Where does the flu come from in winter. Do you have the flu and then we die? What are the different types of flu

The diagnosis of influenza has long been familiar. The temperature rises, pouring from the nose, sore throat. There is nothing to be done, you have to sit at home for ten days, swallowing bitter pills and choking on milk with honey. But this is not fatal. Are you sure? Less than a hundred years ago, nearly 40 million people died from the flu epidemic. Doctors have such a sign: "If the cold has come, then the flu epidemic is not far off." All medical publications begin to publish articles on prevention and vaccination, and district doctors prepare a puffy stack of sick leaves. No wonder. Today, every year during epidemics of influenza, more than 15% of the entire population of the Earth gets sick.

Star epidemics

The first information about the flu dates back to 412 BC. It was then that the greatest physician of antiquity Hippocrates described a disease very similar to the flu. Patients had a sharp increase in temperature, head and muscles ached, and a sore throat appeared. At the same time, the main feature of the disease was incredible contagion. If at least one person became ill, after a couple of days dozens were sick, and after a week, hundreds of people. There was a real epidemic. The largest of them encompassed entire countries, and sometimes continents, and it is precisely such epidemics that were recorded in historical chronicles.

In the Middle Ages, outbreaks of flu were not uncommon; among the people they even came up with the special name “Italian fever”. Influenza patients were feverish due to high temperature, and many sinned on sunny Italy, suggesting that there is a source of infection. The state of medieval medicine left much to be desired: people sneezed, coughed, some died, and doctors could not help them. As a treatment, patients were prescribed only plentiful drinking, infusions of medicinal herbs and bee honey.

What is the reason for the appearance of mysterious epidemics? - thought doctors and philosophers. Some countries had their own explanations for this. In Italy, for example, it was believed that the special arrangement of stars and the moon was to blame. But pedantic Germans noticed that the disease comes in winter, and suggested that soaked apples and salted fish, the main “winter” food, are to blame. The general opinion was: "at all the will of God." It was believed that the epidemic is the punishment for sins, and you can only pray to God that the disease is bypassed. However, such prevention was not very effective.

In historical documents, references to major epidemics of influenza in 1510 and 1580 have been preserved. The latter made such an indelible impression on his contemporaries that it was recorded in detail in the annals. This is how the first strictly documented description of the flu epidemic came about. By the sixteenth century, the disease had already been described in detail, but still remained nameless. The disease received its first official name in the same century in Italy. They called him "influenza." There are several hypotheses regarding the origin of this word. According to one of them, scientists, desperate to find the cause of the disease on earth, began to look for it in heaven. Astrologers have suggested that the onset of the disease is due to the influence of stars. When the celestial bodies are arranged in a special sequence, an epidemic rages down on humanity. The word "influenza" in translation from Italian just means "influence, influence".

Another hypothesis of the origin of the name of the disease is not so poetic. When scientists noticed that epidemics occur in the cold months, they suggested that the cause is the effect of hypothermia. The word “influenza” also came in handy. Another official name for the disease - “flu” arose three centuries later. And if the name “influenza” is associated with the causes of the disease, then the word “flu” (from the French word “gripper” and the English “grip” - to grasp) indicates its symptoms. The disease begins suddenly and abruptly, a person literally in a few hours is as if seized by an ailment.

Chinese "Spanish"

Influenza epidemics occurred quite often, but the nature of the global disaster took three to four times a century. Such major epidemics are called pandemics. The pandemics of 1580, 1675, 1729, 1742-1743, 1780, 1831, 1857, 1874-1875 are known. For many centuries, scientists have accumulated a lot of information about the flu, but it was still very far from understanding its nature. Why does flu arise, why do epidemics occur once every 30 years, and how, in the end, is it treated?

Doctors continued to fight unsuccessfully over the cause of flu until 1889. Theories of influenza constellations and soaked apples have long outlived themselves, but new, more progressive ones have appeared. Scientists have tried to associate outbreaks of influenza with the pathogenic effect of the Earth's electric field, fluctuations in air temperature and changes in rainfall. Some experts pondered the effect of the amount of ozone in the air on the occurrence of epidemics. There was even a suspicion that influenza is an early stage of cholera.

Fantastic theories ended with the German physician Richard Pfeiffer. During the epidemic of 1889-1892, he isolated an extremely small bacterium similar to a stick from the sputum of patients. Was she causing the flu? The discovery of Pfeiffer was confirmed by studies by French and German scientists. The scientific world celebrated victory: finally, the cause of the flu is known, it’s a bacterium - Pfeiffer’s wand! However, antibiotics had not yet been invented, and there was nothing to treat the flu, as before.

The next flu epidemic occurred in 1918 at the end of World War I. Then no one suspected that this would be the worst pandemic in the history of mankind and it would take several times more lives than all military operations. The contagious, deadly flu has earned the special name of Spanish fever. It is ironic that, according to scientists, the birthplace of the "Spanish woman" was China. The first fatal cases of the disease were described by doctors in the United States in March 1918 and in the port cities of France, Spain and Italy in April 1918. Few knew of the Chinese origin of the flu, but it could very well be called "American" or "French." However, military censorship forbade all publications about the epidemic, so the first mention of it appeared in Spain, which did not participate in the war.

For ten months, the "Spaniard" has spread throughout the world. This was the first wave of the pandemic, followed by the second and third. In two years, 20 million people died from influenza, and according to some sources, this figure reached 40-50 million, that is, 2.5% of the world's population. The disease developed at lightning speed: in the morning the person was healthy, the temperature rose in the afternoon, and in the evening the doctor stated death. The one who was lucky to survive on the first day of the disease often died a little later from complications of the flu, such as pneumonia. According to statistics, almost a third of humanity has seriously suffered from the “Spanish woman”. In addition to high mortality, the disease had another feature: it mowed only the adult population. Old people and children, who were usually the main target of the flu, this time turned out to be invulnerable.

The Holy Trinity

The deadly "Spaniard" scared the doctors. If previously it was believed that a healthy body can cope with the flu itself, now the issue of prevention and the search for drugs has become a serious issue. Doctors have doubts about the bacterial nature of the flu. After all, if the same Pfifer stick caused the disease, why did the “Spaniard” differ so much from previous flu epidemics?

The answer to this question was found only in 1931. An American Richard Schope, studying the flu in pigs, discovered that the disease is not caused by a bacterium at all, but by a virus! Maybe viruses also cause human flu? This hypothesis broke all existing ideas about the causes of influenza, and some scientists took it with hostility. However, research continued, and two years later, the human influenza virus (Orthomixovirus influenzae) was discovered. In London in 1933, scientists at the National Institute for Medical Research, Wilson Smith, Christopher Andrews, and Patrick Laidlaw, first isolated the human influenza virus, which was called the "Type A influenza virus." The discovery story is quite funny. In 1933, an influenza epidemic occurred in England, and scientists, taking advantage of the situation, set a goal to find an animal sensitive to human flu. The experimenters infected all the animals that they managed to get, starting from snakes and ending with various rodents, and after a while they checked the health of their wards.

Time passed, and the animals were not going to hurt. Scientists were almost desperate and were ready to conclude that human flu was not transmitted to animals, when they were lucky. Walking around the vivarium again, they noticed that one of the ferrets looked unhealthy. When laboratory staff member Wilson Smith picked up the animal, the ferret sneezed. It turned out that the beast is sick, but with what? What was the surprise of the scientists when two days later Smith himself fell ill with the flu. This was the first case of experimental influenza infection in history, it was during this study that the causative agent of the disease, type A influenza virus, was isolated

It would seem that the causative agent was found, but in 1940 the scientific world was shocked by yet another discovery - Thomas Francis isolated another influenza virus, type B virus, and in 1947, Richard Taylor discovered the type C influenza virus. . Type A influenza virus most often leads to diseases of moderate or severe severity, and causes the disease not only in humans, but also in some animals: horses, pigs, ferrets, birds. All severe epidemics and pandemics are caused by this virus. Type B virus only infects humans, most often children, does not cause pandemics and usually causes local outbreaks and epidemics, sometimes covering one or more countries. Influenza C virus has been less studied than others. He only infects a person. Symptoms of the disease are usually very mild, or do not appear at all. Type C flu does not cause an epidemic and does not lead to serious consequences.

After it finally became clear that the causative agents of influenza are viruses, many mysterious facts from the history of the disease became possible to explain, for example, its variability and infectivity. But there are no less problems. How to find a cure for the flu? After all, a virus, unlike a bacterium, cannot be called a full-fledged organism; it is located, as it were, on the border of the living and nonliving, which means it is impossible to kill it. All that the virus has is a nucleic acid chain with genetic information and a protective coat. Only by invading other people's cells can a virus exist. With the help of special structures on its surface, it attaches to the host cell, and then penetrates inside, where it begins to dictate its own rules. Virus nucleic acids are embedded in the DNA of a healthy cell, and the affected cell, along with its proteins, begins to synthesize viruses in large numbers. Newborn viruses go free and look for a new owner, and their host cell is doomed to death.

The influenza virus acts on the same principle. Its target is cells lining the airways: mouth, nose, trachea. It is there that, after infection, by airborne or contact-household routes, viruses are introduced and viruses multiply there intensively. While a person is still feeling healthy, the so-called incubation period is underway. It lasts from 6-12 hours to 2 days. Then the toxic effect of the viral infection begins. A person suddenly gets sick. He may have a runny nose and sore throat. By this time, a great many viruses penetrate the bloodstream and spread throughout the body, acting primarily on the nervous system and brain. The patient begins to feel weakness, headaches, his temperature rises.

The next stage - viruses take over the entire body, affect the heart, brain and lungs, etc. All complications of influenza arise due to such a widespread infection, and also due to the fact that various pathogenic bacteria begin to attack a weakened body. Depending on the patient’s immunity, the flu can last from one to several weeks. During this time, the body's defenses will destroy all viruses and cope with the consequences of the disease. At first, this process is quite slow, and only when the immune system learns to recognize viral particles and begins to create special protection against them, the fight against the virus becomes more effective. Such flu immunity lasts for many years.

Elusive look

It would seem that once you have had the flu at least once, you can’t be afraid to pick it up, but this is where the insidiousness of the viruses appears. From year to year they change! Of course, their “content” remains almost unchanged: the flu does not cease to be flu. Only the surface of the virus is masked, but this is enough so that the immune system does not “recognize” it and the person becomes ill. These changes can be explained by the fact that moving from person to person, the virus undergoes mutations. Scientists called this process antigenic drift, during which antigens slightly change - substances from the surface of the virus.

The result of this drift is annual flu epidemics. They are rarely fatal, because people have partial immunity to a modified virus. The most terrible epidemics and pandemics happen once every 20-40 years, when a virus with such serious mutations that the immune system does not recognize it and where it comes from is unknown and the body is defenseless against the disease. The same mutations can give the virus additional properties, for example, an ultrafast course of the disease. Scientists call this change of virus antigenic shift. The most popular theory of antigenic shift says that the emergence of "evil" viruses is associated with mutations of the influenza virus during its transition from humans to animals and vice versa.

Question: “Where does the flu virus come from and where does it hide between epidemics?” many researchers asked themselves. The only thing they managed to establish: the virus circulates from the Southern Hemisphere to the Northern and vice versa. In the autumn-winter months it is in the north, in the spring-summer months in the south. And throughout the year, outbreaks of flu occur in the equator area. Perhaps there is the birthplace of influenza.

Some scientists suggest that in the interval between epidemics, the virus is dormant in the organisms of birds and animals. These are only hypotheses; there is no reliable evidence yet. Despite the fact that already in the 1940s the first vaccines appeared that instilled human immunity to the influenza virus, scientists could not invent a cure for the disease. The history of influenza pandemics continued. 1957-1958 - Asian Flu came from the Far East. Only in the USA, 70 thousand people died from him. 1968-1969 - "Hong Kong flu", elderly and children suffer. The death toll is almost 34 thousand people. 1977-1978 - Russian Flu, relatively mild.

By now, nearly thirty years have passed since the last flu pandemic, and apparently the next one is just around the corner. Doctors around the world are in suspense and constant alert. We can only inject the flu vaccine on time, hoping that scientists from WHO correctly guessed the strain of the upcoming virus. Stock up in case of remantadine. Raise immunity with interferon and vitamins. And hope that already in the XXI century, a cure for the flu will certainly be invented.

Influenza is a serious infectious disease that can affect people of any age and gender. According to statistics, every year millions of people around the world die from influenza and its complications. Thus, the flu poses a serious danger to life and health. Therefore, it is very important to know what the main symptoms of the flu look like.

Description of the disease

Influenza has been known for a very long time, since ancient times. However, it became a serious problem only in the twentieth century, as the most terrible bacterial infections - the plague, cholera, and typhoid - receded. The pandemic of the “Spanish flu”, which took place at the beginning of the twentieth century and affected almost all countries and continents, is well known. Then, tens of millions of people died from the disease, many of whom were young and healthy. Often even today in certain regions there are outbreaks of new dangerous varieties of the disease, such as swine or bird flu.

However, epidemics of common flu, sometimes called seasonal flu, can be dangerous. In seasonal flu, the disease affects many children, the elderly and people with chronic diseases and other health problems. Flu is also dangerous for pregnant women, as it can harm the health of the child.

It is also worth considering that the disease causes great damage to the economy of any country that is undergoing an epidemic, since a significant part of the working population is unable to work for a certain period of time. In general, seasonal flu during the year can get up to 15% of the world's population. And about 0.3% of diseases result in death.

How does the flu

The disease is caused by tiny biological particles - viruses. Influenza virus was isolated in the mid-20th century. It belongs to the group of RNA-containing viruses, that is, viruses that store genetic information in the RNA molecule. In total, three types of the virus are known - A, B and C, inside which virologists isolate individual strains and serotypes, depending on which proteins the influenza virus contains.

A characteristic feature of the influenza virus is its ability to mutate constantly. This means that every year new strains appear, and if a person has had the flu and has become resistant to infection with one strain, this does not mean that next year he will not be able to catch the disease caused by another strain of the virus.

The most severe influenza epidemics are caused by viruses of the genus A. They can be transmitted both from person to person, and from animals to people. Viruses of the genus Less commonly cause epidemics, although among viruses of this group there are also those that cause severe forms of the disease. The genus C flu virus never causes an epidemic. This is a relatively safe type of virus for humans. It affects only the most weakened categories of people.

Influenza virus is usually quite resistant to adverse external influences. It can be stored frozen for up to several years. At room temperature on various objects, it can be stored for several hours. Drying and heating to +70 ºС kills the virus in a few minutes, and boiling does it almost instantly. The virus is also sensitive to ultraviolet light, ozone and certain chemicals.

In most cases, the virus is transmitted by airborne droplets, by sneezing or coughing, in some cases even during normal conversation. Infection can also occur through household items, for example, when a person touches the surface of objects with the virus on his hands, and then the face. When it enters the mucous membranes of the respiratory tract, the virus begins to multiply.

The incubation period of influenza depends on various factors - the number of viral particles that enter the body, the state of the human immune system, such as a virus, etc., and can vary from several hours to 5 days.

A person who has become infected with the virus can be dangerous for others, because it spreads pathogens around itself. This danger persists even if a person has not yet become ill or has already had the flu. However, the most dangerous person with influenza in the first two days of the disease.

Forms of the disease

There are several main forms of the disease, depending on the intensity of the symptoms observed:

• light
• average
• heavy
• toxic
• lightning fast.

For mild to moderate forms of influenza, treatment can be done at home. In other cases, hospitalization is recommended. This is especially true for people with chronic diseases of the cardiovascular system and lungs.

Flu Complications

Most fatal cases with influenza are associated not with the disease itself, but with its characteristic complications. Complications of influenza affect primarily the cardiovascular and nervous systems, lungs, kidneys and liver. The most dangerous flu complications are:

• viral pneumonia that is difficult to treat even in a hospital setting;
• inflammation of the heart muscle - myocarditis and the tissues surrounding the heart - pericarditis;
• inflammation of the meninges () and the brain (encephalitis);
• severe renal and hepatic insufficiency;
• early termination of pregnancy and fetal infection in pregnant women.

Symptoms

The symptoms of flu are extremely diverse. The main symptoms include:

• high temperature
• cough,
• headaches,
• body and muscle pains
• sore throat
• eye pain
• runny nose (rhinitis),
• weakness and weakness
• gastrointestinal disorders

All these symptoms, with the exception of fever, may not always occur and not in all patients.

Heat

This symptom is characterized by high values. Typical temperature at the onset of the disease, as a rule, is above +39 ºС, and often can exceed the mark of +40 ºС. Only with mild forms of influenza, the temperature can fluctuate at a mark of +38 ºС. Such a strong increase in temperature is the result of intoxication of the body, as well as the reaction of the immune system to it.

Another feature of temperature increase is that it usually occurs very abruptly, literally in a few hours. The duration of the period during which the patient's temperature is elevated depends on the severity of the disease and on whether the patient is taking antipyretic drugs. It usually lasts 2-4 days. Then the temperature drops to subfebrile values. In the case of severe forms of influenza, fever does not go well with antipyretic drugs. Or it gets off for a very short period of time.

Cough

Influenza viruses mainly affect the mucous membrane of the bronchi. Therefore, with flu, coughing is also a typical symptom that appears in 9 out of 10 patients. However, coughing is far from always evident in the first hours of the disease. In addition, coughing can often be relatively mild compared to coughing observed with other respiratory diseases. The cough is usually continuous, it can plague a person and prevent him from falling asleep.

At the onset of the disease, the cough is usually dry and unproductive. As the sputum leaves, the cough changes to wet.

Pain in the head and body

Headaches, chest pains, as well as vague pains in other parts of the body, especially in the muscles of the legs, are the result of intoxication of the body. Often these are the first flu symptoms that appear even before the temperature rises. Pain in the muscles can be in the nature of aches. Headache usually concentrates in the frontal zone, although it can spread throughout the head. Sometimes there may be pain in the eyes, photophobia. All these are quite common flu symptoms.

Laryngitis, pharyngitis, runny nose, sinusitis

Symptoms of inflammation of the mucous membranes of the upper respiratory tract - a runny nose, sore throat, sneezing can often not be observed at all. However, such symptoms also occur (in about half the cases). Often they are explained not by exposure to the influenza viruses themselves, but by a secondary bacterial infection. Most often, children suffer from such phenomena.

Other symptoms

Sometimes there are violations of the gastrointestinal tract - nausea, dyspepsia, loss of appetite. Vomiting and diarrhea are sometimes possible. Although in general for flu, such symptoms are uncharacteristic.

Also, against the background of high temperature, the patient may experience increased sweating, redness and hyperemia of the skin, heart palpitations, low blood pressure, and heart rhythm disturbances. When listening to the heart, muffled tones, systolic murmur are noticeable.

Disease duration

The active phase of the flu with distinct symptoms usually lasts no more than 3-5 days. A longer course of the disease increases the risk of various complications - pneumonia and pleura, otitis media, myocarditis, endocarditis, encephalitis, liver and kidney damage.

What are the different types of flu

With a mild form of influenza, the patient has a relatively low temperature - in the region of +38 ºС, and sometimes subfebrile, cough is weak or may be absent. Overall health is satisfactory. The active phase of the disease lasts 2-4 days, and a full recovery occurs after a week.

When the disease is moderate, a temperature of about +39 ºС is observed. The cough is moderate. The patient's condition is satisfactory, despite a strong weakness. Headaches may be present. In severe influenza, the temperature rises to +40 ºС. Severe headaches and aches throughout the body. Severe cough, nosebleeds are possible. If the temperature rises above +40 ºС, convulsions, delusions, hallucinations, and loss of consciousness are possible.

The fulminant form is a rare form of flu, but this is no less dangerous. It is characterized by a very rapid development of symptoms, fever up to +40 ºС, within a few hours, the presence of signs of general intoxication of the body. The disease can result in pulmonary and brain edema and death.

What to do with the first symptoms?

In the event that a person has the first signs of flu, then the first thing to do is to call a doctor at home. The main reason for calling a doctor is a high temperature - over +38 ºС. Going alone to a clinic with such a temperature is dangerous not only for the patient himself, but also for those around him whom the patient can infect. Especially vulnerable to infection are children and the elderly, people suffering from cardiovascular diseases and kidney diseases. However, even adults and healthy people can die from toxic flu. Such a development of events is completely possible.

Before the arrival of the doctor, bed rest must be observed. It is better not to take antipyretic and anti-inflammatory drugs if the patient's condition is satisfactory, since their intake can distort the clinical picture. The doctor should examine the patient and decide whether he should be treated at home, or in a hospital. If treatment is carried out at home, the doctor will prescribe all the necessary medicines.

For the treatment of influenza can be used:

• etiotropic drugs
• immunomodulators
• symptomatic agents (anti-inflammatory and antipyretic drugs).

For the treatment of cough, expectorant and mucolytic drugs are taken. Rinses, inhalations, nasal preparations are useful for treating a throat and a runny nose.

Of great importance for a speedy recovery are also a proper diet, the use of vitamins, heavy drinking, and bed rest.

What is the difference between influenza and SARS

Influenza is a less common disease than a common cold. But at the same time more dangerous. In everyday life, flu is often called any ARI, accompanied by an increase in temperature. But this is completely wrong. Various bacteria and viruses can attack the body, including the respiratory tract, but flu is only a disease caused by the flu virus, and no other.

The viruses that cause the so-called acute respiratory viral diseases (ARVI) include:

• rhinoviruses
• adenoviruses
• enteroviruses
• parainfluenza viruses.

The likelihood of catching a disease caused by any of this virus is much higher than getting the flu. Moreover, a single person can not get the flu every year, while he can tolerate respiratory diseases caused by other viruses every year.

This situation gives rise to a somewhat condescending attitude towards the disease. Say, last winter I was sick with the flu - I sneezed, coughed, took a few days, so what’s wrong, I didn’t die! So why do we need vaccinations and other measures to prevent influenza? Meanwhile, this person might not even encounter the flu virus as such.

Most people who are faced with the flu, and not with SARS, can distinguish flu symptoms from SARS symptoms. However, in some cases this can be difficult. Viruses such as the parainfluenza virus, which is reflected in its name, can give symptoms very similar to those of mild to moderate flu. Therefore, it is by no means superfluous to recall which symptoms themselves are more characteristic of influenza than SARS.

Firstly, it is a sharp rise in temperature to high values, at + 39-40 ºС, over a short period of time, literally in a few hours. In most other respiratory diseases, the temperature rises much more slowly, that is, a person feels subfebrile for half a day or one day, and it rises to + 38ºС or even + 39ºС only the next day. This feature of the disease is very dangerous, because often a fever can catch a person by surprise, for example, when he is at work.

Secondly, it is the temperature level itself. With most acute respiratory viral infections, the temperature still does not exceed the +39 ºС mark. With influenza +39 ºС, this is by no means the limit. Often the temperature can jump to +40 ºС. However, with some other infectious diseases, such a high temperature is also possible, for example, with enterovirus infection. However, it is more common in the summer.

Thirdly, this is the time of the onset of respiratory symptoms, such as coughing. With flu, symptoms of this type usually appear only after a fever. With acute respiratory viral infections, a person may have a sore throat all day, and only after that there will be an increase in temperature.

Fourth, this is the severity and amount of the respiratory symptoms themselves. With real flu, the patient usually suffers only a cough, which, however, can be very strong, and chest congestion. Pharyngitis, laryngitis and rhinitis are rare. They are usually associated with a later bacterial infection.

Fifth, these are common signs of intoxication - headache and aches throughout the body, especially in the muscles of the legs. For ARVI, such symptoms, as a rule, are not characteristic, in contrast to the flu. Also, importantly, such flu symptoms can appear even before the temperature rises and the appearance of respiratory symptoms, and, thus, are the very first signs of an impending disease. Symptoms such as severe malaise, fatigue and weakness are also not characteristic of SARS.

Sixth, this is the duration of the disease and the recovery period. With SARS, the temperature usually lasts 2-3 days, and after a drop in temperature, a person usually feels good. With influenza, the temperature lasts 4-5 days, but even after the fever has passed, a person can feel overwhelmed and unwell for a couple of weeks.

Throughout the world, respiratory infections in the autumn-winter period account for up to 95% of cases of morbidity. And most often, SARS is caused by the influenza virus. But what is it - a virus, where did it come from and why is it dangerous?

What is a virus?

Any virus is a microscopic particle consisting of proteins of a different kind, each of which performs a specific function. It consists of:

• Chains of DNA or RNA that contain all the genetic information necessary for the reproduction of a new particle.
• Protein protective shell, which retains it under adverse conditions.
• Special protein molecules that are on the shell and help to recognize body cells and attach to their surface.

Viruses can infect any organisms, including plants, insects, and even bacteria. To date, scientists know about six thousand different species of this pathogen, but in fact there are many more.

Basic properties

Unlike other sources of infectious diseases, such as bacteria, viruses have completely different properties:

• They cannot actively exist and multiply outside the cell, since they do not have their own energy and protein synthesizing systems. They borrow all this from an infected cell, literally making it work for itself.
• They have a durable shell that protects them from the negative effects of the external environment. Therefore, while outside the cell, pathogens are able to withstand heating or cooling to extreme temperatures.
• They are not able to grow, but multiply only by reproducing a new particle from their own genetic material.

Thanks to a rather simple structure, the virus is able to penetrate any living cell, having passed all the protective systems of the body.

Bypassing the cell membrane of its nucleus, with the genetic information contained in it, it is introduced into the nucleus of the host cell and completely rebuilds its work. As a result, the cell itself begins to synthesize new particles of the pathogen, which, after its death, spread throughout the body and infect new cells.

Origin

Viruses have been known to mankind for more than one millennium. The same flu was first described by Hippocrates as early as 412 BC. True, it was the viral nature of this disease that was discovered not by the ancient scientist, but by the American R. Schope in 1931.

As for its origin, then the opinions of scientists were divided. To date, there are three versions of this event:

• The theory of evolution, according to which all viruses and influenza including, occurred due to the fact that part of unicellular organisms began to develop in the opposite direction.
• The theory of co-evolution or joint evolution, according to which these pathogens developed simultaneously with the first living cells on Earth, only their development followed a slightly different path.
• A theory of cellular origin, which claims that they were formed from the remains of the genetic chains of DNA or RNA, which were released from the genome of another organism as unnecessary.

Unfortunately, each of the existing theories of occurrence has its weaknesses and it has not yet been possible to determine exactly where the first viruses came from.

However, there is an answer to the question of where viruses dangerous to humans come from. They, as a rule, appear as a result of mutations of pathogens that previously only affected animals or birds. So, in 2003, the SARS virus appeared, which causes SARS and which just passed to humans from animals.

Many factors can lead to mutations and the spread of viruses, but the main ones are:

• Constant population growth of the planet.
• Increased ability to travel to other countries and even to other continents.
• The development of commercial and industrial relations, due to which pathogens can fly across the ocean, for example, with the supply of fruits, vegetables or meat.
• Development and creation of new antiviral agents that can also cause changes in the microparticles of the pathogen and lead to the appearance of other species.
• The development and development of regions with wildlife, in each of which they can live their own special microorganisms, not yet known to humans and capable of causing infectious diseases.

Viruses are volatile and can reproduce themselves at a fantastic speed. Up to 100 million viral particles can form from one infected human cell. To date, the most effective method of combating this pathogen is vaccination.

Seasonal flu comes in late winter - early spring. The virus is dangerous for the elderly, people with severe concomitant pathology and young children. In addition, every 10-15 years there are epidemics of atypical disease, which has a high mortality rate.

Why are doctors around the world still so afraid of the flu? In this article we will tell about the history of the virus, the symptoms of the disease, the features of its course in various population groups.

Virus history

Mankind has faced epidemic infections a long time ago. For example, Hippocrates also describes symptoms similar to flu. Annals recorded only abnormal cases of morbidity that claimed many lives. In the Middle Ages, scientists talked about "Italian" fever, in which patients suffered from high fever, joint pain. Many did not survive, and doctors of those times were powerless before the mass spread of the infection.

Already in the 20th century, a type of virus called Spanish flu significantly reduced the world's population. At the same time, China becomes the "homeland" of the epidemic. In Europe, the infection gets on the ships of sailors. The coastal ports of Spain, France and Italy will become a place of mass deaths. From here, the flu virus spreads throughout Europe. Asia and the USA will suffer greatly from it.

"Spain" is considered one of the worst epidemics. The flu virus kills at lightning speed. If the patient had the first symptoms in the morning, then in the evening, doctors could ascertain his death. Another feature of the Spanish virus will be that sick people are basically a young able-bodied population. Old people and children who are more likely to be affected by this infection have remained safe here.

Clinical picture

Everyone should know the flu symptoms. This infection is significantly different from SARS. Treatment of the virus must necessarily take place under the supervision of a physician. Otherwise, complications after the flu will lead to serious health consequences. Below we describe the clinical picture of the disease.

Signs of flu appear acutely, against the background of full health. The patient, as a rule, can name not only the day the onset of the disease, but also the hour. The first signs of influenza are an increase in temperature to high numbers (38 and above), aches in the muscles and joints. Ordinary ARI does not have such a picture. Symptoms of a cold, as a rule, increase gradually. Also, with this disease, there is severe chills.

Damage to the nervous system is manifested by signs of severe intoxication and headache. Head aches from harsh sounds, light and movement. The pain is localized in the frontal region, around the eyes, above the eyebrows. Symptoms of influenza are characterized by the fact that vomiting does not appear against the background of pain. In the presence of such severe signs, meningeal infection must be excluded.

Catarrhal symptoms are mild. A runny nose is almost absent at the onset of the disease. Sore throat is not expressed. But there is a dry nagging cough, which occurs on the 2-3rd day of the infection. Influenza virus has high vascular tropism. Therefore, red eyes and nosebleeds often occur in sick people.

The disease is accompanied by a long recovery period. If the patient is sick acutely for more than 7-10 days, then the next 2-3 weeks the patient has increased fatigue, sweating, reduced exercise tolerance. Such an asthenic syndrome never happens with acute respiratory viral infections.

Features of influenza in children

The child is difficult to tolerate this virus. Influenza in children often has a severe course and is accompanied by the development of complications. Fever in this infection is often accompanied by confusion, the appearance of febrile seizures. Influenza in children can be accompanied by increased moodiness and irritability of the child. But a critical condition is a loss of interest in the outside world, apathy, and a decrease in activity.

Influenza in children is difficult and prolonged. Be sure to carry out treatment under the supervision of a doctor. If necessary, the baby is hospitalized in a hospital.

Hospital treatment is required with:

• severe and moderate infection;
• with a fever that does not stop with antipyretic drugs;
• with a "barking" cough in a child, the appearance of shortness of breath, cyanosis of the face;
• refusal to drink.

Features of influenza in the elderly

After 65 years, a person accumulates a load of chronic infections. That is why an infection like the flu is very difficult in the elderly. As a rule, patients go to numerous complications of the disease:

• influenza or bacterial pneumonia;
• neurological complications;
• worsening heart activity;
• activation of chronic infection.

Doctors advise older people to get immunized. A flu shot can prevent the disease. Also, vaccination will make it easier to transfer the virus. Indeed, most often cases of complicated course and fatal outcomes from influenza are recorded in this particular population group.

Influenza during pregnancy also needs careful monitoring by specialists. Women “in position” should not use certain types of drugs. Also, infection can adversely affect fetal development. In addition, the strain of "swine" flu, which recently circulated in Europe and the European part of Russia, had a high mortality rate in this particular population.

Disease therapy

Flu treatment became more effective in the 21st century. This is due to the fact that preparations have recently been invented to inhibit the reproduction of the virus. Unlike the drugs used earlier, these drugs showed high efficiency in the fight against influenza A. In addition, the drugs are quite safe, which allows them to be widely used in both adult and pediatric practice. In the epidemic of “swine” flu, the drug Oseltamivir (trade name Tamiflu) showed itself well. It improves the course of the disease at an early start. In addition, Tamiflu is effective in treating the complications of influenza - viral pneumonia. Tamiflu is allowed to be used only after consulting a doctor and establishing a diagnosis of influenza. Irrational use of the drug can cause negative consequences for the body.

Tamiflu can be used in pediatrics. The instruction for the drug says that in the form of a powder it is allowed to be used in children older than 1 year. However, the pediatrician selects the dosage. In addition, contraindications to taking this substance are possible.

The second etiotropic agent is the substance Zanamivir (trade name Relenza). The medicine is available in the form of a powder for inhalation. Also included in the package is a special device for delivering powder to the lungs (discoaler). It allows you to conveniently dose Relenza and avoid overdose. This type of etiotropic treatment is used in pediatrics (in children over 5 years old) and in adults.

Concomitant therapy is bed rest and drinking. The fever needs to “run over”. During illness, you need to drink 2.5-3 liters of fluid daily. This may be a weak tea, fruit drinks, unsweetened dried fruit compotes. At temperatures exceeding 38.5 ⁰ it is necessary to take an antipyretic. With this virus, paracetamol and ibuprofen are allowed. But acetylsalicylic acid can not be taken. It can provoke Reye's syndrome (acute liver failure).