It has an incubation period of up to 9 to 35 days, a mortality rate of up to 50% to 75%, and after invading the human body, like the Ebola virus, it can cause bleeding, kidney damage and immune dysfunction, but after healing, permanent immunity (that is, antibodies) can be obtained.
The main clinical manifestations of human infection with hantavirus are fever, headache and other symptoms, and a few days later, non-cardiogenic pulmonary edema and acute respiratory failure, that is, hemorrhagic fever of renal syndrome common in China, severe disease dies for 3 to 7 days, and mild diseases recover quickly through treatment. Although there has not been a single case in China so far, it is still possible because the intermediate host of the virus is everywhere.
Virologists through the investigation found that the original host of hantavirus is a rodent, that is, rodents, from the current research report, although there is no human infection with hantavirus in many parts of the world, but in the local rodents still isolated hantavirus, which means that any place may break out.
Thankfully, there is currently no evidence that hantavirus can spread from person to person. The main ways of human infection: viruses in rodent urine, feces, and saliva attach to dust particles in the air and are inhaled into the body; infected by rat bites or wounds that come into contact with rat excrement containing viruses; viruses in rodent urine, feces, and saliva can contaminate food, and eat contaminated food is infected.
The above are the more well-known deadly viruses that humans currently infect from animals, and some of them, such as rabies virus, dengue virus, and avian influenza virus, are also source animals. Some are passive infections that viruses are no wonder avoided, but some are actively infected by us humans.
<h1 class="pgc-h-arrow-right" > written at the end</h1>
Medicine, the infection of humans through animal infection is collectively called "Zoonosis", which has existed since ancient times, but in modern times, the livestock and poultry we eat will be vaccinated against viruses, so there is rarely a risk of infection with the virus. However, due to various cross-contact in wild animals, the body may carry the virus, and people may be infected if they touch and eat.
According to a paper published in the journal Nature in 2008, among the more than 300 new infectious diseases that emerged in humans from 1940 to 2004, the proportion of zoonotic diseases was 60.3%, of which 71.8% came from wild animals, and poultry and livestock were less than one-third, so keeping your mouth shut and not eating everything was the best way to prevent new infectious diseases.
In the above virus introduction, we will also find that bats are the natural host of a variety of viruses that are currently known, and virologists have detected 137 viruses in their bodies, of which 61 are zoonotic viruses. In addition to the viruses described above, hendra virus, Nipah virus, Japanese encephalitis epidemic virus, Timan virus, Ross River virus, chikungunya virus and forest encephalitis virus are all from bat families.
Many people wonder why so many viruses are set in one, but the bats themselves do not have a little, in fact, this is only a superficial phenomenon. Because humans have not studied the impact of viruses on bats, who knows if they also have to endure the torment of the virus all the time, and their life expectancy has been greatly reduced.
Of course, zoonotic diseases can not be eliminated, after all, human beings are also part of nature, it is impossible not to contact wild animals at all, and now poultry and livestock, chickens, pigs, cats, dogs may also be the intermediate host of the virus, so humans still manage their mouths, do not eat everything, you can effectively reduce the outbreak and epidemic of new infectious diseases.