Isn't cholera a category A infectious disease? Why is it dangerous?

It is also cholera. Some strains may be a "intestinal laxative", while some strains can "suck millions of powder". It is hot in summer and high temperatures. Pay attention to hydration and prevent diarrhea is what we really should pay attention to.

Written article | Li Qingchao (Shandong Normal University)

At the beginning of this week, a student in Wuhan University had infectious diarrhea and diagnosed as cholera. The choice is the "king of the stomach". The handle of the diarrhea world is one of the only A -type infectious diseases in my country's statutory infectious diseases (the other is an plague). This kind of acute diarrhea may cause death within a few hours if not treated.

Since the 19th century has spread from the Ganges Delta in India to all parts of the world, cholera has killed millions of people. At present, there are about 1.3 million to 4 million people in the world's infections worldwide, causing 21,000 to 143,000 people to die [1].

Figure 1: The plague is also called black death, and cholera is also called blue death. Patients with cholera are gray blue due to severe dehydration. [2]

The cholera is so terrible, why is the official response so calm, and the dormitory sealing control was lifted on July 12th [3]. Isn't it afraid that the outbreak is popular? This starts with cholera.

Looking for chaos -the discovery of choleraja

As early as the fifth century BC, there were cholera records in Sanskrit. In history, people are often shrouded in the fear of this plague, but they know little about the cause of cholera. Until the middle of the nineteenth century, during the third global cholera, people also thought that cholera was caused by "radon" -ly bad air -.

Now it seems that this theory is of course incorrect, but it is much stronger than the interpretation of "evil spirits". The first historic breakthrough in cholera was proposed by British doctor John Snow (1813-1858). After a detailed investigation of the choice epidemic in London, England, Snow locked the source of cholera to the water source.

Figure 2: Maps used in John Snow and its investigation in 1854. The black thick line on the right indicates cholera cases, and these cases are concentrated near a pumping machine. Source: wikipedia

Snow's research confirms that the popularity of cholera is caused by pollution; subsequent research found that cholera is a kind of dung transmission disease, and this discovery provides the theoretical basis for how to prevent cholera. Snow's research can be said to be a major event in the history of public health, and it has also created a precedent for epidemiological research. (For details, see "He used mathematics to predict the origin of epidemic disease, and finally recognized after 30 years of injustice")

What is the pathogen of cholera? Almost in the contemporary contemporary contemporary contempora on Snow's epidemiological survey, the Italian doctor Filippo Pacini (1812-1883) conducted a corpse inspection of the cholera dead, and found many comma-like bacteria in the feces and intestinal mucosa. Essence But Pasini failed to separate this bacteria successfully, nor did it prove the relationship between this new bacteria and cholera.

Thirty years later, in the 1880s, German biologist Robert Koch (1843-1901) also discovered this kind of comma-like bacteria while studying cholera, and obtained the pure culture of this bacteria (only Contains a medium of microorganisms). Koch believes that this is the pathogen that leads to cholera. However, infected with such bacteria -like bacteria, it does not cause cholera -like diseases. He has proved that the efforts of bacteria and diseases have failed through the "Koch Law" he created!

Later, it was speculated that this may be because the experimental animals used at the time had already immune to such amazing bacteria.

Figure 3: The discoverer of Vibrio Cholerae Felipo Pasini (left) and Corch (middle). The former was more than 30 years earlier than the latter, and the name of the "Joined Pepsi" was based on the name of the former. Huroe (right) is like a comma with a long tail. Source: wikipedia

Joined Kye is a highly sporty comma -shaped Gram -negative bacteria, 1.3 microns long, 0.3 microns in diameter, and the average travel speed reaches 75.4 microns/second Mi (calculated according to the length ratio).

Choib is caused by cholera. But in fact, most of the infected people of cholera are asymptomatic or only mild symptoms. Only O1 and O139 two serum -type cholera can cause a large -scale epidemic. Therefore, you don't need to see the word "cholera" and panic, but it depends on the toxic power of the germs.

Notice on the disposal of a cholera case in Wuhan University

Huroir toxins -the big kill of terrorists

The so -called virrence refers to the ability, or pathogenic force that causes damage to the host. Bacteria can be adhesive (combined with host or cell surface), fixed colonization (breeding in specific locations), invading (entering the body or cell), immunosuppressive (inhibiting the clearance of the host immune system) and toxins (toxic substances) (toxic substances) The ones are ill.

Figure 4: Bacteria causes the basic process of host disease. Any factors that are conducive to the completion of the above process can be called a toxic force factor. [4]

Severe, deadly cholera cases of liquid-liquid "rice"-like feces during diarrhea, and the cholera patients who have not been treated may produce 10-20 liters of rice-like feces every day. At this speed, a 80 -kg man will be dried in four or five days. What makes the cholera with high pathogenicity is so toxic? Figure 5: It is also cholera. Some strains may be a "intestinal laxative", while some strains can "suck millions of powder". Picture Source | The cover of the 1912 French magazine "Le Petti Journal".

This problem was not solved by Indian scientists Sambhu Nath de (1915-1985) in the middle of the 20th century: he discovered cholera toxin (CTX). Sanbu Nat De uses a bonus ligation of rabbits to establish animal models to study diarrhea. In short, it is to find a long sausage on the rabbit that fasts and emitting the intestine, and then use several ileum to ligate the sausage. Injecting in the intestinal section may cause diarrhea bacteria. If this bacteria can cause diarrhea, the intestinal wall will release large amounts of liquid to the back intestinal cavity; these liquids will accumulate in the corresponding recovery section due to the barrier of the intestinal ring. In this way, the ability of bacteria can cause diarrhea through a comparative effusion. In addition, he injected the upper clearing of choleramine culture (liquid after removing the bacteria) into the rabbit's intestinal ligation model. As a result, it was found that the liquid that did not have cholera can also cause severe diarrhea.

This experiment has proved that cholera bacteria can release a certain substance, which leads to severe diarrhea. This substance is cholera toxin (CTX). Later research proves that cholera toxins are protein. People use cholera toxins as antigens and make vaccines to prevent cholera. The application of cholera to toxins also proves that the main toxic factors of the cholera are cholera toxins. As long as it can neutralize cholera toxins, Jooth Caiser is difficult to cause serious diseases.

Figure 6: Hindu scientist Sanbnard and the cholera toxin structure later parsed

Hoothy toxin is a kind of hexagonal body, which is composed of a Azyme subunit and five B receptors. It can be written as AB5. Part A is "the biggest chaos", and B is the role of A entered the cell as "leading wolves into the room". The receptor binding to the subtype of the human intestine cell surface components (mainly the ganglide, other glycogen can also be used, and other polysaccharides can also be) pry open the door to the cell. Once the cholera toxins enter the cells, enzyme A sub -A can make trouble. Popularly speaking, enzyme sub -ames can increase the level of signal molecularly at a steady -state signal molecular level in the cell (by combining ARF6 to finally continue to work on adenosanate cycle enzymes, generating a large amount of CAMP) Unrestrained "open locks and putting chlorine" (stimulated by the CAMP signaling pathway, the chloride ion channel CFTR is abnormally activated). The normal ion level differences in the cell membrane were broken. While excessive polychloride was released outside the cell, the water, potassium and sodium ions were forced to secrete the intestine, causing a large amount of loss of water and inorganic salt ions. In a word, the cholera toxins can slip into the intestinal cells, open the valve, and make people fall thousands of miles and lose their souls.

Ironics is that cholera bacteria can get the blessing of cholera toxins, not because of the favor of God, but because they are "sick". It is found that the coding gene of the cholera toxin CTX does not belong to the cholera, but a phage CTX φ. You know, phage is a natural enemy of bacteria.

The CTX φ phage was first discovered in 1996. It is a soluble original single -chain DNA phage that can infect Joothye. The so -called soluble originality means that after the bacteria infected with bacteria does not cause bacteria to crack, but instead enter a state of carrying a phage. In this way, cholera bacteria have obtained the coding gene of cholera toxins. This is really a proper "no gun and no gun enemy to make us." What's more, the choleraja cargion carrying phage can also release the phage, allowing other cholera bacteria to infect the phage, and obtain the ability to produce cholera toxins. The choice infected with CTX φ phage is like a terrorist who got the big killing device. The combat effectiveness instantly burst into the table, and the person infected with the cholera bacteria carrying the CTX φ phage suffered.

Figure 7: CTX φ phage infection with cholera bacteria, and makes cholera bacteria have the ability to secrete cholera toxins. Hoothye (upper left) with high toxicity (upper left), after infection with CTX φ phage (red thread in the upper left circle), obtains the CTX gene, which can express the cholera toxins (bottom left) and have higher infection and pathogenic ability. [5]

Speaking of which, everyone should understand that although the cholera virus infected by Wuhan University is a serum type that can cause a large -scale epidemic, it does not carry the cholera toxins. Therefore limited. What should be worthy of our attention is the symptoms of diarrhea itself.

Good guys are defeated by three bubbles

What are you afraid of? Good Han is afraid of one text money, double fist, three bubbles and four -handed. The third child is "thin", also known as diarrhea, is a very common condition. There are about 17 to 5 billion diarrhea every year in the world [6], which is particularly common in developing countries. Diarrhea is not a trivial matter, and 1.6 million people die every year due to severe diarrhea (2017 data) [7]. The good Han was still defeated, and the child could not bear it naturally. Diarrhea is the enemy of infants and young children, and is the second leading cause of the death of children in the world. It causes death of children over 500,000 or less than 500,000. [8] Strict diarrhea definition refers to the condition of at least three liquids or water stools a day (babies feeded by pure breast milk or milk powder are loose and not forming, but without water, it is normal). According to different clinical symptoms, it can be divided into three categories: Among them, water -like diarrhea that lasts for several hours or days is called acute water diarrhea, such as cholera; acute diarrhea with blood is called acute blood diarrhea, also known as dysentery; Or longer diarrhea is called persistent diarrhea. The main cause of diarrhea caused by hazards is that the electrolyte imbalance and dehydration caused by a large amount of water loss in the short term are very dangerous; the problem with chronic diarrhea is mainly nutritional loss, which can cause malnutrition and slow development.

TIPS: dehydration

Dehydration is a condition for excessive loss of water in the human body. The human body can tolerate 3-5%of water loss (mild dehydration), but more than 5%will cause fatigue and dizziness (moderate dehydration). More than 10%will cause serious discomfort (severe dehydration ), More than 15%-25%of water loss is life-threatening [9]. There are many reasons for dehydration, such as hot weather, excessive exercise, causing sweating dehydration, vomiting, diarrhea causes loss of body fluids and dehydration, diuretics, drug effects, and disease effects cause dehydration. The signs of dehydration include headaches, fatigue, general discomfort, irritability, less urine, etc. When severe dehydration, the eyes of the eyes, tears without tears, skin rebound deterioration, and even loss of consciousness.

Figure 8: The performance of baby dehydration. Babies are often dehydrated due to diarrhea. The above conditions occur and need to be replenished or treated in time. [10]

After a large amount of sweating, vomiting, or diarrhea, you should drink water in time after the occurrence of moisture loss. In severe cases, you should take the electrolyte supplement or intravenous infusion supplementary body fluid. In particular, I should remind my elderly friends that the feeling of thirst after the increase of age becomes weakened, and the habit of drinking water without feeling thirst should be developed.

Figure 9: Determine whether the body is short of water according to the color of the urine. [11]

There are many causes of diarrhea. The main factors are the following:

Infect. Viruses, bacterial or parasitic infections can cause diarrhea, and diarrhea caused by infection is called gastroenteritis. Among them, the most common pathogens of viral diarrhea are rotatoral virus, adenovirus, and Noro virus. Common bacterial diarrhea primary primary primers mainly include cholera, Hedoge, Salmonella, and pathogenic E. coli. The risk factors of diarrhea infection are unclean foods and water sources, public health conditions, and poor personal hygiene habits.

Poor nutrition. Successive nutrition is very important for prevention of health and disease, especially in infants and young children who have not yet developed the immune system. Under the condition of malnutrition, the human immune system is blocked, the disease resistance is low, and the diarrhea is susceptible to infection, and diarrhea causes nutritional loss, which will form a vicious circle. Among them, zinc and vitamin A deficiency is closely related to the frequent occurrence of diarrhea.

Economic backwardness is an important source of the above reasons. The deaths caused by diarrhea mainly appeared in the underdeveloped economy, South Africa, South Asia, Southeast Asia and other places. The incidence and mortality of diarrhea can be reduced through the improvement of sanitary conditions and nutritional conditions brought by the development of socioeconomic and economic development.

After the founding of the People's Republic of China, the prevention and control of cholera is effective. There is no need to panic in this choice case. Pay attention to the hygiene of diet and drinking, and pay attention to hydration (especially in the current high -temperature weather), which we should remember in our hearts.

Summarize:

There are many serum types of cholera, and only O1 and O139 may cause great popularity. Joined vylobus with cholera toxins can cause fatal diarrhea. The reason why diarrhea is dangerous is that severe diarrhea can cause fatal dehydration. Judging dehydration and timely replenishment can greatly reduce the life threat caused by diarrhea.

references

[1] https://www.who.int/zh/news-load/fact-detail/Chlorara

[2] The site rose: Disease and the Art of Medical Illustration, by Richard Barnetttttttt

[3] http://news.hnr.cn/shxw/article/1/15469959400223234

[4] https://en.wikipedia.org/wiki/dehydration

[5] https://microbewiki.Kenyon.edu/index.php/ctx%CFPPPPPPPPPHGE

[6] https://en.wikipedia.org/wiki/diarrhea

[7] https:/mrworldindAta.org/diarrheal-diseases [8] https://www.who.int/news/fact-rheets/diarrhoeal-disease

[9] https://medical-dical.thefreedictary.com/dehydration

[10] Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. 2003

[11] https://en.wikipedia.org/wiki/dehydration

Produced: Popular Science China-Starry Sky Plan

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