The article is from the public number: Glacier Think (ID: icereview) < / a> , author: Zhang Tian Kan.
Hong Kong virologist Professor Guan Yi once predicted,Neo-coronary pneumonia may eventually take off 10 times as much as SARS. When he said this, there were only hundreds of cases of new crown virus infection.
Professor Guan Yi’s words are unfortunately fair. As of February 17, more than 70,000 people have been diagnosed with new crown pneumonia, and more than 1,700 have died.
Although no effective quarantine measures were made at the outset of New Coronary Pneumonia, this time, the low-key strategy adopted by the virus is an important biological reason for the large-scale epidemic.
I. Asymptomatic infection brings more trouble
The low-key strategy of the new coronavirus is that, even if it invades and parasites on people, it doesn’t have a “crown” to celebrate, let alone face the person rigidly. Just like a Trojan horse, don’t let the opponent notice. As a result, asymptomatic infections have occurred. They have no fever, no cough, and no other clinical symptoms. In the end, infection can only be detected through viral nucleic acid testing.
Viruses do this so that people cannot find that they have invaded the human body, making it difficult for them to take early measures to treat the disease and kill the virus.
The low profile of the new coronavirus is also reflected in the fact that it hides in the alveoli deep in the human lungs, and people need to find it. It is very difficult. It cannot be extracted by the throat swab extract alone, nor can its nucleic acid be detected, and it is impossible to confirm the disease by hammer.
Only the lung fluid extracts from critically ill patients can obtain positive results of viral nucleic acid specimens, and many infected people need to repeatedly check the throat swab extracts more than three times to obtain positive results.
Of course, through a series of phenomena and clues, people also know that there are a large number of asymptomatic infections.
Diagnosis and treatment plan (trial version 5) for the first time proposes that asymptomatic infection may also become the source of infection (Figure / Internet)
For example, during the medical observation period, asymptomatic infection was found in close contacts; when some active tests were carried out during the investigation of the aggregated epidemic, asymptomatic infection was found; during the tracking of the source of infection, the exposed population was Asymptomatic infections were also detected during active testing; asymptomatic infections were also found during active testing of people with relevant travel and residence history.
Asymptomatic infection is milder and the virus is less, so the ability to transmit is slightly weaker than in severely ill patients. At the same time, the new coronavirus is mainly transmitted through close-up droplets. Asymptomatic infections are usually less coughing, so the transmission is not very strong.
Even so, people with asymptomatic infection can infect others, and because they are asymptomatic, it is difficult to be identified and prevented. On the contrary, they are more contagious than people with severe illness. many.
This is the reason why the disease has spread widely and infected a lot, and it has also brought great difficulties to disease prevention and control.
Second, SARS is stupid, and the new coronavirus is very smart
The low profile of this virus, such as the absence of fever in humans after infection, reflects a new mechanism for the evolution of pathogenic microorganisms and humans.
The new coronavirus is far more intelligent than the SARS that caused it in 2003. The first symptom is fever. The body temperature often exceeds 38 degrees Celsius. It shows irregular or relaxation fever, retentive fever, etc., and the heat course is more than 1-2 weeks. May have chills, accompanied by headache, muscle aches, general weakness and diarrhea. These symptoms will allow people to quickly diagnose and treat SARS.
However, the new coronavirus does not easily cause symptoms in infected persons, and appears to be concealed. This is obviously a change in the strategy of virus evolution.
One of the asymptomatic or concealed ways is to avoid causing the human body’s over-reaction. Fever is a normal way for the human body to respond to microbial infections and other inflammations. The main purpose is to inhibit viruses or bacteria, and it may even High body temperature kills some pathogenic microorganisms, which is good for physical recovery. Because the new coronavirus, like other viruses, is cold and hot.
On the other hand, although the high toxicity of the virus is an effective means of survival and invasion of other organisms such as humans and large animals, and the virus has no brain and cannot think, but in the process of evolution and mutation The virus will tend to develop towards lower toxicity and greater infectivity.
The two characteristics of low toxicity and stronger infectivity are more beneficial to the virus than high toxicity and infectivity, because this allows the virus to live in the host for a long time and infect more people < span class = "text-remarks" label = "Remarks"> (Host) .
If the virus is too toxic and more infectious, it will cause more hosts to die within a certain period or a short period of time. If the host dies in large numbers, the virus loses its parasitic and attached host, and naturally loses its chance of survival and environment.
For this reason, let ’s call the virus ’s evolution towards low toxicity and stronger infectivity the “intelligence” of the virus, or the evolutionary algorithm formed by the virus ’s survival, loss, and quantity in practice.
The new coronavirus is smarter than SARS. It is because it infects people and can cause asymptomatic infection without fever and symptoms, which helps them not be found, so it can infect more people, and make the virus more effective. Live longer and better.
Three, human body temperature is falling
In fact, for humans, a temperature evolution phenomenon similar to that of the new coronavirus has also appeared, which manifests as the human body temperature gradually decreases.
A measure of whether or not you are infected with the new coronavirus is that the fever exceeds 37.3 degrees Celsius. But why set this temperature as the standard for fever?
This is mainly an average. 37 degrees Celsius is the traditional normal body temperature. However, different parts of the human body, different test times and seasons, and individual differences all affect the temperature readings. Therefore, it cannot be measured at 37 degrees Celsius, but mainly based on the body temperature of different parts of the body.
The body temperature of common parts of the body includes oral cavity temperature, rectal temperature and axillary temperature. Oral temperature is 36.3-37.2 degrees Celsius; axillary temperature is currently the most commonly used temperature measurement method, the normal range is 36.1-37 degrees Celsius; normal rectal temperature is about 0.3-0.5 degrees Celsius higher than oral temperature. Therefore, rectal temperature is highest,Oral temperature was next, and armpit temperature was the lowest. The combined balance of these three factors also led to a fever of 37.3 degrees Celsius.
Fever is divided into several levels. 37.4-38 degrees Celsius is low heat; 38.1-39 degrees Celsius is moderate heat; 39.1-41 degrees Celsius is high heat; 41 degrees Celsius is super high heat. Of course, these fevers must go directly to the hot clinic to confirm what is causing it.
The team of infectious disease epidemiologist Passionette of Stanford University in the United States has analyzed and analyzed more than 677,000 temperature measurements of Americans since 1860. According to calculations, the average body temperature of modern people is higher than that in textbooks. The temperature of 37 degrees Celsius is lower, and it drops by a few ten degrees every 10 years.
This appears on several time nodes. In 1851, the German physician Carl Windlich determined for the first time that the normal body temperature should be 37 degrees Celsius. In 1992, Mark Tuvik’s team of infectious disease physicians at the University of Maryland School of Medicine tested 148 people participating in the vaccine trial and found that their average temperature was 36.8 degrees Celsius. In 2017, a study of 35,000 people in the UK found that the average body temperature of these people was 36.6 degrees Celsius.
Karl Windlich (Picture / Web)
As a result, researchers generally suspect that 37 degrees Celsius is not a normal body temperature. However, the suspected target first was the inaccuracy of the thermometer, such as Mark Tuvik’s opinion that in the Wendrich era, the thermometer used was too high, even exceeding 1 degree Celsius.
Therefore, Maktovik believes that measurement errors are the main reason for Windelich to set 37 degrees Celsius as the average body temperature of a person.
But it was later discovered that people who were born earlier often had higher body temperature than people who were born later. People’s great-grandparents and ancestors had higher body temperature than modern people, and even when the temperature was measured during the same period. Therefore, Parsonette et al. Believe that if only the thermometer has changed, thenThe year the temperature was measured should have a different effect, but it is not.
The fundamental reason is that the lower infection rate in modern people is probably the most important reason for the drop in body temperature .
For example, people with long-term infections such as tuberculosis and gum disease can increase human body temperature due to inflammatory immune response in the body. However, due to the use of antibiotics and other drugs, modern people are less likely to be infected with microorganisms and for a shorter period of time, which also causes a drop in body temperature.
Four, lower the fever standard to deal with the low profile of the virus
The low profile of the new coronavirus, in addition to making it more difficult for humans to fight the epidemic and causing more people to be infected, has several possibilities in the future.
The first possibility is that it will evolve into another unnoticed coronavirus, similar to the other four coronaviruses that cause common colds and mild respiratory diseases, becoming the fifth epidemic coronavirus.
The second possibility is that the new coronavirus will recur in winter like influenza virus, and it will also cause serious consequences, and critically ill patients may die, just like this outbreak.
The third possibility, as stated by the Director-General of the World Health Organization, Tan Desai, The low profile of the virus has caused people to underestimate its threat, making the spread of the virus more than any terrorist action can The consequences will be great, and the world must soberly treat this virus opponent as the number one public enemy!
Tan Desai, Director-General of the World Health Organization (picture / web)
In this case, the body temperature should be measured by a lower temperature standard, for example, 37 degrees Celsius,Reverting an asymptomatic person to a symptomatic person, at least a mild patient, can also prevent more sources of infection. Because the new coronavirus does not cause fever, it just causes fever lower than 37.3 degrees Celsius.
When a new coronavirus causes people to reach a temperature above 37 degrees Celsius, even if they have a fever, it will cause people to be alert and prompt them to undergo nucleic acid tests and other clinical tests in order to confirm the infection and reduce the number of asymptomatic patients Treat symptomatically and isolate them to reduce infections to other healthy people.
In this way, it will help to control the epidemic more quickly and effectively, and defeat the disease.
The article is from the public number: , author: Zhang Tian Kan