Ms. Zhang's daughter is more than two years old, and her grandfather had a birthday the day before yesterday, so Ms. Zhang took her daughter to the banquet together, but when she returned home in the evening, her little daughter felt unwell and began to have a fever and runny nose. At first, Ms. Zhang thought that her daughter was just suffering from a cold and had a cold, so she didn't pay much attention to it, but just fed a little medicine.
But in the middle of the night, her daughter kept crying, and Ms. Zhang, who woke up, touched her daughter and felt that it was very hot, and the temperature turned out to be almost 40 degrees.
Ms. Zhang was sleepy all of a sudden, and came to the hospital with her daughter in her arms, and the doctor said that it was a high fever caused by the child's infection with influenza A, but fortunately it came in time, and the flu was much more dangerous than the common cold.
Yes, when it comes to the topics that everyone is discussing this year, it is estimated that many of them are influenza A and influenza, so what is the difference between cold, influenza A, influenza B and the new crown? Why is the flu more serious than a cold?
First, the first stream and the second stream are coming? The child has a serious cold? We must first understand the difference between them
In fact, a cold is a more colloquial term, which refers to an upper respiratory tract infection.
Nature is full of viruses and bacteria, and in most cases, our nose and mouth are directly connected to the outside world, so when these microorganisms invade the human body, they often "march" into the respiratory tract through the mouth and nose.
Under normal circumstances, a few small viruses and small bacteria will not cause any effect on our body, but when our immune function is reduced, especially in winter, the blood vessels in the whole body are constricted, and the blood flow rate slows down, which will cause the proliferation of immune cells to be slower, the virus will induce infection.
Therefore, the respiratory tract is the most exposed body tissue to bacteria and viruses, and upper respiratory tract infections, also known as colds, are one of the most common diseases in the human body.
The common cold is mostly caused by rhinovirus, coronavirus, and some bacteria, which are weak and easy to be dealt with by our immune cells, so sometimes the common cold doesn't even need to take medicine, and it is good to stay up for three or five days.
But the question is, what if the virus is very powerful?
For example, the new crown virus that broke out all over the world before was highly virulent, multiplying quickly, and there were many variants, and our immune cells were not opponents of the new coronavirus under normal circumstances, so its pathogenicity and infectiousness were far better than the common cold.
Then the so-called influenza is also the same truth.
They are respiratory infections induced by influenza viruses, and the power of the pathogen is not at all comparable to ordinary rhinoviruses. Influenza viruses can be divided into four virus strains, namely influenza A, B, C and D, according to the differences in proteins, which are what we call influenza A, B, C and D.
Influenza A virus is the most common, and its host is so wide that almost all mammals, including humans, as well as bats and birds, can be infected by it. In addition, according to the differences in glycoproteins on the surface of the virus, 25 different subtypes can be distinguished, which are still known to humans, excluding undiscovered subtypes.
Moreover, influenza A can also break through the species barrier and complete cross-host transmission through genetic recombination, such as avian influenza, which is a subtype of influenza A, but can also cause human infection.
Therefore, influenza A is not strange to human beings at all, and many influenza outbreaks in human history were induced by this grandfather's family, which can cause influenza outbreaks, which is enough to show that influenza A is very pathogenic and infectious.
Speaking of influenza B, its characteristics are very similar to influenza A, but the ability of influenza B is far inferior to influenza A, so influenza B does not have the ability to cause a flu outbreak.
Influenza C is a pathogen that tends to occur in the respiratory tract of children, but there are few studies at present, and flu C is an influenza virus that has only been discovered in recent years, and no human cases have been found so far.
No matter what the virus is, it will cause respiratory infections, and we have also said that the difference between the flu and the common cold lies in the ability of the virus, that is, the difference in pathogenicity, and the damage of the flu virus to the human body is far better than that of the common cold. Do you know the reason behind it?
2. Why is the flu stronger than the cold? The virus is not in the same category
The pathogenicity of influenza viruses depends on the function of the viral proteins and the immune response of the host.
In the early stage of infection, influenza virus can enter the cytoplasm of normal cells through the form of viral envelope-endosomal membrane, thereby damaging normal cells, which is the beginning of the onset of influenza virus.
Specifically, influenza virus, as a cytolytic virus, can induce apoptosis in a variety of normal cells, including epithelial cells, monocyte macrophages, and vascular endothelial cells. In the most popular case, when the cells of the respiratory tract are infected with a virus and diet in a large area, we will have a series of inflammatory symptoms, including red and swollen throat, sore throat, etc.
The common cold virus can also cause throat discomfort, but the severity and duration of symptoms are actually inferior to the flu virus. What is more frightening about the flu than the common cold virus is that it can more easily reach the lungs to "wreak havoc".
For example, influenza viruses can burrow into lung cells, disrupt the integrity of cell membranes, cytoplasmic osmotic pressure, and cause swelling of organelles, initiating necroptosis. If the disease is mild, the active substance in our body is able to block the necrosis signal, thus protecting the normal lung cells.
However, if necroptosis is not controlled, large areas of epithelial cells in the bronchoalveoli can die, causing acute respiratory distress syndrome.
Moreover, excessive necroptosis can affect the clearance of cellular debris and tissue repair, thereby inducing an inflammatory response and causing severe lung damage, which can be fatal, especially in young children whose lung function is not fully developed.
In conclusion, influenza A can be infected through viruses, especially necrotizing cell apoptosis, to induce respiratory distress syndrome and even pneumonia, which is the first difference between influenza A virus and the common cold.
Furthermore, when it comes to colds, we have to talk about the immune system.
For the common cold, our immune system is able to quickly destroy the virus in a short period of time, and kill the virus by expelling the virus through phlegm and coughing or raising body temperature, such as coughing, spitting and fever itself is a manifestation of our immune system killing the virus.
However, in the case of influenza viruses, in many cases, the immune system is not able to handle it, which causes the immune system to become too strong, so the symptoms such as cough and fever may become more severe, so the fever of flu patients is higher than that of the common cold, and the same is true of cough.
In addition, because the immune response is too strong, it can also activate related inflammatory pathways, releasing pro-inflammatory cytokines such as tumor necrosis factor α and interleukin. These things are involved in a cascade called a cytokine cascade that induces acute lung injury.
In addition, if the inflammatory factors are too strong, they will lead to enhanced vascular permeability and destroy the physical barrier in the lungs, which will lead to inflammation in the lungs and induce pneumonia.
Therefore, in the face of powerful viruses such as the new crown and influenza A, we often stimulate specific antibodies, that is, vaccines, to promote the differentiation of immune cells such as T cells and efficiently eliminate the virus. So it can be seen that the difference between the flu and the cold is actually more of a difference in symptoms.
3. The flu is the highest in autumn and winter, do these things well, and stay away from the virus as much as possible!
We all know that both the flu and the cold can cause symptoms such as fever, cough and sore throat, but the flu virus is stronger, destroys normal cells and activates the immune system, so even if the symptoms are the same, the symptoms of the flu are significantly more severe, and it is difficult for the body to overcome it on its own.
Generally speaking, the fever of common cold patients lasts for one to two days, and the fever is mostly below 39 degrees, while the fever of influenza patients lasts for 3~5 days, and the fever is mostly 39~40 degrees, or even higher.
In addition, patients with influenza are more likely to have complications, the most typical of which is lung disease, including inflammation, etc., and some patients will have symptoms such as otitis media and myocarditis due to the spread of the virus and even invasion of other systems.
The risk of these complications is very, very low in people with the common cold. Influenza viruses are not only highly pathogenic, but also highly contagious, but influenza viruses have obvious seasonality, mostly in autumn and winter, and the common cold is not.
So how to prevent the flu in the cold winter?
The first is to do a good job of personal protection, it is best to wear a mask when going out, try to keep a distance from others, wash your hands more, drink more water, rest more, try to stay away from the virus, and if you have children at home, you can also appropriately increase the time for outdoor activities to improve physical fitness.
Nowadays, various flu vaccines are very common, and at present, vaccination is a very effective means of prevention, which can greatly reduce the risk of influenza infection, and can be given within a month before the flu season, and special antibodies can better help us eliminate the flu virus.
Moreover, after receiving the flu vaccine, even if you are accidentally infected with the flu virus, it can reduce the symptoms caused by the flu, but a flu vaccine can have a protective effect of about 6~8 months, so it is generally necessary to vaccinate once a year.
There is another point that many people are easy to ignore, the environment is also very important for the prevention of influenza, for example, the flu virus is relatively easy to multiply in a dry environment, which requires us to keep the respiratory tract moist, as well as indoor air circulation, here are two small ways to try:
One is to often open the window to ventilate the room, otherwise the long-term air circulation may lead to the reproduction of germs in the air, if it reaches a certain concentration is indeed easy to "hit", the second is to put a humidifier to increase the humidity in the room, keep the respiratory tract moist and not give the virus a chance.
The doctor has something to say
All in all, influenza A is not uncommon, but its harm is not small, pneumonia and respiratory distress syndrome caused by severe influenza A patients are fatal, especially for infants and young children whose bodies are still in the development period, so even if it sounds like an inconspicuous cold, we must take protective measures and not take it lightly.
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[4] Zhong Peili. Epidemic characteristics, influencing factors and model prediction of influenza in mainland China[D]. Guangzhou University of Traditional Chinese Medicine, 2020