Influenza type in symptoms. What is group C (B) flu

Influenza is a viral acute illnessaffecting the lower and upper respiratory tract. The disease begins with severe intoxication, which can cause complications and even death, in particular in children and elderly adults.

Influenza is a type of ARVI. It is worth noting that all acute respiratory viral infections are similar in symptoms and mode of infection.

However, only with the flu does severe intoxication appear, so the disease is generally difficult, which causes various complications.

To know everything about influenza and understand what influenza A and B are, to distinguish between the symptoms of influenza, you need to understand its structure, which consists of an RNA-containing virus, and also understand what the symptoms of influenza are .. Influenza viruses have internal and surface antigens ...

NP - internal antigens that make up the capsid and M, which is a layer of membrane and matrix proteins. NP and M are type-specific agents, so the synthesized antibodies do not particularly have a protective function. On the outside of these structures is the lipoprotein envelope, which carries external antigens - neuraminidases (N) hemagglutinin (H) - two complex proteins.

The influenza virus is divided according to its antigenic structure according to the antigenic principle. So there is influenza A and B and C.

The disease may appear to be one of its own antigenic viruses. Sometimes during the period of pandemics and epidemics, 2 types of viruses are recorded. But epidemics are promoted by influenza A and B viruses, and influenza A provokes a pandemic.

The type A virus is divided into 10 subtypes for N and 13 subspecies for H. But only the first two groups of N and three subtypes of H are dangerous for the human body.

The influenza A virus is highly variable. There are two types of variability: antigenic shift and drift. The latter are point mutations occurring in the gene that control the H antigen.

Shift is an absolute replacement of one or two surface antigens at once, that is, a whole segment of RNA, which occurs due to the exchange of genetic materials by animal and human influenza. This becomes the cause of pandemics and epidemics.

An epidemic can appear during drift, because even minimal changes in the genotype of the pathogen can disorient the cells of the immune system. Therefore, it turns out that the sick part of the population turns out to be unimmunized.

It was found that at the beginning of 2016, viruses similar to the H1 N1 swine flu circulating in 2009, influenza A (H1N1) with genetic mutations transmitted from person to person, were spreading, therefore, it is not correct to call this type “swine”.

Flu causes and symptoms

The spread of infection is a sick person. Viruses are secreted with phlegm, nasal discharge, saliva - when sneezing and coughing. In this case, the flu can be infected when the virus enters the mucous membrane of the eyes, nose or upper respiratory tract from the air, in case of close contact with the patient. Viruses often settle on different surfaces, and then get on the mucous membranes during the use of hygiene items together with the patient and through the hands.

Then the virus enters the mucous membranes of the trachea, nose, larynx and pharynx, where it multiplies rapidly. The flu virus infects the mucous membrane of the respiratory tract in just a couple of hours. But influenza A and B do not affect other organs.

Therefore, the term "intestinal flu" does not exist. Often this concept means viral gastroenteritis, manifested in the form of intoxication with diarrhea and fever.

To this day, it is not precisely determined which protective mechanisms contribute to the fact that the virus stops multiplying, due to which recovery occurs.

After 2-5 days, the virus stops infecting the environment and the patient becomes harmless.

Key features

With influenza, the incubation period is short. So, on average, after infection, the first signs appear from 2 hours to 2 days, this is the incubation period if influenza A and C and up to 4 days if influenza B.

Basically, the disease occurs in acute form - a person can even determine the time when influenza A or B appears, and feel the first signs of influenza.

The flu can be mild, moderate, or severe. In each case, there are catarrhal phenomena and manifestations of intoxication. Moreover, a hemorrhagic component appears in 5-10% of adults.

Influenza A and B begins with intoxication, which has the following symptoms:

Chills.
Elevated temperature. If the disease is mild, then the temperature is not higher than 38 degrees, for an average degree - 39-40 degrees, and if the flu is at a severe stage, then it happens that the fever reaches 40 degrees.
Malaise.
Poor appetite.
Weakness.
Nausea and vomiting.
Headache, localized in the area of \u200b\u200bthe eyes and forehead.
Painful sensations in the muscles of the legs, joints and lower back.
Severe discomfort during movement of the eyeballs.

Symptoms during the period of acute intoxication appear up to five days. If during this time the temperature has not subsided, then this may indicate the presence of complications of a bacterial nature.

Catarrhal manifestation of the disease in adults, on average, remains up to 10 days:

lacrimation;
runny nose;
pain in the eyes;
sore throat;
hoarse voice;
cough (if the course of the disease is not complicated, then it is dry).

Hemorrhagic manifestations include nosebleeds, vasodilation of the sclera, or minor hemorrhages. And on the skin, hemorrhages may appear, which are an unfavorable symptom in terms of prognosis.

The next characteristic hemorrhagic symptom in influenza is a general pallor of the skin, against which the face turns red. To there is a hemorrhage in the mucous membranes of the eyes and mouth. Moreover, H1N1 influenza A can be accompanied by diarrhea.

There are still manifestations in which it is necessary to immediately call an ambulance. They are about keeping elevated temperature for five days, shortness of breath, irregular or rapid breathing and convulsions.

More urgent medical attention and quick treatment necessary in case of impaired consciousness (forgetfulness, hallucinations or delirium) and temperatures above 40 degrees. In addition to everything, an ambulance should be called in case of a hemorrhagic skin rash and severe headache that does not subside even after taking analgesic drugs, in particular if it is localized in the back of the head.

In the presence of the above manifestations and the occurrence of other unfavorable symptoms that are not related to the picture, when influenza A is not complicated, you should immediately seek medical help and carry out the correct treatment in the future.

Who is harder to tolerate the flu virus?

This disease can be dangerous in the presence of chronic pathologies of the heart and blood vessels. In particular, for people with acquired and congenital heart defects (mitral stenosis). At the same time, it is dangerous to get the flu for people with chronic lung diseases and bronchial asthma.

Influenza A and B are difficult for patients with chronic blood and kidney pathologies, pregnant women and diabetics. This disease can harm infants and pensioners over 65 and people with immunodeficiency. All of these patient groups are prone to severe complications. Therefore, when the incubation period has passed and the first symptoms indicating influenza A and B appear, it is necessary to conduct prompt and competent treatment.

Viral and bacterial complications of influenza

One of the most severe complications of the disease is primary viral pneumonia... It occurs when a virus spreads from the upper respiratory tract through the bronchi and affected lungs. In this case, the disease is constantly progressing.

In this case, intoxication is very pronounced, shortness of breath appears, occasionally accompanied by respiratory failure. Also, if influenza A is not treated, a cough occurs with small sputum secretions, which may be mixed with blood. Often, viral pneumonia develops as a result of heart defects, namely, mitral stenosis.

The next complication that the influenza virus causes is infectious toxic shock. This phenomenon is an extreme degree of intoxication, with a violation of the kidneys, including the cardiovascular system. This is the first manifestation of toxic shock.

Pericarditis and myocarditis as complications during the period of influenza in adults appears during the Spanish flu pandemic. But today these consequences are extremely rare.

Bacterial complications of influenza that require immediate treatment include reduced resistance to infection. The fact is that the body spends all its forces on the destruction of viruses.

Consequently, bacterial infections often join the clinical picture of the disease in adults. In particular, if there are any diseases of a bacterial nature. When influenza A has been cured, they get worse, so it is better to treat them well in advance.

Bacterial complications include:

Frontitis, sinusitis, otitis media. Such complications are most common.
Glomerulonephritis is inflammatory process renal tubules, accompanied by impaired renal function.
Septic conditions that develop when bacteria enter the bloodstream and further multiply. This phenomenon is extremely serious, so it can be fatal if left untreated.
Encephalitis and meningitis are inflammation of the tissues or membranes of the brain. Often, the disease develops in patients at risk, in particular, in the presence of immunodeficiency.

In addition, pneumonia, which occurs 2 or 3 days after the acute course of the disease, is considered to be bacterial complications. Moreover, after the condition improves, the temperature rises again.

In this case, there is a cough with green or yellow sputum. It is very important not to miss the beginning of the course of this complication and to carry out timely treatment with antibiotics.

Prevention

So that the treatment of influenza in adults is not long and difficult, it is necessary to prevent viruses from getting on the mucous membranes of the mouth, eyes and nose. For this purpose, you need not to contact people with influenza A and B. Moreover, it is important to remember that viruses can remain on the personal belongings of a sick person and on surfaces in the room where he was.

For these reasons, hands should be thoroughly washed after handling objects. Do not touch your mouth, eyes and nose with unwashed hands.

It is worth noting that simple soap is not capable of killing influenza A. Since soap and water removes microorganisms mechanically, but for prevention purposes this is sufficient.

With regard to all kinds of antiseptic agents, there is no confirmed information that the components in their composition have a detrimental effect on the influenza virus. Therefore, the prevention of the disease with such formulations is impractical.

It is worth noting that the percentage of the likelihood of catching influenza A and B directly depends on the level of body resistance.

In order not to have to carry out treatment, it is necessary to maintain immunity. To this end, it is important to fully and correctly form your diet.

So, in the daily menu there should be a sufficient amount of carbohydrates, vitamins, fats, proteins. And in late autumn, early spring and winter, when there are practically no seasonal fruits, it is necessary to take vitamin complexes. In addition, prevention colds in adults includes:

Exercise regularly, including brisk walking in the fresh air.
To give up smoking. This bad habit is a significant reason for the deterioration of immunity. It has a negative effect on the body's resistance to infections and on the local protective barrier (mucous membrane of the bronchi, trachea and nose).
Avoiding stressful conditions.
Obligatory rest. Sleep should always be full, this is the only way to maintain the normal functioning of the immune system.

Every year, vaccines are developed to help fight influenza A, C and other groups of viruses. Vaccinations are carried out using vaccines designed to fight influenza A, B or C, which spread in the past winter. Consequently, its effectiveness is related to how much the previous viruses differ from the current ones.

But booster vaccinations have been found to increase the effectiveness of vaccinations. This is due to the fact that the formation of antiviral proteins, that is, antibodies in people who have been vaccinated before, is much faster.

There are currently three types of vaccines to help prevent influenza A and B infections:

Whole virion vaccines are either inactivated or live whole influenza viruses. But today such vaccines are almost never used, since they have many side effects, but most importantly, they often provoke influenza A and B.
Split vaccines are split vaccines that contain only a fraction of the virus. They have few side effects. Used to vaccinate adults to prevent influenza A and B.
Subunit vaccines are highly purified vaccines that have almost no adverse reactions. Therefore, they can be used to vaccinate children.

But when is it better to get vaccinated so as not to catch flu and other types of SARS? It is advisable to carry out this event in advance, that is, before the outbreak of the epidemic (September-December).

However, during an epidemic, it is possible to vaccinate, but you should know that immunity is formed within 1-2 weeks. Therefore, at this time, an additional one is needed, which consists in taking antiviral drugs (Remantadin).

As side effects, there may be skin redness, which disappears after a maximum of 2 days. Common reactions include chills, fever, muscle pain, and weakness. But such manifestations appear extremely rarely, and they disappear within 1-2 days.

Adults, and especially children who have been vaccinated in order not to catch influenza A and B, may be allergic to the components of the vaccine. So, it cannot be driven when a person has an intolerance to chicken protein.

If influenza A spreads quickly in a closed group or during an epidemic, then the effect of vaccination is significantly reduced, since it is necessary to wait 1-2 weeks for immunity to form.

Flu Is an acute viral infectious disease characterized by damage to the mucous membranes of the upper respiratory tract and symptoms of general intoxication of the body. The disease is prone to rapid progression, and developing complications from the lungs and other organs and systems can pose a serious danger to health and even human life.

Influenza was first described as a separate disease in 1403. Since then, about 18 pandemics have been reported ( epidemics in which the disease affects most of the country or even several countries) flu. Since the cause of the disease was unclear, and effective treatment did not exist, the majority of people with influenza died from developing complications ( the death toll was in the tens of millions). So, for example, during the Spanish flu ( 1918 - 1919) more than 500 million people were infected, of which about 100 million died.

In the middle of the 20th century was installed viral nature influenza and developed new methods of treatment, which made it possible to significantly reduce mortality ( mortality) with this pathology.

Flu virus

The causative agent of influenza is a viral microparticle containing certain genetic information encoded in RNA ( ribonucleic acid). The influenza virus belongs to the Orthomyxoviridae family and includes the genera Influenza types A, B, and C. The type A virus can infect humans and some animals ( e.g. horses, pigs), while viruses B and C are dangerous only to humans. It should be noted that the most dangerous is the type A virus, which is the cause of most influenza epidemics.

In addition to RNA, the influenza virus has a number of other components in its structure, which allows it to be divided into subspecies.

In the structure of the influenza virus, there are:

Hemagglutinin ( hemagglutinin, H) - a substance that binds erythrocytes ( red blood cells responsible for the transport of oxygen in the body).
Neuraminidase ( neuraminidase, N) - a substance responsible for damage to the mucous membrane of the upper respiratory tract.

Hemagglutinin and neuraminidase are also antigens of the influenza virus, that is, those structures that ensure the activation of the immune system and the development of immunity. Type A influenza virus antigens are prone to high variability, that is, they can easily change their external structure under the influence of various factors, while maintaining a pathological effect. This is the reason for the wide spread of the virus and the high susceptibility of the population to it. Also, due to the high variability, an outbreak of an influenza epidemic is observed every 2 to 3 years, caused by various subspecies of type A viruses, and every 10 to 30 years, a new type of this virus appears, which leads to the development of a pandemic.

Despite their danger, all influenza viruses have a rather low resistance and are quickly destroyed in the external environment.

The influenza virus dies:

As part of human secretions ( phlegm, mucus) at room temperature - in 24 hours.
At a temperature of minus 4 degrees - within a few weeks.
At a temperature of minus 20 degrees - for several months or even years.
At a temperature of plus 50 - 60 degrees - within a few minutes.
In 70% alcohol - within 5 minutes.
When exposed to ultraviolet rays ( direct sunlight) - almost instantly.

The incidence of influenza ( epidemiology)

Today, influenza and other respiratory viral infections account for more than 80% of all infectious diseases, which is due to the high susceptibility of the population to this virus. Anyone can get the flu, and the likelihood of infection does not depend on gender or age. A small percentage of the population, as well as people who have recently been ill, may be immune to the influenza virus.

The peak incidence occurs during the cold seasons ( autumn-winter and winter-spring periods). The virus spreads rapidly in collectives, often causing epidemics. From an epidemiological point of view, the most dangerous is the period of time during which the air temperature ranges from minus 5 to plus 5 degrees, and the air humidity decreases. It is in such conditions that the likelihood of contracting the flu is maximally high. On summer days, influenza is much less common without affecting large numbers of people.

How does the flu get infected?

The source of the virus is a person with the flu. People with explicit or hidden ( asymptomatic) forms of the disease. The most infectious sick person is in the first 4 - 6 days of illness, while long-term virus carrier is observed much less often ( usually in debilitated patients, as well as with the development of complications).

Influenza virus transmission occurs:

By airborne droplets. The main route of the spread of the virus that causes the development of epidemics. The virus is released into the environment from the respiratory tract of a sick person during breathing, talking, coughing or sneezing ( viral particles are found in droplets of saliva, mucus, or phlegm). In this case, all people who are in the same room with an infected patient are at risk of infection ( in the classroom, on public transport, and so on). The entrance gate ( by entering the body) in this case there may be mucous membranes of the upper respiratory tract or eyes.
Contact-household way. The possibility of transmission of the virus by contact-household means ( if virus-containing mucus or sputum gets on the surface of toothbrushes, cutlery and other items that other people later use), but the epidemiological significance of this mechanism is small.

Incubation period and pathogenesis ( development mechanism) flu

Incubation period ( the period from infection with the virus to the development of the classic manifestations of the disease) can last from 3 to 72 hours, averaging 1 to 2 days. The duration of the incubation period is determined by the strength of the virus and the initial infectious dose ( that is, the number of viral particles that entered the human body during infection), as well as the general state of the immune system.

In the development of influenza, 5 phases are conventionally distinguished, each of which is characterized by a certain stage in the development of the virus and characteristic clinical manifestations.

In the development of influenza, there are:

Reproduction phase ( breeding) virus in cells. After infection, the virus enters the epithelial cells ( upper layer of mucous membrane), starting to actively multiply inside them. As the pathological process develops, the affected cells die, and the new viral particles released during this process penetrate into neighboring cells and the process repeats. This phase lasts several days, during which the patient begins to show clinical signs of damage to the mucous membrane of the upper respiratory tract.
Phase of viremia and toxic reactions. Viremia is characterized by the entry of viral particles into the bloodstream. This phase begins in the incubation period and can last up to 2 weeks. The toxic effect in this case is due to hemagglutinin, which affects red blood cells and leads to a violation of microcirculation in many tissues. At the same time, a large amount of decay products of cells destroyed by the virus are released into the bloodstream, which also has a toxic effect on the body. This is manifested by damage to the cardiovascular, nervous and other systems.
The phase of the defeat of the respiratory tract. A few days after the onset of the disease, the pathological process in the respiratory tract is localized, that is, the symptoms of a predominant lesion of one of their departments come to the fore ( larynx, trachea, bronchi).
The phase of bacterial complications. The multiplication of the virus leads to the destruction of the cells of the respiratory epithelium, which normally perform an important protective function. As a result, the respiratory tract becomes completely defenseless in the face of many bacteria that penetrate along with the inhaled air or from oral cavity sick. Bacteria easily settle on the damaged mucous membrane and begin to develop on it, increasing inflammation and contributing to even more pronounced damage to the respiratory tract.
The phase of the reverse development of the pathological process. This phase begins after the complete removal of the virus from the body and is characterized by the restoration of the affected tissues. It is worth noting that in an adult, complete recovery of the epithelium of the mucous membrane after the flu occurs no earlier than 1 month later. In children, this process proceeds faster, which is associated with more intense cell division in the child's body.

Types and forms of influenza

As mentioned earlier, there are several types of influenza virus, and each of them is characterized by certain epidemiological and pathogenic properties.

Influenza type A

This form of the disease is caused by the influenza A virus and its variations. It occurs much more often than other forms and determines the development of most influenza epidemics on Earth.

Influenza type A includes:

Seasonal flu. The development of this form of influenza is due to various subspecies of the influenza A virus, which constantly circulate among the population and are activated in cold seasons, which causes the development of epidemics. In people who have been ill, immunity against seasonal flu persists for several years, however, due to the high variability of the antigenic structure of the virus, people can get seasonal flu every year, becoming infected with various viral strains ( subspecies).
Swine flu. Swine flu is commonly referred to as a disease that affects humans and animals and is caused by subtypes of the A virus, as well as some strains of the type C virus. The outbreak of “swine flu” registered in 2009 was caused by the A / H1N1 virus. It is assumed that the emergence of this strain occurred as a result of infection of pigs with common ( seasonal) influenza virus from humans, after which the virus mutated and led to the development of an epidemic. It should be noted that the A / H1N1 virus can be transmitted to humans not only from sick animals ( when working in close contact with them or when eating poorly processed meat), but also from sick people.
Bird flu. Avian flu is called viral disease, which primarily affects poultry and is caused by a type of influenza A virus that is similar to the human influenza virus. In birds infected with this virus, many internal organs are damaged, which leads to their death. Human infection with a virus bird flu was first registered in 1997. Since then, there have been several more outbreaks of this form of the disease, in which from 30 to 50% of infected people died. Today, human-to-human transmission of the avian influenza virus is considered impossible ( you can only get infected from sick birds). However, scientists believe that as a result of the high variability of the virus, as well as the interaction of avian and seasonal human influenza viruses, a new strain may form, which will be transmitted from person to person and may cause another pandemic.

It is worth noting that influenza A epidemics are characterized by an "explosive" character, that is, in the first 30-40 days after their onset, more than 50% of the population falls ill with influenza, and then the incidence progressively decreases. The clinical manifestations of the disease are similar and depend little on the specific subspecies of the virus.

Influenza type B and C

Influenza viruses B and C can also infect humans, but the clinical manifestations of a viral infection are mild or moderate. Mostly children, the elderly or immunocompromised patients are affected.

The type B virus is also capable of changing its antigenic composition when exposed to various environmental factors. However, it is more "stable" than the type A virus, therefore it causes epidemics extremely rarely, and no more than 25% of the country's population falls ill. The type C virus causes only sporadic ( single) cases of the disease.

Flu symptoms and signs

The clinical picture of influenza is due to the damaging effect of the virus itself, as well as the development of general intoxication of the body. Flu symptoms can vary greatly ( which is determined by the type of virus, the state of the immune system of the infected person's body and many other factors), however, in general, the clinical manifestations of the disease are similar.

Influenza can manifest itself:

general weakness;
aching muscles;
an increase in body temperature;
nasal congestion;
discharge from the nose;
bleeding from the nose;
sneezing;
cough;
eye damage.

General weakness with influenza

In classic cases, symptoms of general intoxication are the first manifestations of influenza, which appear immediately after the end of the incubation period, when the number of viral particles formed reaches a certain level. The onset of the disease is usually acute ( signs of general intoxication develop within 1 to 3 hours), and the first manifestation is a feeling of general weakness, "weakness", a decrease in endurance during physical exertion. This is due to both the penetration of a large number of viral particles into the bloodstream, and the destruction of a large number of cells and the entry of their decay products into the systemic circulation. All this leads to damage to the cardiovascular system, impaired vascular tone and blood circulation in many organs.

Flu headache and dizziness

The reason for the development of headache with influenza is the defeat of the blood vessels of the membranes of the brain, as well as the violation of microcirculation in them. All this leads to excessive dilation of blood vessels and their overfilling with blood, which, in turn, contributes to irritation of pain receptors ( with which the meninges are rich) and pain.

Headache can be localized in the frontal, temporal or occipital region, in the region of the eyebrows or eyes. As the disease progresses, its intensity gradually increases from weak or moderate to extremely pronounced ( often unbearable). Any movement or movement of the head, loud noises, or bright lights can increase the pain.

Also, from the first days of the disease, the patient may experience periodic dizziness, especially when moving from a lying position to a standing position. The mechanism for the development of this symptom is a violation of blood microcirculation at the level of the brain, as a result of which at a certain moment its nerve cells may begin to experience oxygen starvation ( due to insufficient supply of oxygen with blood). This will lead to a temporary disruption of their functions, one of the manifestations of which may be dizziness, often accompanied by darkening of the eyes or tinnitus. If this did not develop any serious complications ( for example, if dizzy, the person may fall and bump their head, resulting in a brain injury), after a few seconds, the blood supply to the brain tissues is normalized and the dizziness disappears.

Muscle aches and pains with flu

Muscle aches, stiffness and aching pains can be felt from the first hours of the disease, intensifying as it progresses. The cause of these symptoms is also a violation of microcirculation due to the action of hemagglutinin ( a viral component that "sticks together" red blood cells and thereby disrupts their circulation through the vessels).

Under normal conditions, muscles constantly need energy ( in the form of glucose, oxygen and other nutrients), which they get from blood. At the same time, by-products of their vital activity are constantly formed in muscle cells, which are normally released into the blood. When microcirculation is disturbed, both of these processes are disturbed, as a result of which the patient feels muscle weakness ( due to lack of energy), as well as a feeling of pain or aches in the muscles, which is associated with a lack of oxygen and the accumulation of metabolic by-products in the tissues.

Fever with flu

A rise in temperature is one of the earliest and most characteristic signs of influenza. The temperature rises from the first hours of the disease and can vary significantly - from subfebrile condition ( 37 - 37.5 degrees) up to 40 degrees or more. The reason for an increase in temperature with influenza is the entry into the bloodstream of a large amount of pyrogens - substances that affect the center of temperature regulation in the central nervous system. This leads to the activation of heat-generating processes in the liver and other tissues, as well as to a decrease in heat loss by the body.

Sources of pyrogens in influenza are cells of the immune system ( leukocytes). When a foreign virus enters the body, they rush to it and begin to actively fight it, while releasing many toxic substances into the surrounding tissues ( interferon, interleukins, cytokines). These substances fight a foreign agent, and also affect the thermoregulatory center, which is the direct cause of the temperature rise.

The temperature reaction in influenza develops acutely, which is due to the rapid flow of a large number of viral particles into the bloodstream and the activation of the immune system. The temperature reaches its maximum figures by the end of the first day after the onset of the disease, and starting from 2 to 3 days it can decrease, which indicates a decrease in the concentration of viral particles and other toxic substances in the blood. Quite often, a decrease in temperature can occur in waves, that is, 2 to 3 days after the onset of the disease ( usually by morning), it decreases, but in the evening rises again, normalizing after another 1 - 2 days.

A repeated increase in body temperature 6 to 7 days after the onset of the disease is an unfavorable prognostic sign, usually indicating the addition of a bacterial infection.

Chills with flu

Chills ( feeling cold) and muscle tremors are the body's natural defenses aimed at retaining heat and reducing heat loss. Normally, these reactions are activated when the ambient temperature drops, for example, during prolonged exposure to frost. In this case, temperature receptors ( special nerve endingslocated in the skin throughout the body) send signals to the thermoregulation center that it is too cold outside. As a result, a whole complex of protective reactions is triggered. First, there is a narrowing of the blood vessels of the skin. As a result, heat loss decreases, but the skin itself also becomes cold ( due to a decrease in the flow of warm blood to them). The second defense mechanism is muscle tremors, that is, frequent and rapid contractions of muscle fibers. The process of muscle contraction and relaxation is accompanied by the formation and release of heat, which contributes to an increase in body temperature.

The mechanism for the development of chills with influenza is associated with a disruption in the work of the thermoregulation center. Under the influence of pyrogens, the point of "optimal" body temperature shifts upward. As a result, the nerve cells responsible for thermoregulation "decide" that the body is too cold and trigger the mechanisms described above to increase the temperature.

Decreased appetite for flu

Decreased appetite occurs as a result of damage to the central nervous system, namely as a result of inhibition of the activity of the food center located in the brain. Under normal conditions, it is neurons ( nerve cells) of this center are responsible for the feeling of hunger, searching for and obtaining food. However, in stressful situations ( for example, when foreign viruses enter the body) all the forces of the body rush to fight the threat that has arisen, while other, less necessary functions at the moment are temporarily inhibited.

At the same time, it should be noted that a decrease in appetite does not reduce the body's needs for proteins, fats, carbohydrates, vitamins and useful microelements. In contrast, with the flu, the body needs more nutrients and energy sources to adequately fight the infection. That is why, throughout the entire period of illness and recovery, the patient should eat regularly and fully.

Flu nausea and vomiting

The appearance of nausea and vomiting is a characteristic symptom of intoxication with the flu, although the gastrointestinal tract itself is usually not affected. The mechanism of occurrence of these symptoms is due to the entry into the bloodstream of a large amount of toxic substances and decay products formed as a result of cell destruction. These substances with the blood flow reach the brain, where the trigger ( launcher) zone of the vomiting center. When the neurons of this zone are irritated, a feeling of nausea appears, accompanied by certain manifestations ( increased salivation and sweating, pallor of the skin).

Nausea may persist for some time ( minutes or hours), however, with a further increase in the concentration of toxins in the blood, vomiting occurs. During the gag reflex, the muscles of the stomach, the anterior abdominal wall and the diaphragm contract ( respiratory muscle located on the border between the chest and abdominal cavity), as a result of which the contents of the stomach are pushed into the esophagus, and then into the oral cavity.

Vomiting with influenza can be observed 1 - 2 times during the entire acute period of the disease. It should be noted that due to a decrease in appetite, the patient's stomach often turns out to be empty during the onset of vomiting ( it may contain only a few milliliters of gastric juice). With an empty stomach, vomiting is more difficult to tolerate, since muscle contractions during the gag reflex are longer and more painful for the patient. That is why, with a premonition of vomiting ( that is, when severe nausea appears), and also after it it is recommended to drink 1 - 2 glasses of warm boiled water.

It is also important to note that vomiting with influenza can appear without prior nausea, against the background of severe cough. The mechanism of development of the gag reflex in this case is that during an intense cough, there is a pronounced contraction of the muscles of the abdominal wall and an increase in pressure in the abdominal cavity and in the stomach itself, as a result of which food "pushing" into the esophagus and the development of vomiting can occur. Also, vomiting can be provoked by clots of mucus or sputum that gets on the mucous membrane of the pharynx during coughing, which also leads to the activation of the vomiting center.

Flu nasal congestion

Signs of damage to the upper respiratory tract can occur simultaneously with symptoms of intoxication or several hours after them. The development of these signs is associated with the multiplication of the virus in the epithelial cells of the respiratory tract and with the destruction of these cells, which leads to dysfunction of the mucous membrane.

Nasal congestion can occur if the virus enters the human body through the nasal passages along with the inhaled air. In this case, the virus invades the epithelial cells of the nasal mucosa and actively multiplies in them, causing their death. The activation of local and systemic immune responses is manifested by the migration of cells of the immune system to the site of introduction of the virus ( leukocytes), which, in the process of fighting the virus, release many biologically active substances into the surrounding tissues. This, in turn, leads to the expansion of the blood vessels of the nasal mucosa and their overflow with blood, as well as to an increase in the permeability of the vascular wall and the release of the liquid part of the blood into the surrounding tissues. As a result of the described phenomena, swelling and edema of the nasal mucosa occurs, which blocks most of the nasal passages, making it difficult for air to move through them during inhalation and exhalation.

Flu nasal discharge

The nasal mucosa contains special cells that produce mucus. Under normal conditions, this mucus is produced in a small amount necessary to moisturize the mucous membrane and purify the inhaled air ( dust microparticles are retained in the nose and settle on the mucous membrane). When the nasal mucosa is affected by the influenza virus, the activity of mucus-producing cells increases significantly, as a result of which patients may complain of profuse nasal discharge of a mucous nature ( transparent, colorless, odorless). As the disease progresses, the protective function of the nasal mucosa is impaired, which contributes to the addition of a bacterial infection. As a result, pus begins to appear in the nasal passages, and the discharge becomes purulent ( yellow or greenish in color, sometimes with an unpleasant odor).

Flu nosebleeds

Bleeding from the nose is not a flu-specific symptom. Nevertheless, this phenomenon can be observed with pronounced destruction of the epithelium of the mucous membrane and damage to its blood vessels, which can be facilitated by mechanical trauma ( for example, when picking your nose). The amount of blood released during this can vary within significant limits ( from subtle streaks to profuse bleeding that lasts for several minutes), however, usually this phenomenon does not pose a threat to the patient's health and disappears a few days after the acute period of the disease subsides.

Sneezing with flu

Sneezing is a protective reflex designed to remove various "extra" substances from the nasal passages. With influenza, a large amount of mucus accumulates in the nasal passages, as well as many fragments of dead and rejected epithelial cells of the mucous membrane. These substances irritate certain receptors in the nose or nasopharynx, which triggers the sneezing reflex. A person has a characteristic tickling sensation in the nose, after which he draws in full lungs of air and exhales it sharply through the nose, closing his eyes ( sneezing with open eyes is impossible).

The air stream generated during sneezing moves at a speed of several tens of meters per second, capturing dust microparticles, rejected cells and virus particles on the surface of the mucous membrane on its way, and removing them from the nose. The negative point in this case is the fact that the air exhaled during sneezing contributes to the spread of microparticles containing the influenza virus to a distance of 2 - 5 meters from the sneezer, as a result of which all people in the affected area can become infected with the virus.

Sore throat with flu

The occurrence of a sore throat or sore throat is also associated with the damaging effect of the influenza virus. When it enters the upper respiratory tract, it destroys the upper mucous membranes of the pharynx, larynx and / or trachea. As a result, a thin layer of mucus is removed from the surface of the mucous membrane, which normally protected tissues from damage ( including inhaled air). Also, with the development of the virus, there is a violation of microcirculation, expansion of blood vessels and edema of the mucous membrane. All this leads to the fact that she becomes extremely sensitive to various stimuli.

In the first days of the disease, patients may complain of a sore or sore throat. This is due to the death of epithelial cells, which are rejected and irritate the sensitive nerve endings. In the future, the protective properties of the mucous membrane are reduced, as a result of which patients begin to experience pain during a conversation, when swallowing solid, cold or hot food, with a sharp and deep breath or exhale.

Flu cough

Cough is also a protective reflex aimed at clearing the upper respiratory tract from various foreign objects ( mucus, dust, foreign bodies etc). The nature of the flu cough depends on the period of the illness, as well as on the developing complications.

In the first days after the onset of flu symptoms, the cough is dry ( without sputum production) and painful, accompanied by severe stabbing or burning pain in the chest and throat. The mechanism of development of cough in this case is due to the destruction of the mucous membrane of the upper respiratory tract. Desquamated epithelial cells irritate specific cough receptors, which triggers the cough reflex. After 3 to 4 days, the cough becomes moist, that is, it is accompanied by the release of mucous sputum ( colorless, odorless). Purulent sputum that appears 5 to 7 days after the onset of the disease ( greenish with an unpleasant odor) indicates the development of bacterial complications.

It is worth noting that when coughing, as when sneezing, a large number of viral particles are released into the environment, which can cause infection of the people around the patient.

Influenza Eye Damage

The development of this symptom is due to the ingress of viral particles on the mucous membrane of the eyes. This leads to damage to the blood vessels of the conjunctiva of the eye, which is manifested by their pronounced expansion and increased permeability of the vascular wall. The eyes of such patients are red ( due to the pronounced vascular network), the eyelids are swollen, lacrimation and photophobia are often noted ( pain and burning sensation in the eyes, arising in normal daylight).

Conjunctivitis phenomena ( inflammation of the conjunctiva) are usually short-lived and subside along with the removal of the virus from the body, however, with the addition of a bacterial infection, purulent complications may develop.

Flu symptoms in newborns and children

Children get the flu virus as often as adults. At the same time, the clinical manifestations of this pathology in children have a number of features.

The flu course in children is characterized by:

The tendency to damage the lungs. Influenza virus infection in adults is extremely rare. At the same time, in children, due to certain anatomical features ( short trachea, short bronchi) the virus spreads rather quickly through the respiratory tract and infects the pulmonary alveoli, through which oxygen is normally transported into the blood and the removal of carbon dioxide from the blood. The destruction of the alveoli can lead to the development of respiratory failure and pulmonary edema, which, without urgent medical attention, can lead to the death of the baby.
A tendency to nausea and vomiting. In children and adolescents ( between the ages of 10 and 16) nausea and vomiting with influenza are most common. It is assumed that this is due to the imperfection of the regulatory mechanisms of the central nervous system, in particular, the increased sensitivity of the vomiting center to various stimuli ( to intoxication, to pain syndrome, to irritation of the pharyngeal mucosa).
A tendency to develop seizures. Newborns and infants are most at risk of developing seizures ( involuntary, pronounced and extremely painful muscle contractions) with flu. The mechanism of their development is associated with an increase in body temperature, as well as with impaired microcirculation and delivery of oxygen and energy to the brain, which ultimately leads to impaired function of nerve cells. Due to certain physiological characteristics in children, these phenomena develop much faster and are more severe than in adults.
Weakly expressed local manifestations. The child's immune system has not yet been formed, which is why it is not able to adequately respond to the introduction of foreign agents. As a result, among the symptoms of influenza, pronounced manifestations of intoxication of the body come to the fore, while local symptoms can be erased and mild ( there may be a slight cough, nasal congestion, periodic appearance of mucous discharge from the nasal passages).

The severity of the flu

The severity of the disease is determined depending on the nature and duration of its clinical manifestations... The more pronounced the intoxication syndrome, the harder the flu is tolerated.

Depending on the severity, there are:

A mild form of flu. With this form of the disease, the symptoms of general intoxication are insignificant. Body temperature rarely reaches 38 degrees and usually returns to normal after 2 to 3 days. There is no threat to the patient's life.
Flu of moderate severity. The most common variant of the disease, in which there are severe symptoms of general intoxication, as well as signs of damage to the upper respiratory tract. Body temperature can rise to 38 - 40 degrees and remain at this level for 2 - 4 days. With the timely start of treatment and the absence of complications, there is no threat to the patient's life.
Severe flu. It is characterized by fast ( during few hours) the development of intoxication syndrome, accompanied by an increase in body temperature up to 39 - 40 degrees or more. Patients are lethargic, drowsy, often complain of severe headaches and dizziness, and may faint. Fever can persist for a week, and developing complications from the lungs, heart and other organs can pose a threat to the patient's life.
Hypertoxic ( lightning fast) form. It is characterized by an acute onset of the disease and rapid damage to the central nervous system, heart and lungs, which in most cases leads to the death of the patient within 24 to 48 hours.

Gastric ( intestinal) flu

This pathology is not influenza and has nothing to do with influenza viruses. The very name "stomach flu" is not a medical diagnosis, but the popular "nickname" of rotavirus infection ( gastroenteritis) - a viral disease that is provoked by rotaviruses ( rotavirus from the family reoviridae). These viruses penetrate into the human digestive system along with ingested contaminated food and infect the cells of the mucous membrane of the stomach and intestines, causing their destruction and the development of the inflammatory process.

The source of infection can be a sick person or a hidden carrier ( a person in whose body there is a pathogenic virus, but there are no clinical manifestations of infection). The main mechanism for the spread of infection is fecal-oral, that is, the virus is excreted from the patient's body along with the feces, and if the rules of personal hygiene are not followed, it can get into various food products. If a healthy person eats these foods without special heat treatment, he runs the risk of contracting the virus. Less common is the airborne path of spread, in which a sick person releases microparticles of the virus along with the exhaled air.

All people are susceptible to rotavirus infection, but children and the elderly, as well as patients with immunodeficiency states ( e.g. patients with acquired immunodeficiency syndrome (AIDS)). The peak of the incidence occurs in the autumn-winter period, that is, at the same time when influenza epidemics are observed. Perhaps this was the reason for the people to call this pathology stomach flu.

The mechanism of development of intestinal flu is as follows. Rotavirus enters the human digestive system and infects the cells of the intestinal mucosa, which normally ensure the absorption of food from the intestinal cavity into the blood.

Intestinal flu symptoms

Symptoms of rotavirus infection are caused by damage to the intestinal mucosa, as well as the penetration of viral particles and other toxic substances into the systemic circulation.

Rotavirus infection manifests itself:

Vomiting. This is the first symptom of the disease, which is observed in almost all patients. The occurrence of vomiting is caused by a violation of the absorption of food and the accumulation of large volumes of food in the stomach or intestines. Vomiting with intestinal flu is usually single, but it can be repeated 1 - 2 more times during the first day of the disease, and then stops.
Diarrhea ( diarrhea). The onset of diarrhea is also associated with impaired absorption of food and migration of large amounts of water into the intestinal lumen. The feces that stand out at the same time are usually liquid, frothy, they have a characteristic fetid odor.
Abdominal pain. The occurrence of pain is associated with damage to the intestinal mucosa. The pains are localized in the upper abdomen or in the navel, are aching or pulling in nature.
Rumbling in the stomach. It is one of the characteristic signs of intestinal inflammation. The onset of this symptom is due to increased peristalsis ( motor skills) of the intestine, which is stimulated by large amounts of unprocessed food.
Symptoms of general intoxication. Patients usually complain of general weakness and increased fatigue, which is associated with impaired intake of nutrients into the body, as well as with the development of an acute infectious and inflammatory process. Body temperature rarely exceeds 37.5 - 38 degrees.
The defeat of the upper respiratory tract. May manifest as rhinitis ( inflammation of the nasal mucosa) or ( inflammation of the pharynx).

Intestinal flu treatment

This disease is fairly easy, and treatment is usually aimed at eliminating the symptoms of infection and preventing the development of complications.

Treatment for intestinal flu includes:

Restoration of water and electrolyte losses ( which are lost along with vomit and with diarrhea). Patients are prescribed a plentiful drink, as well as special preparations containing the necessary electrolytes ( e.g. rehydron).
A gentle diet that avoids fatty, spicy, or poorly processed foods.
Sorbents ( activated carbon, polysorb, filterum) - drugs that bind various toxic substances in the intestinal lumen and promote their removal from the body.
Preparations that restore intestinal microflora ( linex, bifidumbacterin, hilak forte and others).
Anti-inflammatory drugs ( indomethacin, ibufen) are prescribed only with a pronounced intoxication syndrome and an increase in body temperature of more than 38 degrees.

Influenza diagnosis

In most cases, the diagnosis of influenza is based on the symptoms of the disease. It is worth noting that to distinguish influenza from other acute respiratory viral infections ( ) is extremely difficult, therefore, when making a diagnosis, the doctor is also guided by data on the epidemiological situation in the world, country or region. An outbreak of an influenza epidemic in the country creates a high probability that every patient with characteristic clinical manifestations may have this particular infection.

Additional studies are prescribed only in severe cases, as well as to identify possible complications from various organs and systems.

Which doctor should I go to for the flu?

At the first sign of the flu, you should consult your family doctor as soon as possible. A visit to the doctor is not recommended to be postponed indefinitely, since the flu progresses quite quickly, and with the development of serious complications from the vital organs, it is not always possible to save the patient.

If the patient's condition is very serious ( that is, if symptoms of general intoxication do not allow him to get out of bed), you can call a doctor at home. If the general condition allows you to visit the clinic yourself, you should not forget that the influenza virus is extremely contagious and can easily be transmitted to other people when traveling in public transport, while waiting for their turn in front of the doctor's office and under other circumstances. To prevent this, it is imperative for a person with flu symptoms to wear a medical mask before leaving the house and not remove it until they return home. This preventive measure does not guarantee one hundred percent safety for others, however, it significantly reduces the risk of their infection, since the viral particles exhaled by a sick person are retained on the mask and do not enter the environment.

It is worth noting that one mask can be used continuously for a maximum of 2 hours, after which it must be replaced with a new one. It is strictly forbidden to reuse the mask or take an already used mask from other people ( including from children, parents, spouses).

Do I need hospitalization for the flu?

In classic and uncomplicated cases, influenza treatment is carried out on an outpatient basis ( at home). At the same time, the family doctor must explain to the patient in detail and understand the essence of the disease and give detailed instructions on the treatment, as well as warn about the risks of infection of the surrounding people and about possible complications that may develop in case of violation of the treatment regimen.

Hospitalization of patients with influenza may be required only if the patient is in extremely serious condition ( for example, with an extremely pronounced intoxication syndrome), as well as with the development of serious complications from various organs and systems. Also, children who have developed convulsions against the background of an elevated temperature are subject to compulsory hospitalization. In this case, the probability of recurrence ( re-emergence) convulsive syndrome is extremely high, therefore, the child should be under the supervision of doctors for at least several days.

If the patient is hospitalized during the acute period of the disease, he is sent to the infectious diseases department, where he is placed in a specially equipped ward or box ( insulator). A visit to such a patient is prohibited throughout the acute period of the disease, that is, until the release of viral particles from his respiratory tract stops. If the acute period of the disease has passed, and the patient is hospitalized due to developing complications from various organs, he can be sent to other departments - to the cardiology department with heart damage, to the pulmonology department with lung damage, to the intensive care unit with severe disruption of vital functions. important organs and systems and so on.

In diagnosing influenza, a doctor may use:

clinical examination;
general blood analysis ;
general urine analysis ;
nasal swab analysis;
sputum analysis;
analysis for the detection of antibodies to the influenza virus.

Clinical examination for influenza

The clinical examination is carried out by the family doctor at the first visit of the patient. It allows you to assess the general condition of the patient and the degree of damage to the pharyngeal mucosa, as well as to identify some possible complications.

The clinical examination includes:

Inspection. During the examination, the doctor visually assesses the patient's condition. In the first days of the development of influenza, severe hyperemia is noted ( redness) of the mucous membranes of the pharynx, which is due to the expansion of the blood vessels in it. After a few days, small punctate hemorrhages may appear on the mucous membrane. Eye redness and watery eyes may also occur. In a severe course of the disease, pallor and cyanosis of the skin may be observed, which is associated with damage to microcirculation and impaired transport of respiratory gases.
Palpation ( probing). By palpation, the doctor can assess the condition of the lymph nodes in the neck and other areas. With the flu, swollen lymph nodes usually do not occur. In the same time, this symptom is characteristic of an adenoviral infection that causes ARVI and proceeds with a generalized enlargement of the submandibular, cervical, axillary and other groups of lymph nodes.
Percussion ( tapping). With the help of percussion, the doctor can examine the patient's lungs and identify various complications of the flu ( e.g. pneumonia). During percussion, the doctor presses the finger of one hand to the surface chest, and with the finger of his other hand taps on it. By the nature of the sound generated, the doctor draws conclusions about the condition of the lungs. So, for example, healthy lung tissue is filled with air, as a result of which the resulting percussion sound will have a characteristic sound. With the development of pneumonia, the pulmonary alveoli are filled with leukocytes, bacteria and inflammatory fluid ( exudate), as a result of which the amount of air in the affected area of \u200b\u200bthe lung tissue decreases, and the resulting percussion sound will have a dull, muffled character.
Auscultation ( listening). During auscultation, the doctor applies a membrane of a special device ( phonendoscope) to the surface of the patient's chest and asks him to take several deep breaths and exhalations. By the nature of the noise generated during breathing, the doctor draws conclusions about the condition of the pulmonary tree. So, for example, with inflammation of the bronchi ( bronchitis) their lumen narrows, as a result of which the air passing through them moves at a high speed, creating a characteristic noise, which is assessed by the doctor as hard breathing. At the same time, with some other complications, breathing over certain parts of the lung may be weakened or completely absent.

Complete blood count for influenza

A complete blood count does not directly detect the influenza virus or confirm the diagnosis. At the same time, with the development of a symptom of general intoxication of the body, certain changes are observed in the blood, the study of which makes it possible to assess the severity of the patient's condition, identify possible developing complications and plan treatment tactics.

A general analysis for influenza allows you to identify:

Change in the total number of leukocytes ( norm - 4.0 - 9.0 x 10 9 / l). Leukocytes are cells of the immune system that provide the body's defense against foreign viruses, bacteria and other substances. When infected with the influenza virus, the immune system is activated, which is manifested by increased division ( reproduction) leukocytes and the entry of a large number of them into the systemic circulation. However, a few days after the onset of clinical manifestations of the disease, most of the leukocytes migrate to the inflammatory focus to fight the virus, as a result of which their total number in the blood may decrease somewhat.
An increase in the number of monocytes. Under normal conditions, monocytes account for 3 to 9% of all leukocytes. When the influenza virus enters the body, these cells migrate to the site of infection, penetrate the infected tissues and turn into macrophages, which directly fight the virus. That's why with the flu ( and other viral infection) the rate of formation of monocytes and their concentration in the blood increases.
An increase in the number of lymphocytes. Lymphocytes are leukocytes that regulate the activity of all other cells of the immune system, and also take part in the fight against foreign viruses. Under normal conditions, lymphocytes account for 20 to 40% of all leukocytes, but with the development of a viral infection, their number may increase.
Decrease in the number of neutrophils ( norm - 47 - 72%). Neutrophils are cells of the immune system that provide the fight against foreign bacteria. When the influenza virus enters the body, the absolute number of neutrophils does not change, however, due to an increase in the proportion of lymphocytes and monocytes, their relative number may decrease. It should be noted that with the addition of bacterial complications in the blood, pronounced neutrophilic leukocytosis will be noted ( an increase in the number of leukocytes mainly due to neutrophils).
An increase in the erythrocyte sedimentation rate ( ESR). Under normal conditions, all blood cells carry a negative charge on their surface, as a result of which they are slightly repelled from each other. When blood is placed in a test tube, it is the severity of this negative charge that determines the rate at which the red blood cells will settle to the bottom of the test tube. With the development of an infectious-inflammatory process, a large amount of the so-called proteins of the acute phase of inflammation ( C-reactive protein, fibrinogen and others). These substances contribute to the adhesion of erythrocytes to each other, as a result of which the ESR increases ( more than 10 mm per hour for men and more than 15 mm per hour for women). It is also worth noting that ESR can increase as a result of a decrease in the total number of red blood cells in the blood, which can be observed with the development of anemia.

Urinalysis for influenza

For uncomplicated flu, data general analysis urine does not change, since renal function is not impaired. At the peak of the temperature rise, slight oliguria ( decrease in the amount of urine excreted), which is more due to increased fluid loss through sweating than damage to the kidney tissue. Also in this period, the appearance of protein in the urine may be noted ( normally it is practically absent) and an increase in the number of erythrocytes ( red blood cells) more than 3 - 5 in the field of view. These phenomena are temporary and disappear after the normalization of body temperature and the abatement of acute inflammatory processes.

Flu nasal swab

One of the reliable diagnostic methods is the detection of viral particles in various secretions. For this purpose, material is taken, which is then sent for research. In the classic form of influenza, the virus is found in large quantities in the nasal mucus, making a nasal swab one of the most effective ways to obtain a viral culture. The sampling procedure itself is safe and painless - the doctor takes a sterile cotton swab and runs it several times over the surface of the nasal mucosa, then packs it into an airtight container and sends it to the laboratory.

With a conventional microscopic examination, the virus cannot be detected, since its size is extremely small. Also, viruses do not grow on conventional culture media, which are intended only for the detection of bacterial infectious agents. For the purpose of growing viruses, the method of their cultivation on chicken embryos is used. The technique of this method is as follows. First, the fertilized chicken egg is placed in an incubator for 8 to 14 days. Then it is removed and the test material, which may contain viral particles, is injected into it. After that, the egg is again placed in the incubator for 9 to 10 days. If there is an influenza virus in the test material, it invades the cells of the embryo and destroys them, as a result of which the embryo itself dies.

Sputum analysis for influenza

Excretion of sputum in patients with influenza is noted 2 to 4 days after the onset of the disease. Sputum, like nasal mucus, can contain a large amount of viral particles, which makes it possible to use it for cultivation ( cultivation) virus in a chicken embryo. Also, sputum may contain impurities of other cells or substances, which will make it possible to identify developing complications in time. So, for example, the appearance of pus impurities in the sputum may indicate the development of bacterial pneumonia ( pneumonia). Also, bacteria can be isolated from sputum, which are the direct causative agents of infection, which will allow to prescribe in a timely manner correct treatment and prevent the progression of pathology.

Influenza virus antibody test

When a foreign virus enters the body, the immune system begins to fight it, as a result of which specific antiviral antibodies are formed, which circulate in the patient's blood for a certain time. It is on the detection of these antibodies that the serological diagnosis of influenza is based.

There are many methods for detecting antiviral antibodies, but the most widespread reaction is the inhibition of hemagglutination ( RTGA). Its essence is as follows. Plasma is placed in a test tube ( liquid part of blood) of a patient to which a mixture containing active influenza viruses is added. After 30 - 40 minutes, chicken erythrocytes are added to the same test tube and further reactions are observed.

Under normal conditions, the influenza virus contains a substance called hemagglutinin, which binds red blood cells. If chicken erythrocytes are added to the mixture containing the virus, hemagglutinin will cause them to stick together, which will be visible to the naked eye. If plasma containing antiviral antibodies is first added to the mixture containing the virus, they ( these antibodies) will block hemagglutinin, as a result of which agglutination will not occur with the subsequent addition of chicken erythrocytes.

Differential diagnosis of influenza

Differential diagnostics must be carried out in order to distinguish several diseases from each other with similar clinical manifestations.

With the flu differential diagnosis held:

With adenovirus infection. Adenoviruses also infect the mucous membranes of the respiratory tract, causing the development of ARVI ( acute respiratory viral infections). The intoxication syndrome that develops in this case is usually moderately expressed, but the body temperature can rise to 39 degrees. Also an important distinguishing feature is an increase in the submandibular, cervical and other groups of lymph nodes, which occurs in all forms of ARVI and is absent in influenza.
With parainfluenza. Parainfluenza is caused by the parainfluenza virus and also occurs with symptoms of damage to the mucous membrane of the upper respiratory tract and signs of intoxication. At the same time, the onset of the disease is less acute than with influenza ( symptoms may appear and progress over several days). Intoxication syndrome is also less pronounced, and body temperature rarely exceeds 38 - 39 degrees. With parainfluenza, there may also be an increase in the cervical lymph nodes, while eye damage ( conjunctivitis) does not occur.
With respiratory syncytial infection. It is a viral disease characterized by damage to the lower respiratory tract ( bronchi) and moderate symptoms of intoxication. Mostly children of primary school age get sick, while in adults the disease is extremely rare. The disease proceeds with a moderate increase in body temperature ( up to 37 - 38 degrees). Headaches and muscle pains are rare, and eye damage is not observed at all.
With a rhinovirus infection. This is a viral disease characterized by damage to the nasal mucosa. Manifested by nasal congestion, which is accompanied by profuse mucous secretions. Sneezing and dry cough are common. Signs of general intoxication are very weak and can manifest themselves as a slight increase in body temperature ( up to 37 - 37.5 degrees), mild headaches, poor exercise tolerance.

Capable of infecting humans, animals and birds. It represents the greatest danger in epidemiological terms, since it is capable of rapid genetic change. Various combinations of gemaglutinin and neuraminidase on the surface make it possible to divide the type A virus into subtypes H1N1, H3N2, etc. In recent years, the A virus subtype H3N2 dominates. Such variability of surface antigens leads to the formation of new types of viruses, followed by their selection under the influence of immunological factors of the population. In this regard, influenza "A" viruses have the greatest variety of types, virulence and contagiousness and can cause epidemics on the scale of individual countries and pandemics.

Influenza viruses "A" with surface antigens A (H1N1), A (H2N2), A (H3N2) have been epidemiologically significant for humans in the last 10 years. In recent years, influenza "A" viruses with surface antigens H5N1, H7N7 and H9N7 have also appeared.

Typical of influenza A epidemics is their rapid development. In a short period of time, almost all cities in the country are involved in the epidemic. There is a high incidence of the population (up to 40%) with almost the same damage to all age groups. For many years it was believed that influenza "A" epidemics occur at intervals of 2-3 years, but since 1977, influenza "A" epidemics began to occur almost every year.

Avian influenza A / H5N1

Avian influenza is an infectious disease of birds caused by viruses. The disease was identified in Italy over 100 years ago. Natural reservoir is waterfowl. Can also affect pigs, horses, foxes.

The H5N1 influenza virus has acquired the ability to infect humans and cause serious human illness. A person can become infected through close contact with infected and dead poultry and wild birds. Sometimes this can happen when eating meat and eggs of sick birds, if they have not been subjected to sufficient heat treatment, through plants infected with the secretions of birds, water and air when bathing. Human infection occurs by airborne droplets, and.

The first case of direct bird-to-human transmission and disease was reported in Hong Kong in 1997. To date, since 2003, WHO has registered 218 cases of human disease caused by the H5N1 avian influenza virus, of which 124 people have died (56.9%). Cases of diseases have been registered among people in 10 countries (Vietnam, Thailand, Indonesia, Cambodia, China, Turkey, Iraq, Azerbaijan, Egypt, Djibouti).

Swine flu A / H1N1

A / H1N1 (known as<свиной грипп>) is a new influenza virus that causes illness in humans. This new virus was first detected in humans in the United States in April 2009. Other countries, including Mexico and Canada, are also reporting human cases of the new virus. This virus spreads from one person to another in much the same way as a normal seasonal one.

What are the main signs and symptoms of this virus in humans? The symptoms of the new H1N1 flu virus are similar to those of the seasonal flu. Among them heat, cough, sore throat, runny or stuffy nose, body aches, headachechills and feeling tired. Many of the infected patients also complained of diarrhea and vomiting. In addition, as with seasonal flu, serious and even fatal cases have been reported as a result of the disease caused by this virus. Therefore, in case of illness, it is imperative to consult a doctor for a qualified diagnosis.

Take the following measures to protect your health:

Cover your nose and mouth with a paper towel when you cough or sneeze. Dispose of the used tissue in the trash.
Wash your hands thoroughly and often with soap and water, especially after a cough or sneeze. Alcohol-based hand cleaners are also effective.
Do not touch your eyes, nose, or mouth. The infection is transmitted in this way.
Try to avoid close contact with sick people.
If you get sick, stay at home for 7 days after showing symptoms or until symptoms appear within 24 hours, whichever lasts longer. This is to prevent infection of others and the further spread of the virus.

The flu is acute infectious disease respiratory tract, which is caused by a virus. The influenza virus is widespread in nature. Animals and people are susceptible to the disease. Flu symptoms are similar to those of a cold. Complications of influenza are serious and in some cases fatal. The disease is especially dangerous for young children with severe chronic diseases and the elderly.

The virus multiplies rapidly and evolves easily. The incubation period for influenza is short, often several hours. Among all respiratory diseases only with the flu are the symptoms of intoxication pronounced, which begins to develop from the first hours of the disease. Redness of the soft palate and pharynx, high body temperature are the main symptoms of the flu.

Figure: 1. The photo shows a schematic structure of the influenza virus.

The flu has claimed many lives on the planet. Its epidemics are reported annually. In the 19th century alone, 45 epidemics were recorded.

The infamous Spanish flu epidemic in 1918 killed 20 million people. She went around the entire planet in a year and a half. In 1957, the "Asian flu" bypassed the entire planet in 7 months. The pandemic has claimed the lives of over 1 million people. In 1968, the "Hong Kong flu" raged on the planet. He claimed the lives of 2.5 million people. In 1931, "swine flu" was discovered, the last epidemic of which was registered in Russia in 2016.

Every year in the world 300 - 500 thousand people die from complications of influenza.

The causative agent of influenza is evolving at an astonishing rate. Scientists don't have time to create new vaccines. Epidemics with a high number of deaths occur every 12 years. Epidemics with fewer casualties are reported annually.

In Russia, more than 30 million people are sick with the flu every year.

Among all respiratory infections influenza accounts for up to 12%. The remaining 88% account for:

parainfluenza viruses - up to 50%,
adenovirus infections - up to 5%,
respiratory syncytial virus - up to 4%,
mycoplasma - up to 2.7%,
enteroviruses - up to 1.2%.

Mixed infections account for up to 23% of cases. Of all the above infections, only the influenza virus is the cause of devastating pandemics with high morbidity and mortality.

In autumn, parainfluenza viruses are more likely to infect humans, in winter - respiratory syncytial and influenza viruses, in late summer and early autumn - enteroviruses, adenoviruses infect humans throughout the year.

Flu virus

The flu virus was first discovered in 1933. This is an RNA-containing virus of the orthomyxovirus family, which has three antigen of independent serotypes - A, B, C.

Figure: 2. The photo shows the structure of the influenza virus (3D model on the left and diagram on the right). The virus has an elongated shape. Its oblong shape is due to the matrix - the structural protein M2, which contains 8 RNA molecules twisted into a spiral. They make up the genome of the virus. Viral particles are thousands of times thinner than a human hair.

Figure: 3. The photo shows influenza viruses in the light of an electron microscope.

Figure: 4. The photo shows the flu virus (3D model). Its outer side is represented by a membrane, in the structure of which surface proteins (hemagglutinin and neuraminidase) are located. The membrane is riddled with ion channels.

Hemagglutinin allows the virus to bind to the host's cells and penetrate deep into it. Neuramidase promotes the separation of newly formed viral particles from the cell for subsequent penetration into new host cells.

Hemagglutinin and neuraminidase determine the narrow specificity of viruses - toxigenicity, variability and immunogenicity.

Figure: 5. The photo shows the influenza virus (3D model). The M2 protein of the virus contributes to the formation of channels through which hydrogen ions penetrate into it, triggering the mechanisms for the correct unpacking of the genome and the production of RNA copies.

Figure: 6. The photo shows the flu virus (3D model). The polymerase complex is involved in the creation of copies of the RNA of the virus and the synthesis of structural proteins for new viruses.

The nuclear export protein delivers copies of RNA to the site where new viral particles are collected and packs them into a matrix. Further, the membrane of the virus is formed from the elements of the membrane of the affected cell.

Influenza virus strains

The flu virus was first discovered in 1933. It is an RNA-containing virus of the orthomyxovirus family. They have three antigenically independent serotypes - A, B, C.

Hemagglutinin contributes to the formation of antibodies neutralizing the virus by the human body. This protein consists of hundreds of amino acids and is highly variable. It is because of this that new strains of the influenza virus appear every year, and scientists have to constantly change strains for the vaccine.

Neuraminidase, which promotes the penetration of the virion into the host cells, also has antigenic properties.

Every 20 to 30 years, a new influenza virus serotype is formed. The change in serotype is responsible for a pandemic of the disease.

Influenza A virus is the culprit in the most severe forms of the disease. It is isolated from pigs, horses and birds. Serotypes B and C viruses are dangerous only for humans.

Influenza B viruses less volatile. The disease is local in nature and is more common in large groups.

Influenza C viruses cause only sudden (sporadic) cases of disease, often in children of the first year of life. Its antigenic structure is constant and, as a rule, all children from the age of 10 have antibodies to this virus.

Swine flu was discovered in the United States in 1931 by the scientist Richard Shoup. Strains associated with outbreaks of “swine flu” have been found among influenza viruses of serotype C and serotype A subtypes (influenza H1N1, H1N2, H3N1, H3N2 and H2N3). The causative agent of bird flu is the RNA virus Influenza virus A. It belongs to the Orthomyxoviridae family. The complement-binding antigen (RNP) is related to influenza A virus.

Epidemiology and pathogenesis of the disease

The source of the influenza virus is a sick person. It remains highly contagious from the first hours of the disease to 3 - 5 days. Patients with erased forms of the disease contribute to the massive spread of the disease. When you cough and sneeze, viruses spread into the environment with the slightest droplets of moisture. With particles of moisture from the patient, with dust from the floor and household items of the patient, they enter the body of a healthy person.

Warming up to 50 ° C and the effect of disinfectants on viruses manifests itself instantly.

Reproduction of viruses occurs in the cytoplasm of the epithelial cells of the respiratory tract. Particularly sensitive is the columnar epithelium of the inferior turbinates and trachea, which is damaged, necrotic and slough off. Then the viruses penetrate into the blood and affect the vascular endothelium, increasing their permeability. The blood vessels dilate and overflow with blood. Hemorrhages occur, blood clots form, and DIC syndrome develops.

With influenza, the blood vessels and the nervous system (central and autonomic) are primarily affected.

Resists viruses:

Protect the body from ds-RNA-dependent viruses protein kinase and induction of type 1 interferon, the activation of which is associated with the multiplication of viruses. As a result of their influence, viruses begin to die in 20 - 40 hours from the moment of division (replication).
Special subpopulations of blood cells protect the body from viruses lymphocytes.

Suppression of immunity leads to the development of secondary flora, which contributes to the development of bacterial complications.

Flu signs and symptoms

The incubation period for influenza lasts from several hours to 3 - 5 days. Further, the period of development of the disease begins. The severity of the course of the disease is influenced by the age of the patient and the type of virus.

Intoxication syndrome

Among all respiratory diseases of the upper respiratory tract, only with the flu are the intoxication syndrome pronounced, which begins to develop already from the first hours of the disease:

Body temperature in a short time, it rises to the maximum indicators and lasts for a short time (up to 3 - 5 days with influenza A and up to 7 days with influenza B). Another character of the temperature indicates bacterial complication... Fever is accompanied by chills and chilliness.
Headache localized in the frontal part and in the eyeballs. The movement of the eyeballs and pressure on them causes increased pain.
Weakness and severe muscle and joint pain.

There are mild and worn-out forms of flu. It is this category of patients that spreads the infection during epidemics and pandemics.

Upper respiratory tract flu symptoms and signs

Influenza viruses have a tropism for the epithelium of the upper respiratory tract. On examination, patients show redness of the soft palate and pharynx. In severe cases, nosebleeds and punctate hemorrhages in the soft palate are noted.

Figure: 7. In the photo there is an acute catarrhal sore throat. There is hyperemia in the area of \u200b\u200bthe lateral ridges, larynx and pharynx.

Symptoms and signs of influenza in severe cases

A severe course of the disease is indicated by an increase in the patient's body temperature to 40 ° C. The brain suffers, which is manifested by agitation, hallucinations and seizures. Meningeal symptoms appear - signs of inflammation of the pia mater. Vomiting and nosebleeds develop. There is a danger of death.

For express diagnostics of influenza in the reaction of immunofluorescence (RIF), a swab from the nasopharynx is used. The paired sera method is used for retrospective diagnosis of the disease.

Complications of influenza

Complications of influenza during epidemics of influenza make up 25 - 30%.

One of the most serious complications is infectious toxic shock, in which acute cardiovascular failure develops, pulmonary and cerebral edema, disseminated intravascular coagulation syndrome. With a fulminant form of influenza, an infectious-toxic shock develops on the first day of the disease.
Pneumonia (viral, bacterial or mixed) develops in 15 - 30% of cases. Viral pneumonia is especially difficult. The disease has a high mortality rate. Influenza viruses multiply in the epithelium of the upper respiratory tract and immediately begin to infect the epithelium of the trachea, then the bronchi and alveoli. On the way to the lung tissue, viruses mutate and antiviral drugs, which the patient accepts, are powerless. Without proper medical care, death occurs on the 3rd day. Proper treatment of influenza pneumonia is provided only in a well-equipped hospital. The reasons for the high mortality rate in influenza pneumonia are: late seeking medical help, self-medication and lack of vaccination.
Aseptic meningitis and meningoencephalitis.
Infectious-allergic myocarditis and pericarditis.
The syndrome of rhabdomyolysis develops, which is characterized by the destruction of muscle cells and the subsequent development of acute renal failure.

After influenza, 65% of patients have asthenic syndrome for several weeks, characterized by weakness, fatigue, headache, insomnia and emotional distress.

Vaccine prophylaxis is the foundation. Tamiflu, Ingavirin, Kagocel and Arbidol - drugs recommended for the treatment and prevention of influenza by the Ministry of Health of the Russian Federation. They are highly effective during the first 3 days of the disease. On the 4th day, their effectiveness decreases to 50%. Before taking these drugs, you must carefully read the instructions.

You can reduce the risk of spreading the flu and avoid getting sick by following simple hygiene rules, for which it is necessary:

Minimize contact with patients with influenza, do not come closer than a meter to them.
Do not attend public events during the flu period.
Wash your hands more often and wipe with alcohol-based solutions.
Wear a mask.
Do not touch your face, eyes and nose with dirty hands.

Figure: 8. Capsules and powder for the preparation of Tamiflu suspensions for the treatment and prevention of influenza in children from 1 year of age and adults. Possesses antiviral activity.

Figure: 9. Immunity stimulator Kagocel for the treatment and prevention of influenza in children from 3 years of age and adults and the antiviral drug Ingavirin.

Figure: ten. Antiviral agent Arbidol in tablets and Arbidol maximum in capsules. It is used for the treatment and prevention of influenza in children from 3 years of age and adults.

Influenza affects thousands of people every year. The economic damage from it is enormous. Preventive measures will help a person avoid the disease or weaken its manifestations. Adequate treatment can help avoid complications of the flu.

Read more about the treatment of influenza and its prevention in the article

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The hereditary information of the virus is contained in an RNA molecule packed in a double protein shell - a capsid. On the surface of the capsid are proteins involved in the penetration of the virus into the cell. These proteins are hemagglutinin-H and neuraminidase-N (see the photo of the influenza virus under a microscope). While the RNA of the virus remains almost unchanged, hemagglutinin and neuraminidase often change their structure.

Today there are 16 known hemagglutinin variants (H1, H2, ... H16) and 9 neuraminidase variants (N1, N2, ... N9). Each strain is characterized by a certain combination of these variants - a subtype. So, we get influenza viruses H1N1 (), H5N1 (avian), H3N2 (seasonal) and so on. It can be calculated that the theoretically possible number of subtypes is 144 (16x9). However, only 115 subtypes are known to date. Thus, it is possible that new influenza virus subtypes will appear in the future.

Human immune cells recognize the H- and N-molecules of the virion, and produce antibodies to them. If the same subtype re-enters the body, antibodies will provoke its destruction, and the disease will not manifest itself. If a person encounters another influenza virus, the immune system will not be able to fight it with the "old" antibodies.

The variability of the protein structures of this virus is the main reason for the high morbidity among the population, as well as the insufficient effectiveness of vaccination.

Influenza A virus has the same symptoms as B and C, however it is more volatile and therefore more likely to cause epidemics. Type B can cause local outbreaks of infection in children. Type C is the most conservative. It is believed that up to 10 years, all people have immunity to this virus. Thus, it cannot cause epidemics, and preschool children usually get sick with it.

Spread

ARVI ranks first in terms of spread among infectious diseases. In this case, the flu is the cause of about 15% of cases of ARVI.

Like all SARS, influenza is spread by airborne droplets. The only source of infection is a sick person (less often an animal). By coughing and sneezing, the patient disperses microparticles of mucus containing virions into the air.

You can get infected even when talking at a distance of several meters.

Particles of mucus also remain on surfaces, such as railings in vehicles, doorknobs, and so on. Patients with a mild form of the disease make a large contribution to the spread of infection.

At temperatures up to -4 C, virions can be stored for 2-3 weeks. At a temperature of 50 C, the influenza virus dies within a few minutes. Most quick way inactivation - the use of disinfectants (based on alcohol, chlorine).

History of influenza research

It turns out that this disease has been accompanying humanity for a very long time. Even Hippocrates (4th century BC) mentioned in his writings a disease, the symptoms of which are very similar to the flu. Naturally, the reasons for it were unknown then, and the word "flu" itself appeared much later. Until the 20th century, doctors believed that the causative agent of this disease was a bacterium. And only in 1933, when it was raging in Europe, was the causative virus isolated and discovered. It turned out to be type A flu. Type B was discovered somewhat later, in 1936, and type C in 1947.

Since then, we have learned a lot about this pathogen - its life cycle, biochemical composition, the sequence of nucleotides in RNA. However, there is still no remedy that could prevent or cure this disease with 100% efficiency.

Clinical picture

The disease occurs in the human body in several stages:

There are several degrees of flu severity:

Mild severity is characterized by the absence or weakness of intoxication symptoms. The head almost does not hurt, the body temperature is normal or slightly increased. Disturbed by superficial cough, redness of the throat, mucous membrane of the eyes. Light flow it can be observed in people who have encountered a strain that they have already had once, or in vaccinated people, if the vaccine contains not identical, but very similar viral particles.
The moderate form is most common. There is a classic clinical picture. The temperature on the first day of illness rises to 38-39 C, headache and muscle pain, weakness, and heavy sweating are troubling. The mucous membrane of the eyes and pharynx swells, turns red. Local symptoms appear at the end of the first - beginning of the second day. This is a cough, pharyngitis; runny nose is usually mild. If abdominal pains are concerned, it is not flu, but enterovirus (the so-called intestinal flu virus) or mixed infection. However, newer strains of influenza such as swine and avian influenza are often associated with stomach and intestinal symptoms such as vomiting and diarrhea. Therefore, with the simultaneous appearance of cough, fever and intestinal upset, it is worth consulting a doctor. Usually on the fourth day the fever disappears. If the flu proceeds without complications, it goes away within 5-10 days after the first symptoms appear.
A severe form requires hospitalization. Its symptoms are body temperature above 40 degrees, severe muscle and headache, pronounced local symptoms, convulsions, hallucinations and other nervous disorders. In addition, nosebleeds and punctate subcutaneous hemorrhages may be disturbing (since the virus can affect the blood coagulation system).
The hypertoxic form can lead to the death of the patient. Most often this occurs due to toxic effects on the brain in combination with disruption of the blood clotting system. Usually, the hypertoxic form is observed in people with other diseases - obesity, diabetes mellitus, alcoholism, hemophilia, etc.

Very often people have difficulty diagnosing influenza on their own. Indeed, the symptoms of this infection are very similar to those of other acute respiratory viral infections. Doctors recommend paying attention to some of the local features:

the face and mucous membranes swell;
swelling and redness of the conjunctiva of the eyes;
blue lips and tongue;
redness of the visible part of the pharynx and soft palate;
headache is localized in the temples, forehead, eye sockets;
stuffy nose, but mild runny nose;
dry, painful cough.

These symptoms will help you identify the disease at an early stage and go to the hospital in time.

Treatment

Symptomatic treatment for viral flu is as follows:

Bed rest in the acute period, in the catarrhal period - half-bed.
Fortified food, you can also take vitamin preparations.
Drink plenty of water - diuretic teas (for example, with raspberries), mineral water, tea with lemon, juices, etc.
For cough - bromhexine, bronchodilator.
With fever (from 38 degrees in children, from 38.5 C in adults) - antipyretic drugs. It is believed that the least side effects for paracetamol-based drugs.

However, the etiological treatment of influenza virus is a priority.

The following groups of drugs are distinguished here:

Interferon preparations - influenza, viferon, etc. Interferons are substances produced in the body to fight viral infections... Thus, these drugs mimic this process.
Interferon inducers are substances that stimulate the production of their own interferon in the human body. Amiksin has this effect.
Oseltamivir (also known as Tamiflu) is considered the most effective antiviral drug for influenza.

It should be noted that many antiviral drugs used for influenza (such as Arbidol, for example), despite advertising, have questionable effectiveness.

Antiviral drugs can also be used for prevention. Nevertheless, it is known that low doses of them are inactive, and high doses can have toxic effects. Doctors recommend using drugs for prevention only during periods of seasonal epidemics, no longer than 2 weeks.

Prevention

Naturally, it is better to prevent infection with the flu virus than to treat its effects. It is known that vaccination is the most effective preventive measure.

Vaccination helps prevent disease in 70-90% of cases.

Its success directly depends on how the subtype of the virus that entered the body matches the subtype used for the production of the vaccine. You also need to understand that it does not and cannot protect against infection with other ARVIs - adenovirus, rhinovirus, parainfluenza.

It is recommended to be vaccinated every year primarily for those people who have high risk severe course and development of complications. These are children, old people, patients with chronic diseases of the heart, blood vessels, lungs, a tendency to seizures, people with weakened immunity, as well as those who are forced to contact a large number of people due to the peculiarities of the profession (teachers, drivers, medical and social workers).