Bird flu: symptoms, description of the disease, why it is dangerous for humans

Flu

– an acute viral infection caused by the influenza virus.

There are 3 types of the virus - A, B and C. Types A and B annually cause the development of seasonal epidemics, type C is rare and does not cause epidemics. Influenza type A is divided into different subtypes (H1N1, H3N2, H5N1, H7N9). The letters indicate the types of proteins on the surface of the virus (H - hemagglutinins, N - neurominedase), and the number indicates the order of their discovery. With the help of these proteins, the virus attaches to human cells. These H and N proteins are constantly changing, resulting in a different virus. If the type B virus affects only humans, then the type A virus circulates among people and many animals (waterfowl and poultry, horses, pigs). Currently, only 2 subtypes of the A virus are spread from person to person - H1N1 (swine flu) and H3N2. In 2015, the bird flu virus (H7N9) was identified; people were infected with it from domestic chickens, while the chickens themselves did not get sick and the virus was not transmitted from person to person. The avian influenza virus was characterized by a severe course in children.

Seasonal outbreaks are typical for places with a temperate climate during the transition to winter. Apparently, a decrease in ambient temperature leads to a decrease in immunity and a weakening of the body’s defenses, which is a predisposing factor in the development of the epidemic.

Main route of infection

– airborne. The influenza virus attaches to the surface cells of the respiratory tract, penetrates them and multiplies, leading to death. Massive cell death leads to local inflammation of the airways, weakening their protective properties. All this causes secondary complications with the development of deadly pneumonia. When you cough and sneeze, millions of viruses spread into the air and infect people.

During an epidemic, there is a high chance of getting sick while in public places. You can also become infected through household contact; the patient’s secretions on the hands and household items (table, pens and pencils, handrails in transport, door handles, telephone handsets and other gadgets) are dangerous. The virus remains active on these objects for 2 hours. That is why the basic rules for preventing infection are:

1. Avoid crowded places during an epidemic;
2. Wash your hands, face, and blow your nose more often and thoroughly;
3. Use disposable disinfectant wipes;
4. Ventilate the room;
5. Wear individual disposable masks (it should be noted that the confined space they create can be a negative factor; it is recommended to replace masks every 4 hours)

Flu symptoms

Flu symptoms

are high temperature (
up to 38-39
), general weakness, lethargy, pain in muscles and joints. The so-called respiratory syndrome develops - coughing, sneezing, feeling of lack of air, sore throat. Symptoms of pneumonia (pneumonia) are rapid breathing (about 40 respiratory movements when the norm is 20), severe cough, shortness of breath, and blue discoloration of the skin. In these cases, hospitalization and inpatient treatment are recommended. To confirm pneumonia, an x-ray of the lungs is usually performed.

Flu symptoms usually last 7-10 days

, then pass on their own. Why most people have a mild form of the disease, and some have a severe form with the development of complications, scientists have not yet figured out.

Diagnosis is based on the presence of characteristic complaints (increase in temperature to 39 degrees and severe intoxication syndrome - general weakness, drowsiness, body aches, on the 2-3rd day respiratory syndrome - cough, runny nose) during the period of seasonal exacerbation. Laboratory diagnostics to determine the type of virus are not carried out in everyday life due to the lack of prognostic significance.

Bibliography

1. Methodological recommendations Flu in adults: diagnosis, treatment, methods and methods of nonspecific prevention https://www.pharmaclon.ru/
2. Influenza in adults: guidelines for diagnosis, treatment, specific and nonspecific prevention / edited by academician, professor A.G. Chuchalin, chief freelance infectious disease specialist of the Northwestern Federal District, prof. T.V. Sologub. - St. Petersburg: Publishing and printing complex "NP-Print", 2014. - 192 p. https://www.influenza.spb.ru/
3. Influenza and other acute respiratory diseases M.G. Shkadova, V.V. Kilessa, N.V. Zhukova Crimean Therapeutic Journal, 2011, No. 2 Shkadova M. G., Kilessa V. V., Zhukova N. V. Influenza and other acute respiratory diseases // Crimean Therapeutic Journal. 2011. No. 2 (17). https://cyberleninka.ru/article/

Flu treatment

It is advisable to adhere to home bed or semi-bed rest. This is especially true for “business” people who constantly work and prefer to endure the flu “on their feet.” Firstly, in doing so they infect their surroundings, and secondly, the chances of developing complications with further hospitalization increase significantly.

Drugs with proven antiviral activity against influenza are oseltamivir (Tamiflu) and zanamivir (Relenza). However, for their effective use, they should be taken in the first hours of the development of symptoms, maximum during the first 24 hours. The World Health Organization does not confirm the effectiveness of the domestic drug Arbidol and does not recommend its use as an antiviral agent.

The same can be said about a large group of immunostimulants and immunomodulators (cycloferon, amiksin, galavit, diucifon, imunofan, thymogen, viferon, kipferon, ribomunil, bronchomunal, oscillococcinum, etc.). Their effectiveness is zero and does not exceed the placebo effect. As a rule, all of them are not registered at all and are not used in European countries and the USA. Unfortunately, lubricating the nose with oxolinic ointment also does not protect us from the influenza virus.

The vast majority of people heal on their own at home within 5-10 days. Here you can remember the old saying: “If you treat the flu, it goes away within 7 days, if you don’t treat it, it will go away within a week.”

Thus, when the temperature rises above 38.0 degrees, it is recommended to give antipyretic drugs (paracetamol, ibuprofen). For children, there are forms of these drugs in rectal suppositories and powders.

For cough symptoms, drugs from the mucolytic group are used, which help thin and remove mucus. If you are bothered by a painful dry “barking” cough, you can use central antitussive drugs.

In general, in most cases of persistent cough, a symptom indicating the presence of bronchitis, in order to eliminate it and prevent the development of pneumonia, it is necessary to use penicillin or macrolide antibiotics. To do this, you need to consult a doctor.

What is the danger?

Bird flu has been diagnosed in all types of domestic birds: terns, parrots, quails, pheasants. All strains are capable of recombination, resulting in the formation of completely new, unexplored variations of the virus.

Often, when there is a massive mortality of poultry at poultry farms, and a diagnosis of avian influenza is established, laboratory tests reveal non-virulent strains of the virus. This indicates the serious importance of stress factors, existing infections (note: mycoplasmosis) and poor living conditions in the development of the disease.

Sources of the causative agent of classical bird plague:

• sick;
• recovered individuals (virus carriers).

The influenza virus is released through secretions and excreta; transmission route is airborne. You can bring it into the house with exchange containers, hatching eggs, and feed. In megacities, classic bird plague is carried by crows, jackdaws, pigeons, sparrows, rodents and cats. According to studies, virulent strains are more often diagnosed in short-lived birds.

When to call a doctor if you have the flu?

For children, the reason to call a doctor is frequent and difficult breathing, bluish skin tint, lethargy and drowsiness, refusal to drink and eat, repeated vomiting, high temperature (39 or more).

For adults – shortness of breath, worsening during the day, chest pain, repeated vomiting, severe weakness and dizziness, high fever.

In order for the efforts of doctors to be effective, you need to seek help from doctors in a timely manner, i.e. immediately when the above symptoms appear.

How the disease develops

There are 4 stages of development of classical fowl plague. The virus is primarily localized on the mucous membranes; no more than 4 hours pass from the moment it enters the bloodstream. Stages:

1. The first is the reproduction and increase in the concentration of the virus.
2. Second (viremia), the virus is easily detected in the blood.
3. Third, the production of antibodies, the pathogen does not multiply.
4. Fourth, the concentration of antibodies increases, immunity begins to form.

The pathogen destroys red blood cells. Virions are toxic, they secrete substances that are poisonous to the body, and this occurs most at stage 2. The likelihood of death at this time is high.

How to avoid getting the flu?

The most effective way to specifically prevent influenza is vaccination!!! Its safety and effectiveness have been confirmed by 50 years of use by progressive doctors around the world. 70-90% of those who got vaccinated in October-November (Influvac, Influenza) can rest easy during the seasonal epidemic; they will not get the flu. Even if the types of influenza virus in the vaccine do not match the type that caused the epidemic, the severity of the disease in the vaccinated person will be several times less, and the possibility of developing complications is sharply reduced.

WHO recommends that the following groups of people be vaccinated annually:

• pregnant women at any stage of pregnancy
• children from 6 months to 5 years
• seniors 65 years and older
• people with chronic illnesses
• healthcare workers

Summarizing all of the above, we can draw the following conclusions:

1. The most effective way to reduce morbidity and mortality from influenza is to get vaccinated annually
2. Immunostimulants and oxolinic ointment are ineffective against influenza
3. If the temperature rises above 38 degrees, antipyretic drugs should be given
4. You should call a doctor if: the temperature rises above 39.0 degrees, with a constant and debilitating cough, rapid and difficult breathing, shortness of breath, vomiting, dizziness, refusal to drink and eat in children.

What the experts say

According to Professor Anatoly Altstein from the Gamaleya Research Center for Epidemiology and Microbiology, it has happened more than once that bird flu was transmitted from person to person, but in all the cases that were described, the virus did not spread like an epidemic. “In the current case, it doesn’t look dangerous either,” says Altstein, “but there needs to be caution.” The expert positively assessed Vector’s development of a test system and vaccine against bird flu, but warned that, in any case, there is no reason to panic yet.

Advisor to the Director of the Research Institute of Influenza named after. A.A. Smorodintseva Lyudmila Tsybalova explains that avian flu is, first of all, dangerous for birds, and for those people who come into contact with sick animals - this usually happens at poultry farms or at processing industry enterprises working with poultry. At the same time, some types of influenza in birds themselves do not cause any special symptoms, but can be dangerous for humans. Therefore, if an outbreak of disease occurs in a factory, as a rule, all birds are destroyed. Avian influenza viruses, Tsybalova says, lead to diseases to a lesser extent in wild birds, which are often only carriers. The disease mainly affects domestic animals, which are less resistant to viruses.

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“The influenza virus is very fickle and susceptible to mutations, so it cannot be ruled out that several mutations will occur, and the virus will not only overcome the interspecies barrier, but will also begin to be transmitted from person to person,” says Tsybalova. The story is similar with the coronavirus, which is common among animals—cats, dogs, and mice suffer from it, but as a result of a series of mutations, it began to spread in the human environment.

According to Tsybalova, it is necessary to create libraries of vaccine strains in advance in order to be able to quickly develop mono-vaccines against specific strains of the avian influenza virus. The second option is vaccines that will be directed against all influenza A viruses that are transmitted to both humans and animals, Tsybalova notes. According to her, at the Research Institute of Influenza named after. A.A. Smorodintseva, together with the Institute of Bioengineering of the Federal Research Center “Fundamental Principles of Biotechnology” of the Russian Academy of Sciences, is developing recombinant protein vaccines that induce immunity to a wide range of influenza A viruses, and one of them has successfully passed the first stage of clinical trials. On the other hand, Tsybalova notes, not every mutation or set of mutations requires the development of a new vaccine, and the statement of readiness to begin developing a vaccine against H5N8 can be perceived as “more of a PR move.”

Director of the Eurasian Institute of Zoonotic Infections of the Federal Research Center for Fundamental and Translational Medicine, Professor Alexander Shestopalov, who has been researching influenza since 2002, doubts the evidence of the emergence of a new type of bird flu in humans. “There was an outbreak of avian influenza at the poultry farm, and the people who were involved in eliminating it could simply “inhale” the RNA of the virus (the macromolecule of the virus could be detected in the results of PCR tests that were carried out among employees. - Forbes ), but did they have this particular type of influenza? , that is, exactly H5N8, from the information that I heard in Anna Yuryevna Popova’s message it definitely does not follow,” says Shestopalov.

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It seemed strange to the expert that Vector would develop a special vaccine, since technologies for the production of influenza vaccines exist, and it is enough to replace the existing strains in the vaccine with the H5N8 strain and the vaccine can be produced. For example, in 2005-2006, when Russia first encountered highly pathogenic avian influenza of the H5 subtype, technologies for the production of vaccines based on these strains were developed. “Yes, in connection with the emergence of new strains of highly pathogenic avian influenza virus, it is necessary to adapt the existing technologies for the production of influenza vaccines,” Shestopalov is sure, “but there is no need to spend billions on this, as if we were all starting from scratch: there are serious developments from 2005-2006, when the vaccine was given to the H5N1 avian influenza outbreak.” According to him, the opportunity to use existing platforms to create a vaccine is probably available to [Rostec-owned] Microgen, [Ryazan Biopharmaceutical, Petrovax (owned).

Vector did not respond to Forbes’ request before the article was submitted.

Pathogenesis

When infected with the influenza virus, selective damage to the epithelium of the respiratory tract occurs. When viruses multiply in columnar epithelial cells, they gradually cause their degenerative changes. Host cells are used to build new viral particles. Since the replication of the H5III virus occurs not only through epithelial cells of the respiratory tract, but also through intestinal epithelial cells. Therefore, the disease can manifest itself not only as catarrhal syndrome, but also as damage to the gastrointestinal tract.

The influenza virus causes cytopathic, vasopathic and immunosuppressive pathomorphological changes. The causative agent of influenza, virus type A, is more stable in the environment than the human virus. It can survive in bird droppings for about 3 months, can tolerate low temperatures well, but dies under the influence of disinfectants. It is characterized by high contagiousness and variability.

Economic damage

The economic costs of eliminating the disease are very high. More than 4 billion euros were spent to eliminate the panzootic disease of 2005. This amount includes the slaughter of sick and healthy birds in the source of infection, the cost of quarantine, disinfection and vaccination.

In 2013, an outbreak of bird flu in China sickened more than 120 people, 32 of whom died. Tens of thousands of birds were destroyed.

Since December 2021, outbreaks of bird flu have been observed in Ukraine. The European Union has limited the import of poultry and poultry products from this country, and some states have imposed a ban on the supply of Ukrainian poultry products.

In Taiwan, more than 350 thousand birds have been killed since the beginning of 2021 in an attempt to stop panzootics. In addition, the country incurs huge costs to inform the population about the disease and take preventive measures.

In the Moscow region, since the beginning of 2021, more than 25 thousand birds have been destroyed at the Smena poultry farm, and more than 200 thousand farm animals will be slaughtered. Animals are also checked in neighboring areas - Shchelkovsky, Sergiev Posad, Tula region.

Diet

Diet for influenza, ARVI, colds

• Efficacy: therapeutic effect after 4-7 days
• Terms: 5-12 days
• Cost of products: 1500-1600 rubles per week

• The diet of a patient infected with this disease should be light, but at the same time rich in vitamins.
• It is extremely important to drink plenty of fluids to replenish fluid losses and prevent dehydration.
• You should eat in small portions, doing this 5-6 times a day.
• The menu should contain protein products (poultry, rabbit), fish, stewed and fresh vegetables, and fruits.
• It is recommended to drink fruit drinks and compotes, decoctions of dried fruits.

History of the study

The disease was first identified in Italy at the end of the 19th century. It quickly took over the country, killing a huge number of birds. At the same time, an Italian scientist identified the disease as a separate type, calling it exudative typhus, and in 1902 a conclusion was made about the viral origin of the disease. Together with migratory birds, the disease quickly spread to Europe, Asia, America and Africa.

Bird flu was first recorded in Russia in 1902. However, if at that time poultry was mainly affected by low-virulent influenza strains, in recent years the situation has worsened significantly, with more highly pathogenic strains appearing. Thus, the H5N1 avian influenza virus, brought from Asia by migratory birds, caused enormous economic damage in the Siberian regions of Russia. And it spread further, reaching Turkey. At the end of the twentieth century. For the first time, a case of human infection from a bird was registered, and by 2005, there were more than 100 cases of human infection, with half of those infected dying.

Prevention

There is currently no vaccine for this virus. Therefore, preventive measures boil down to following the following rules:

• Always cook poultry meat and eggs thoroughly.
• Destroy all infected birds on farms. At the same time, people who do this work must wear appropriate protective clothing.
• Conduct regular sanitary and epidemiological control over birds kept on farms and in private yards.
• Do not allow children to come into contact with potentially infected birds.
• If birds die on your farm, always notify your veterinarian.
• If cold symptoms occur after contact with birds, consult a doctor immediately.
• Always wash your hands thoroughly after handling birds.

Tests and diagnostics

• After the patient contacts the doctor, the specialist must determine whether the patient has had contact with potentially infected birds or traveled to regions with an increased risk of disease transmission.
• When listening to the patient, wheezing and harsh breathing are detected.
• An X-ray examination is carried out, where instantly spreading infiltration is determined.
• Laboratory tests are also carried out. A blood test demonstrates a decrease in lymphocytes , leukocytes , and platelets .
• An RT-PCR analysis is carried out, for which a swab is taken from the nose or throat.
• Sputum and endotracheal aspirate samples can also be taken for analysis.

If a case of avian influenza is confirmed or suspected during the diagnostic process, it is reported to the Centers for Disease Control and Prevention.

Virus sources and spread

Representatives of the UN Food and Agriculture Organization suggest that waterfowl and migratory birds play a significant role in the spread of avian influenza. Through their excrement, saliva or other secretions, the virus enters water bodies, plants, poultry houses and other places where poultry live. Depending on the type of influenza in birds, the disease can occur either in a mild form, causing deterioration in egg production and respiratory diseases, or in a fulminant form, systemically affecting internal organs and ending in the death of the individual within 24-74 hours.

The virus can enter the human body through direct contact with infected birds, in particular domestic ducks and chickens, or dead animals. Contact with feces, saliva, secretions or blood of sick birds, or consumption of contaminated water or food can also cause illness. Some types of the virus can be transmitted through dust or air.

Scientists say that today the infection is not transmitted from person to person.