Among the diseases of chickens, bird flu in chickens is the most dangerous. This disease is also called classical plague because of its high lethality. It brings big losses for farms and private farmsteads. The case of chickens is from 10 to 100% of the chicken population.

Avian influenza is the deadliest viral disease.

Wild birds are highly resistant to this virus and are only carriers of the disease. Waterfowl, especially ducks, are the most dangerous. For them, the flu does not pose any danger and passes without visible symptoms.

Bird flu is dangerous because the virus is constantly mutating, and its strains are rapidly updated. There are new modified forms of influenza, which makes it impossible to create vaccines against it. In sick birds, symptoms such as damage to the digestive organs and respiratory failure are observed.

Young animals are the first to be affected. This can be facilitated by inadequate feeding, transportation and overcrowded planting. In the future, the virus spreads to healthy chickens.

In the home, bird flu can be spread in the following ways:

• chickens that are sick or have had influenza excrete a lot of active virus with excretions;
• the virus can be transmitted through contaminated dishes, feeders and trays. Sources can be eggs and chicken feathers;
• Small rodents are also carriers of bird flu.

Scientists at Oxford University have been studying this problem for a long time. They proved that the mass death of poultry is due to the fact that protective immunity does not have time to develop in them due to their short lifespan. Therefore, the number of outbreaks of bird flu has increased so dramatically in recent years.

The reason for the mass death of chickens is low immunity

Forms of bird flu

It is known about the presence of 15 varieties of chicken flu. The H5N1 and H7N7 viruses are the most dangerous. They cause an acute and most dangerous disease in chickens. It takes a short period of time to damage the body of a bird. One hundred percent death of the chicken population occurs within 2 days.

The disease in a mild form goes away on its own and has no obvious symptoms. Egg production is slightly reduced and the condition of the feather worsens.

If chickens get sick with a more severe form of bird flu, then the characteristic symptoms can be recognized already during the first 20 hours. The duration of the incubation period can last from 3 to 5 days.

Avian influenza is characterized by acute, subacute and chronic forms. Subacute and chronic degree of the disease lasts from 10 to 25 days. Recovery occurs in 80% of cases. The likelihood of mass mortality at this stage is unlikely.

If an infection with a low pathogenic strain occurs, then the disease becomes chronic. Symptoms are subtle or completely absent.

Chickens are susceptible to 15 varieties of bird flu

Symptoms of bird flu

The main symptoms of acute avian influenza include the following:

• there is a sharp decrease in egg production;
• anorexia occurs, as sick birds refuse to eat;
• chickens have a depressed appearance, feathers are very ruffled;
• mucous tissues become inflamed. A thick mucus is released, which completely clogs the respiratory tract;
• heavy rales are heard, breathing becomes intermittent;
• there is an increase in temperature, it can reach 40-44⁰С;
• diarrhea appears, the litter is brown with a green tint;
• seizures begin, neurosis appears.

Bird flu primarily affects the nervous system of chickens. This is evidenced by symptoms such as:

• chickens suffer from discoordination of movement. They begin to stagger, cannot step on their feet, often fall;
• there is a curvature of the wings and neck, they acquire an unnatural position;
• no response to external stimuli;
• in sick individuals there is a strong thirst, and subsequent pulmonary edema leads to death.

The bird flu virus infects the nervous system and leads to pulmonary edema

Influenza subtype H5N1

For the avian influenza subtype H5N1, the most insidious and dangerous, the following signs are inherent:

• damage to the vascular system of birds occurs;
• sick chickens suffer from internal hemorrhages;
• blood circulation is disturbed;
• on the first day, cerebral edema occurs.

The alleged diagnosis is confirmed by a number of studies. H5N1 avian influenza exists if:

• avian influenza virus detected and identified;
• all subtypes of avian influenza identified;
• the presence of RNA (ribonucleic acid) has been proven.

There are antibodies to hemagglutinins characteristic of the H5 subtype, antibodies have no connection with vaccination.

It is possible to circulate several varieties of the virus at the same time. The causes of infection with avian influenza in farms are as follows:

• the infection could penetrate with feed;
• if contaminated equipment and inventory was used;
• if there was no disinfection of meat and egg chicken containers. It is carried out using bleach, hydrochloric acid, sodium hydroxide or phenol. They are able to quickly inactivate the virus.

Four stages of avian influenza

The reproduction of the virus occurs on the mucous tissues of the bird. It penetrates into the blood in a short time (4 hours), destroying red blood cells.

In its development in the body, the virus goes through four stages:

• in the first stage, the virus multiplies and accumulates in the body;
• the second stage or stage of virosemia, is characterized by the fact that the virus is easily determined in the blood of diseased chickens;
• in the third stage, viruses do not multiply, and the body begins to produce antibodies;
• at the last 4th stage, the accumulation of antibodies continues, and the body begins to resist the disease, i.e., immunity begins to develop.

Viruses are toxic and release substances poisonous to bird life at the stage of viremia. Therefore, the chicken case at this stage is maximum.

The virus acts by destroying red blood cells

Avian influenza is confirmed by autopsy of dead birds. There are a number of symptoms and signs that help identify the presence of the virus:

• catarrhal-hemorrhagic changes are found in the mucous membranes of the digestive system;
• all respiratory organs of the bird are affected, which swell strongly;
• the digestive system suffers, the work of the stomach and spleen is disturbed, which leads to a significant weight loss of the bird.

With the further development of the disease, the internal organs of chickens are not able to function normally.

The disease is diagnosed on the basis of the isolation of the strain of the influenza virus from the pathological material. Blood serum is analyzed at different stages of the disease. These symptoms indicate that the bird is sick with bird flu.

There is no cure for avian flu. All sick birds are killed to prevent further spread of the virus.

It is not recommended to eat the meat of diseased birds. Prevention of the disease is to limit the contact of poultry with wild birds.

If avian influenza is registered in the surrounding areas, then it is necessary to completely isolate the bird and keep it indoors for at least 21 days. The slightest symptoms and signs of the disease are checked by the veterinary service.

There is no cure for bird flu, so the sick bird is destroyed

To implement personal protection, you must follow the following tips, which are developed and recommended by WHO:

• contact of children with wild birds is prohibited;
• dead chickens are disposed of in specially designated places or burned;
• it is necessary to use a mask, respirator and gloves when disposing of the carcasses of sick birds. Mandatory treatment of the face and hands with soap at the end of work. Clothing must be treated with special disinfectants;
• it is forbidden to eat eggs and unchecked meat of a diseased bird;
• for storing meat and chicken eggs in the refrigerator should be separate boxes;
• having found a sick bird, it is necessary to immediately inform the veterinary service;
• if contacts have led to the appearance of acute respiratory diseases similar to influenza, then a doctor's consultation is necessary.

The mass death of chickens from bird flu brings great economic damage. Quarantine measures, veterinary and sanitary treatments are being organized, sick birds are being destroyed.

Source: http://SeloMoe.ru/kury/simptomyi-ptichego-grippa.html

How bird flu manifests itself in chickens, and is it dangerous for humans

When almost a century and a half ago, the Italian veterinarian Perroncito discovered a new strain of the A virus, related to the then known influenza pathogen, because of its rapid spread, he called it chicken plague.

But the discoverer did not fully understand its danger. Over the past century, three global influenza epidemics caused by birds have claimed tens of millions of lives. Currently, there are already a half dozen types of bird or chicken flu, two of which (H5N1 and H7N1) completely destroy the bird population.

The danger of the disease and methods of transmission

Bird flu is dangerous because of its ability to incessant and unpredictable modifications. And this nullifies all attempts to create vaccines against it.

Bird flu is transmitted through bedding, shared feeders and drinkers.

The disease affects poultry, especially chickens and turkeys, that come into contact with infected wild birds and rodents. The virus is often carried on the fur of a rat. Carriers of diseases, as a rule, do not suffer from them due to developed immunity.

Also, a dangerous virus is transmitted in the following ways:

• Through the droppings of infected birds and the objects they used (drinkers, feeders).
• Accidentally ending up on clothes, shoes, vehicles or other items that then fall into the bird's compound.
• Through the eggs and feathers of sick birds.
• From exotic birds that carry the infection, such as parrots.
• A person can also become infected by inhalation or contact with contaminated dust in the eyes.

Young birds, which have not yet had time to adapt to it, are especially affected by the flu. In Russia, the first outbreaks of a terrible disease were observed 10 years ago. For example, at the Novosibirsk poultry farms, at that time it carried away most of the chicken population.

More often, young chickens and chickens die from bird flu.

Forms of bird flu in chickens

There are 2 forms of bird flu. In a mild form, it is almost asymptomatic, passes quickly and does not require any intervention. In this case, the egg production of laying hens decreases slightly and their appearance deteriorates.

In case of a severe defeat, the disease develops rapidly, causing irreparable damage to poultry farms within two days. In the initial, latent stage of the disease (in the first 3-5 days), it is almost impossible to recognize it.

There are also acute, subacute and chronic forms of influenza. How does each of them manifest itself? The symptoms of the acute form will be discussed below. The subacute form lasts from a week to three with the same symptoms as in the acute form, but not so pronounced. It is characterized by a mass recovery of a sick bird.

A weakly pathogenic variety of the virus leads to a chronic disease. In this case, the symptoms are blurred or indistinguishable.

There are acute and chronic forms of bird flu in chickens,

There are two possible outcomes of such a disease:

• Infected chickens develop antibodies to the infection.
• With the onset of adverse conditions, the disease can go into an acute form.

Symptoms of acute bird flu

The first signs of the disease in severe form are noticeable after a few hours.

These include:

• Inflammation of the mucosa with the release of a viscous substrate that completely blocks the airways of birds. From the breath becomes heavy, hoarse.
• The appearance and behavior of birds is changing, they sit, ruffled, with ruffled feathers.
• At the same time, sick birds do not eat anything, but drink a lot.
• The temperature rises to a mark of 40 degrees and above.
• The color of the litter becomes green-brown.
• Coordination of movements in laying hens is upset: when walking, they stagger and often fall. There is an unnatural posture, tilting and rotation of the head. Birds do not respond to external stimuli.
• The picture of the disease is completed by convulsions, neurosis.
• And because of the poisoning of the body with toxins, the comb and earrings turn black.

Avian flu symptoms in chickens Sick chicken looks disheveled Earrings and comb blacken with bird flu

The egg production of diseased chickens is significantly reduced. At the last stage of the disease, the temperature drops sharply to 30 degrees.

Influenza subtype H5N1

The most terrible subtype of H5N1 chicken flu affects the vascular system of birds, which is accompanied by extensive internal hemorrhages (cerebral, gastric, intestinal). For people, it is dangerous because due to severe pathologies in the lungs, aggravated by complications, mortality reaches three-quarters of cases.

This strain does not respond to treatment with interferon and rimantadine. And his ability to modify is very high. As a result, experts are afraid of possible mutations of the virus, leading to infection of people from each other by airborne droplets.

How to determine the presence of this flu strain in laying hens? Such a diagnosis can only be confirmed by laboratory methods, examining pathological material.

The H5N1 influenza virus is affected by ether and chloroform.

Attention! This virus is still vulnerable. It is negatively affected by chloroform and ether. And at temperatures above 70 degrees, it is destroyed in a couple of minutes.

Four stages of avian influenza

When chickens are infected, the pathogen actively reproduces on the mucous membranes and, quickly entering the bloodstream, leads to the breakdown of red blood cells.

In this case, 4 stages of the disease are observed:

• At the initial stage, the virus multiplies.
• The second stage is characterized by its penetration into the blood.
• Further, the body, producing antibodies, inhibits the reproduction of pathogens.
• At the end of the process, the accumulated antibodies counteract the viruses, forming immunity to them.

But when infected with highly pathogenic viruses, the toxins actively released by them in the second stage of the disease cause poisoning of the body. This leads the laying hens to death long before the connection of its protective forces.

Bird flu occurs in 4 stages in chickens.

What to do with a sick bird

The bird flu virus mutates so quickly that a universal vaccine against it has not yet been created. Therefore, when symptoms of the disease appear in an acute form, diseased birds should be immediately destroyed.

In this case, the entire chicken coop is subject to quarantine, namely:

• Affected body parts of dead laying hens should be sent to a special laboratory for examination without delay.
• Birds that have come into contact with them must also be destroyed to prevent the spread of infection.

Influenza Diagnosis and Prevention

A dangerous disease can be diagnosed by laboratory tests of the blood of infected birds and examination of the remains of dead birds. In the latter, even to the naked eye, extensive hemorrhages of organs, edema of the lungs and digestive organs are visible. Sick birds quickly lose weight, the functioning of all their organs is disturbed.

If avian influenza is detected in a neighboring area, then for the purposes of prevention, it is necessary to immediately close poultry in an isolated room for at least three weeks.

During influenza outbreaks, healthy birds should be moved to a quarantine facility.

How to protect chickens and people from a dangerous disease?

To do this, you should immediately:

• In order to avoid the transfer of infectious agents by wild birds, place all kinds of repellents around the yard.
• Conduct daily disinfection of the poultry house and all bird care items with 3% hot preparations of technical soda or chloramine.
• Treat bird perches and nests with slaked lime twice with a two-hour break.
• People caring for the poultry house need to administer interferon and take other antiviral agents.
• And children, the elderly and those who suffer from heart or lung diseases should completely avoid contact with any birds.

How to protect chickens in the backyard from a possible disease in any form? Firstly, laying hens purchased somewhere should not be immediately released into a common chicken coop. You have to watch them first. Secondly, after visiting someone else's farm, you need to wash the clothes in which you were there. Thirdly, a suspicious bird must be immediately separated from relatives and examined.

Laying hens purchased anywhere should not be immediately released into a common chicken coop.

In our country, fortunately, avian influenza is extremely rare. But when traveling abroad (especially to the Asian region or other potentially dangerous areas), it is necessary to remember the safety measures when dealing with any birds.

Important! The danger of bird flu lies in the fact that while an effective fight against an insidious disease is still possible, it proceeds almost imperceptibly. Its symptoms manifest themselves in the stage of a catastrophic increase in pathological changes in the body of birds. Therefore, it is precisely measures that prevent influenza that should be given special attention.

Methods of treatment and vaccinations

Anyone involved in poultry breeding needs to know that there are no effective methods of treating birds for chicken flu yet. Since the virus that causes the disease is constantly changing, bird flu shots may not be effective. A vaccine developed to combat one species is completely useless for another.

Bird flu shots often don't work.

If the case of the appearance of bird flu in the farmstead is laboratory confirmed, then all birds are disposed of. The same measures are taken for all poultry products.

The human immune system is also not adapted to fight the bird flu. When in contact with a sick bird, the likelihood of infection is high. This type of disease is severe and very dangerous for human life.

The hidden period lasts up to 8 days. At an early stage, treatment with antiviral drugs with some therapeutic effect is possible. So far, no drug has been developed that can kill the bird flu virus.

Attention! All therapeutic measures for this disease are effective only no later than the sixth day from the onset of the first symptoms of influenza.

To protect yourself from a dangerous infection, WHO recommends:

Dead and sick birds must be destroyed in isolated areas.

• Do not allow children to play with wild birds.
• All dead and sick in the acute form of birds must be destroyed in isolated areas.
• Disposal must be carried out using all personal protective equipment that completely covers the body.
• After that, hands, face, clothes and shoes must be disinfected.
• Meat and eggs of a dubious type should not be eaten.
• In the refrigerator, store poultry products separately from others.
• Every case of bird disease must be reported to the veterinary authorities.
• If you get flu after contact with a bird, you should seek medical help.

Can you get bird flu?

Influenza subtype A, which causes diseases in birds, is also dangerous for humans. Infection occurs through direct contact with birds carrying this virus, their feces or objects that they constantly touch.

It is known that the virus dies from high temperature. Therefore, when heat-treating poultry meat for more than an hour, it is not dangerous to eat it. Eggs with an admixture of blood cannot be eaten. Eggs that have not changed color should be boiled for at least ten minutes. Before this, they should be washed to get rid of the infection from the shell. Raw eggs are very dangerous.

Source: http://ferma-nasele.ru/ptichij-gripp-u-kur.html

bird flu symptoms in chickens

To date, there are a large number of infectious diseases that domestic chickens suffer from. The most dangerous and well-known is the bird flu with the H5N1 virus. For the first time, the disease was introduced in the 90s, when the virus was detected in many countries, where it caused serious damage to both industrial and private poultry farming.

Despite the fact that today there are good drugs, the disease continues to be classified as dangerous.

Why is bird flu so bad?

The greatest danger lies in the constant variability or mutation of the virus, as well as in the rapid renewal of strains. The creation of a vaccine becomes impossible due to the emergence of new modified forms of influenza. If we talk about the symptoms, then first of all the digestive system is affected and breathing is disturbed.

Most often, young birds suffer from influenza. Side effects can be a poor diet, the transfer of birds from one farm to another, and non-compliance with maintenance standards. Then the virus begins to spread to the rest of the livestock.

On a home farm, H5N1 is distributed as follows:

• the active virus is excreted with excrement from a sick or already ill bird;
• infected inventory, feed and water containers can also become a source of spread, the same applies to egg products and feathers;
• Mice and rats can spread bird flu.

This problem was studied by scientists who came to the conclusion that the bird is dying en masse due to the immune system, which cannot develop protection - this is due to the short life span of chickens. It is because of this that the epidemic breaks out quite often.

Vaccination

Symptoms

The biggest problem with this disease is that it has practically no symptoms, and it is possible to determine that the bird is sick only at the last stage - this is typical for most strains.

In fact, chickens can get sick in a mild or severe form, and an acute manifestation has very obvious signs. The light form is transient, and often does not even require the intervention of the owner. Here you can see the following signs:

• the quality of the feather cover is deteriorating;
• egg productivity decreases;
• the bird becomes lethargic.

The severe type of flow is more dangerous and ends in death. But there are a fairly large number of manifestations by which the disease can be recognized. Initially, the nervous system is affected, and the following deviations can be noticed:

• impaired coordination of movements;
• the cervical region and wings are bent;
• no response to irritating factors;
• the temperature rises;
• the bird refuses to feed;
• often drinks;
• lungs swell.

Such symptoms are primary and can affect the entire livestock in a few hours. After some time, you can notice a deterioration in the condition, which is characterized by other signs. Here the owner must show maximum attention so that the symptoms do not go unnoticed:

• the feather cover is ruffled;
• scallop with earrings turn black;
• wheezing is heard in the breath;
• indigestion;
• convulsions;
• emergence of a neurosis.

Then the vascular system is affected, and therefore there may be a strong hemorrhage. The brain swells within 24 hours.

One of the manifestations of bird flu

What you need to know about treatment

To date, despite all the efforts of scientists, it has not been possible to achieve any shift in the treatment of avian influenza. There are no vaccines or other medicines.

In this regard, all diseased livestock, as well as the rest of the poultry that had contact with diseased individuals, are sent for slaughter to prevent the spread of the virus.

Meat products should not be consumed by humans.

Finding a cure is very difficult, and there is a reason for this, which is that H5N1 spreads and mutates extremely rapidly. Therefore, the creation of a vaccine is almost impossible.

Bird flu is also dangerous because it is constantly changing, so the existing vaccine is likely to be absolutely useless for treating sick livestock the very next day.

This state of affairs is little consolation for the owners, but scientists do not give up and try to defeat the insidious disease. Among modern drugs there are those that suppress the harmful effects of the virus on the chicken body. For the treatment of each strain, you need to use your own drug and carry out such activities strictly under veterinary control.

What you need to know about prevention

Based on the foregoing, it becomes clear that bird flu is a dangerous and insidious disease, from which no chicken owner is immune. But you should not raise a strong panic, farmers should know that there are measures that can protect birds from the disease, or rather, minimize the risk of an epidemic.

It is important not to forget about the existing preventive measures:

• if an unfavorable situation with bird flu is declared in the area, it is necessary to isolate your birds from possible contacts with wild relatives;
• poultry should not walk in places where it can meet wild birds (for a period of 3 months or more);
• young animals should receive eggs as feed only from their own hens;
• all livestock should drink vitamin complexes;
• medicines used to treat sinusitis can be given as another preventive measure.

Source: https://fermers.ru/pticevodstvo/kury/ptichiy-grip

Bird flu. – Veterinary Service of the Vladimir Region

bird flu- (Grippus avium; highly pathogenic avian influenza, classical avian plague, chicken flu A, exudative typhus, Dutch chicken plague) is a highly contagious, acute viral disease that affects agricultural, synanthropic and wild birds, affecting the respiratory and gastrointestinal tracts.

Avian influenza can occur in the form of epizootics, causing massive coverage of livestock and having a wide distribution - district, region, country.

Historical reference. The disease was first described in Italy in 1880. Perronchito, who differentiated it from cholera of birds and called it exudative typhus of chickens. The most severe epizootic occurred in 1925. in the north of the country, during which 200,000 chickens died.

Subsequently, the disease spread to Austria, Germany, Sweden, Czechoslovakia and Romania. The disease was found in Asia, South and North America, Africa. Influenza was first brought to Russia in 1902. The viral nature of the virus was established by the Italian scientist Gentania in 1902.

At present, avian influenza in the form of classical plague caused by subtypes of the virus with low virulence is rare, in the form of periodic epizootic outbreaks.

Since the beginning of the 21st century, outbreaks of highly pathogenic avian influenza have begun to be recorded in many countries of the world as a result of the spread of influenza by migratory birds from Southeast Asia.

A highly pathogenic strain of the H5N1 virus was brought to Russia by wild migratory and waterfowl in 2005, when outbreaks of bird flu among domestic and wild animals were observed in Novosibirsk, Omsk, Tyumen, Kurgan, Chelyabinsk regions and Altai Territory. Then the "bird" flu reached Kalmykia, the Tula region, Turkey and Romania.

Economic damage from avian influenza is extremely high and is associated with the mass death of diseased birds, the costs of strict quarantine and veterinary and sanitary measures, including the destruction of sick birds. For example, the panzootic of bird flu in the world in 2005 caused material damage, which is estimated at 4 billion. Euro.

The causative agent of the disease– The RNA-containing virus belongs to the orthomyxovirus family, which is divided into three serological types: A, B and C. Type A viruses cause disease in animals and humans. The size of viral particles is 80-120nµ.

Influenza viruses, based on typing for the main antigens (surface proteins) - hemagglutinin (H) and neuraminidase (N), are classified into 15 and 7 subtypes, respectively. All of them have a certain relationship, but different serotypes cause diseases in different animal species.

For birds, the most pathogenic viruses are the H5 and H7 subtypes, which have the molecular biological characteristics of highly pathogenic viruses. The H5N1 virus is of greatest concern due to its possible danger to humans.

In birds, the virus induces the production of virus-neutralizing and complement-fixing antibodies.

The resistance of the virus in the external environment varies depending on the serotype. The virus is sensitive to ether, chloroform, heat and acid (pH 3.0).

At a temperature of 55°C, it is inactivated within one hour, at 60°C in 10 minutes, at 65-70°C in 2-5 minutes. When deep frozen (temperature -70°C) in meat, the virus remains virulent for more than 300 days.

Drying the substrate containing the virus preserves it.

Common disinfectants: bleach, sodium hydroxide, phenol, hydrochloric acid, carbolic acid and others quickly inactivate the virus.

epizootology. Influenza is recorded in many species of domestic and wild birds. The pathogenicity of the virus is not limited to the bird species from which it was isolated.

The Aj subtype virus has been isolated from chickens, turkeys, pigeons, ducks, and geese, while being pathogenic for rabbits, mice, guinea pigs, and humans, who develop atypical pneumonia in the event of complications.

Among wild and domestic birds, several antigenic varieties of the virus, characteristic of humans, birds and domestic animals, can simultaneously circulate. Stress reactions that occur in birds during their long flights and changing climatic conditions lead to an exacerbation of the infection.

In industrial-type farms, the introduction of the pathogen with feed, equipment, inventory plays a certain role in the appearance of the disease, while non-disinfected meat and egg containers are of particular danger.

The first cases of the disease, as a rule, are recorded in chickens and adult weakened birds against the background of their inadequate feeding, transportation, and overcrowding. The passage of the virus through the weakened body of chickens increases its virulence and contributes to the subsequent disease of the bird, which is kept under normal conditions.

All susceptible birds on the farm will usually recover from influenza within 30-40 days. This is due to the high contagiousness of the virus and the high concentration of birds in poultry houses.

The source of the causative agent of infection is a sick bird (within 2 months). Influenza virus causes disease in birds by respiratory, oral, intraperitoneal, subcutaneous and intramuscular infection.

In industrial enterprises with a cellular system for keeping poultry, the aerogenic route, as well as the alimentary one (transmission with drinking water), is of primary importance in the spread of the pathogen. From the body of a sick bird, the virus is excreted with excrement, secretions, droppings, hatching eggs.

Influenza virus transmission within poultry farms can be carried out by rodents, cats, and especially free-living wild birds entering or nesting in poultry houses.

The presence of virus-carrying chickens maintains an epizootic focus in the farm during the reproduction of a new population of susceptible birds, which, during rearing, falls ill and maintains stationary trouble. The incidence of poultry varies from 80 to 100%, mortality from 10 to 90%, depending on the virulence of the virus and the conditions of the birds.

In dysfunctional farms, influenza in chickens and hens is often complicated by pathogens of respiratory mycoplasmosis, infectious laryngotracheitis, and colisepticemia. An adult bird loses its egg productivity by 40-60% within 2 months after a disease.

A bird after recovering from influenza partially or completely loses immunity against Newcastle disease, infectious laryngotracheitis, bronchitis, and smallpox.

Pathogenesis. Depending on the virulence, tropism of the virus, the natural resistance of the bird, a generalized or respiratory form of the disease develops.

As a result of the virus entering the mucous membranes of the respiratory tract, it begins to actively multiply and penetrates into the circulatory system. All this happens within 4-12 hours. The virus is found in large quantities in the blood serum, as well as in erythrocytes.

In the development of the disease, it is customary to distinguish four phases: active reproduction of the virus and its accumulation in parenchymal organs, viremia - the virus in this phase can be detected in the blood, then the process of synthesizing antibodies begins, which indicates the cessation of further reproduction of the virus.

The last stage is accompanied by the active formation of antibodies and the formation of immunity in the bird.

Based on the fact that the virus releases toxic products in the course of its life activity, intoxication and death of the bird occur in the bird in the stage of viremia. This usually occurs in the acute course of the disease.

All highly virulent strains of the virus, regardless of belonging to a particular subtype, cause a generalized form of infection in birds.

With avian influenza caused by subtype A, hypoplasia of lymphoid organs, lymphocytopenia and suppression of protective mechanisms occur, which contributes to viremia and virus replication in the cells of various organs and tissues.

Due to the violation of the porosity of the walls of blood vessels and the violation of hemodynamics in a sick bird, the phenomena of hemorrhagic diathesis are noted.

Clinical picture. The incubation period is 3-5 days. Influenza can occur acutely, subacutely and chronically.

In an acute course, the bird refuses to feed (anorexia), the plumage becomes disheveled, the eyes are closed, the head is lowered, the chickens lose their egg production.

Visible mucous membranes are hyperemic and edematous, in a separate sick bird a viscous mucous exudate flows out of a slightly ajar beak, the nasal openings are sealed with inflammatory exudate.

In some sick chickens, swelling of the front part of the earrings is noted due to congestion and intoxication of the body. The comb and earrings are dark purple. Breathing becomes rapid and hoarse, body temperature rises to 44 ° C, and before the case drops to 30 ° C. If the disease in chickens is caused by highly pathogenic influenza viruses, then as a rule 100% of chickens die.

Subacute and chronic influenza lasts from 10 to 25 days; while the outcome of the disease depends on the resistance of the diseased bird. Mortality reaches 5-20%.

With this form of flu, a sick bird, along with respiratory symptoms, develops diarrhea, the litter becomes liquid, colored brown-green.

In addition to the above signs, the sick bird has ataxia, convulsions, necrosis, arena movements, tonic-clonic convulsions of the muscles of the neck and wings in the preagonal stage.

In cases of infection with low-pathogenic strains, cases of a chronic course of the disease without pronounced clinical signs are possible.

Pathological changes. Depending on the course of the disease, pathological changes vary widely. The most typical sign of influenza is a picture of hemorrhagic diathesis, accompanied by subcutaneous edema in the pharynx, larynx, neck, chest, legs, which contain gelatinous exudate.

These edema in birds occur as a result of dysfunction of the circulatory organs. There are both massive and single hemorrhages under the skin, in muscles, in parenchymal organs and mucous membranes; in laying hens - hemorrhages in the ovary and oviduct.

Permanent pathological signs of influenza are gastroenteritis, bronchitis, pericarditis, peritonitis, aerosaculitis, pulmonary edema, congestion in the internal organs.

Pathological changes in the brain are especially characteristic of influenza: hemorrhagic meningitis, diffuse hemorrhages, foci of edema in the softening of the medulla.

Histological examination of birds that died on the 3-4th day of the disease, along with stasis and hemorrhages, we find degenerative changes in neurons and multiple areactive necrobiotic foci in the gray and white matter of the brain.

Diagnosis. Based on the epizootic features of the course of the disease, characteristic acute clinical signs of respiratory disease and pathological changes, a presumptive diagnosis can be made. To make a final diagnosis, it is necessary to conduct a complex of laboratory virological studies.

Pathological material (liver, lungs, brain, etc.) from birds that have died in the acute stage of the disease is sent to the laboratory. The pathological material must be fresh, it can be frozen to -60°C in order to preserve the virus or stored in a 50% glycerol solution. For serological studies, paired blood sera are taken from chickens at different periods of the disease.

In the laboratory, methods for infecting chicken embryos are used to isolate the virus, and RHA, RTGA and RSK are used to identify the isolated virus. A biological sample is placed on chickens 60-120 days old.
For retrospective diagnosis, RTGA, RDP, ELISA and PCR are used.

The diagnosis of avian influenza is confirmed if:

• a highly pathogenic virus has been isolated and identified;
• isolated and identified any virus subtype H5 or H7;
• the presence of ribonucleic acid (RNA) specific for a highly pathogenic virus of any subtype or RNA of viruses of subtypes H5 or H7, any level of pathogenicity in samples of pathological material was established;
• antibodies to hemagglutinins of the H5 and H7 subtypes have been detected when it is reliably known that they are not associated with vaccination.

Differential Diagnosis. The generalized septicemic form of influenza is differentiable from Newcastle disease. Respiratory form - from infectious bronchitis, mycoplasmosis, laryngotrtacheitis and other respiratory diseases of birds.

Avian influenza, unlike Newcastle disease, affects all types of birds at any age and causes pronounced edema, catarrhal-hemorrhagic enteritis.

The respiratory form of influenza is characterized by a predominant lesion of the upper respiratory tract, all types of birds fall ill, and with infectious bronchitis - only birds of the chicken order.

Respiratory mycoplasmosis of chickens and infectious sinusitis of turkeys are characterized by a chronic course of the disease, the absence of acute inflammatory processes and the development of fibrinous-diphtheritic aerosaculitis.

Immunity and specific prophylaxis. An ill bird acquires non-sterile immunity, which lasts up to 6 months. For the prevention of highly pathogenic avian influenza in Russia, inactivated vaccines are used as the most epidemiologically safe.

For specific prophylaxis, inactivated aluminum hydroxide hydroxylamine embryonic type A vaccine, liquid and dry inactivated vaccines against avian influenza are used. Vaccines are administered intramuscularly, inactivated - twice with an interval of 14 days. For preventive purposes, only clinically healthy birds (chickens, ducks, turkeys) are vaccinated in threatened farms.

14-21 days after vaccination, the bird acquires intense immunity lasting up to 6 months.

Prevention

Now everyone is talking about bird flu. But no one can explain what it is. But in connection with the threat of its spread, it is important for everyone to know the nature and symptoms of this disease.

Is fever, runny nose, cough, pain in the throat, bronchi, lungs characteristic of this disease? Or maybe a stomach ache or a headache? Do avian flu survivors develop immunity?

Z. Zheleznyakov, Kislovodsk, Stavropol Territory

TO How do humans get avian flu?

The danger is the consumption of meat and eggs of sick birds without sufficient heat treatment. Dangerous discharge of infected birds. Getting on plants, in air, water, they are capable to infect the person.

The bird flu virus tolerates sub-zero temperatures well, but does not withstand heating to a temperature of plus 70 ° C and dies in a few minutes. To disinfect objects with which the bird carcass came into contact, they must be scalded.

Is there a vaccine for bird flu?

There is no vaccine yet, but one is under development. In addition, people do not need it yet, since the flu does not pass from person to person. In Turkey, they are infected for one reason: people and poultry often live in the same room. What do Turkish doctors offer to residents of this country now? Strengthen immunity and take antiviral drugs such as Arbidol, Remantadin, Algirem, Interferon (Grippferon). For the treatment of bird flu, only preparations containing salicylic acid are contraindicated.

Is it safe to eat chicken meat?

In areas where bird flu is not detected, poultry meat and eggs do not pose a danger. Scientists say that the causative agent of the bird flu virus lives in the intestines of a sick bird, and not in meat. The risk group includes people who are in direct contact with sick birds, such as workers in poultry farms.

If the meat of sick birds is safe after heat treatment, why are birds not only slaughtered in Turkey, but then burned?

In sick birds, the cloaca contains a huge amount of the bird flu virus, so it is dangerous to butcher sick birds. Even when slaughtering and butchering healthy birds, precautions must be taken: allocate a separate place and tools for this, use protective gloves and goggles. And after cutting the birds, treat all items contaminated with feces and blood, bleach or other disinfectant solutions. When working with carcasses, eating is prohibited. Gloves should not be removed until work is completed, and then hands should be washed with soap and water. As you can see, there are a lot of gimps, so the carcass is burned without processing.

How dangerous is the avian influenza A (H5N1) virus?

This virus can quickly and deeply affect the lungs, causing severe pneumonia, pulmonary edema, respiratory failure, which requires immediate mechanical ventilation. Bird flu also affects other human organs: kidneys, liver, blood-forming organs.

So far, there is no evidence of transmission of the avian influenza virus from a sick person to other people. But the fact that a virus that used to infect only birds has now acquired the ability to infect humans and other mammals is evidence that it is mutating, and so rapidly that at any moment the situation could arise when this virus will be transmitted from person to person.

How can you tell if a person has avian flu?

The disease manifests itself as a severe respiratory disease, bronchitis and pneumonia, fever and diarrhea. From infection to the first signs of the disease can take about a week.

Usually, the disease of bird flu begins acutely with chills, fever up to 38 ° C and above, muscle and headaches, and sore throat. Possible watery loose stools and repeated vomiting. The condition is rapidly deteriorating. After 2-3 days, a wet cough appears, often with an admixture of blood, shortness of breath. Breathing becomes hard, with wheezing. Then there may be difficulty in breathing caused by pulmonary edema.

In addition, damage to the liver and kidneys is noted, and a third of patients develop renal failure. Cerebral edema, acute panencephalitis, toxic shock, collapse are possible.

What symptoms appear in birds with influenza?

The most terrible virus A (H5N1) can be in birds, which, being carriers of the virus, remain outwardly healthy. Wild birds in this state are even able to make long-distance flights.

Clinical signs of bird flu:

* in wild ducks: unusual behavior, movement in a circle, torsion of the head, lack of reaction to the environment, then death;

* in geese and ducks (domestic): nervous phenomena - discoordination of movements, swimming in a circle, throwing back the head, rotational movement of the head with shaking, curvature of the neck, lack of response to external stimuli, refusal of food and water, depression. Respiratory symptoms - sinusitis, nasal discharge. Conjunctivitis, corneal clouding and blindness;

* in chickens: in young animals - a fulminant course in the absence of any signs. In adult chickens, nervous signs are less pronounced than in waterfowl. Some throw back their heads, there is an increase in body temperature, depression, ruffled plumage. The hen refuses to feed. There is cyanosis of the skin, especially in the area of ​​​​the eyes, legs and abdomen, swelling and blackening of the crest and earrings. Diarrhea, yellow-green feces are observed. Older chickens die more often.

What tests are needed to determine if a person has avian influenza?

For diagnosis, blood and a swab from the nose are taken. After 24 hours, a diagnosis can be made. In all regions of Russia, central infectious diseases hospitals use these methods. How to protect poultry from bird flu?

Domestic birds can become infected from any wild birds, even if they look healthy, and also through water, feed, grass, and any objects contaminated by their feces. Therefore, in private backyards, it is necessary to isolate places for keeping and walking poultry, as well as for storing feed and water, in order to avoid any contact with wild birds and their secretions. Free range poultry is currently dangerous. All sick or dead birds should be examined by the veterinary service for the presence of the virus.

Is it possible to infect humans with avian influenza through bird eggs?

Theoretically possible, although such cases have not been registered so far. When eating eggs, keep in mind that the flu virus is located on the surface of the shell of a sick bird, it is not inside the egg. Therefore, after buying eggs in the market or in a store, before preparing food from them or simply storing them in the refrigerator, it is useful to pour boiling water over them.

D. N. Yasin, infectious disease specialist

(H5N1) is a type of influenza virus that infects birds and can be transmitted from them to humans. Transmission of the disease occurs mainly by the fecal-oral route.

Historical reference

Avian influenza was first described in Italy in 1880. At the beginning of the 21st century, the disease spread through migratory birds from Southeast Asia to other countries such as Austria, Germany, Sweden, Czechoslovakia and Romania, Asia, South and North America, Africa. Avian influenza was discovered in Russia in 2005, it was introduced by wild migratory birds and outbreaks of the disease did not bypass the Novosibirsk, Omsk, Tyumen, Kurgan, Chelyabinsk regions and Altai Territory. Kalmykia, the Tula region, Türkiye and Romania were next affected by the virus.

The first bird flu virus in humans was recorded in 1997 in Hong Kong.

What is the danger of the disease

This type of flu is extremely dangerous for humans, the microorganisms are very contagious and cause serious damage to the lungs, the virus can affect the liver, kidneys, and brain. In addition, it is insensitive to interferon drugs, "Remantadine" and has a tendency to mutate, which makes it even more dangerous. Mortality from the disease is quite high and amounts to 50-80%.

How is bird flu different from regular flu?

Symptoms in humans initially resemble those of the common flu. There is a runny nose, cough, body temperature is elevated, the person becomes weak and lethargic. But the consequences of the disease are very severe, most cases end in death.

Therefore, if at least one bird falls ill on the farm, the entire livestock is destroyed in order to avoid serious consequences.

Transmission routes

The source of infection is wild waterfowl. They themselves do not get sick. Being in reservoirs with stagnant water, birds with feces leave a virus there, which infects waterfowl through the water, and then the rest that are on the farm.

The virus is transmitted to humans by airborne droplets. When poultry coughs, droplets of mucus or saliva are released. Inhaling them, a person becomes infected. It is possible to transmit the virus by contact, through touching objects on which the discharge of a sick bird remains.

The virus is able to survive for many years at temperatures below minus 70 ° C, which means it can be preserved in frozen meat. The past is safe, the virus dies at +70 ° C, in addition, it does not withstand repeated repeated freezing (more than 5 times).

A high risk of catching the virus is among people working on poultry farms, among rural residents who breed poultry. Also at risk are children, pregnant women and the elderly.

Main features

Y can take two different forms. The first option does not have serious consequences. A bird that is sick stops rushing, she has a cough, feathers become ruffled. The second option, in which the respiratory and digestive organs are affected, ends in death.

How does bird flu manifest itself in humans? Symptoms in people at the initial stage are similar to those of a common cold or flu, but very quickly turn into pneumonia. Often the disease ends in death.

The incubation period is from one to seven days. The disease has an acute onset - with high fever, pain in the muscles and joints. The temperature (about 38 ° C) lasts 10-12 days, in severe cases it persists until death.
Laryngitis, rhinitis, bronchitis appear on the 2-3 day, there is a severe sore throat. Along with such symptoms, viral pneumonia develops with a disease such as bird flu.

Symptoms in humans can be not only intoxication and catarrhal. Very often, the gastrointestinal tract is also affected, which is accompanied by vomiting, diarrhea, and abdominal pain. There may be bleeding from the nose or gums. A person who has avian influenza becomes very ill very quickly.

Diagnostics

Professional medical assistance is needed at the slightest suspicion of bird flu. Symptoms in humans that occur after contact with a sick bird or person are a reason for immediate medical attention. The doctor-therapist will examine and interview the patient, as well as prescribe additional studies. When listening to the lungs, if pneumonia began to develop, hard breathing is determined, there are moist rales. X-ray examination reveals a rapidly spreading infiltration.

In a general blood test with such a disease, a decrease in the number of leukocytes, lymphocytes and platelets is observed. To make an accurate diagnosis, in addition to a blood test, it is necessary to take a swab from the nose.

A sick person may have an enlarged liver, possibly developing kidney failure.

How to treat?

Treatment of avian influenza takes place in the infectious diseases department of the hospital, where a person will then be prescribed symptomatic therapy. The most commonly used antiviral agent is Tamiflu, which was effectively used during the epidemics of 2008 and 2009.

A less weak but effective bird flu is Arbidol, which is prescribed in an increased dosage, which ensures the maximum antiviral effect. Medicines containing paracetamol (Ibuprofen, Nise, Efferalgan) help to cope with fever and fever. Preparations that contain interferon, necessary for the patient.

Equally important is the complete isolation of the patient, which prevents infection of other people. A sick person should have individual personal hygiene products, bedding, clothes, dishes, etc. In the acute period of the disease, it is often necessary to flush the upper respiratory tract to get rid of accumulated mucus. In addition, the patient must adhere to a strict diet, eliminating or limiting fried, spicy and sour foods.

Prevention

In order to avoid infection, you must:

• Avoid contact with wild birds.
• Children should be prohibited from hand-feeding them.
• At the slightest sign of illness in poultry, they must be destroyed by reporting the incident to the veterinary clinic.
• If you find a dead poultry, you must immediately bury it, wearing a tight mask, protective clothing and gloves.
• If you have pets, be sure to wash your hands regularly.
• It is necessary to undergo a course of preventive procedures in a medical institution, going to the territory where bird flu was detected. Prevention includes vaccinations and antiviral medications.
• Although cases of infection after eating chicken meat have not been officially registered, it is necessary to remember the precautions when preparing dishes from poultry meat and eggs. Careful heat treatment helps to destroy the virus.

If you have found even the slightest signs of bird flu, contact your doctor as soon as possible. Timely and qualified medical care will preserve your health, and in severe cases, even life.

10 questions and answers to the most popular questions about the flu epidemic at the Laishevsky poultry complex

At the Laishevsky poultry complex, the entire population of chickens will be destroyed - this is 450 thousand pieces. The All-Russian Scientific Research Institute of Animal Husbandry in Vladimir confirmed the assumption of Tatarstan veterinarians about an epidemic of bird flu at a poultry farm. Experts have discovered a highly pathogenic H5 virus in birds. The plant produced products under the brand name "Derevenka", about a million eggs managed to get on sale. What to do with "influenza" eggs, is it possible to get bird flu and will prices for chicken meat skyrocket - Realnoe Vremya answered the most popular questions.

Infected eggs got into kindergartens?! This is true?

Yes its true. The Laishevsky poultry complex supplied products to kindergartens and schools in Tatarstan. Since May 1, he has shipped 214,000 eggs to children's institutions. Theoretically, products can be contaminated with avian influenza, but to establish this for sure, you need to conduct laboratory tests. If they establish the presence of bird flu, then all products will be destroyed. Just in case, all batches of dubious eggs were sealed, they are not cooked from them.

I bought Derevenka eggs, will I get my money back if I return them to the store?

The store is unlikely to accept these eggs from the buyer. In order to return the product, you must prove that it is of poor quality. At a minimum, establish that these eggs are infected with the influenza virus. This is done in the laboratory of Rosselkhoznadzor. Whether the time spent is worth the cost of a dozen eggs is up to you.

Of the million eggs released from the factory since May 1, 300,000 have been located, plus the 214,000 that ended up in kindergartens. Photo ko-ko.ru

I ate the Derevenka eggs. Will I get bird flu?

You are not the only one in this situation. Of the million eggs released from the factory since May 1, 300,000 have been located, plus the 214,000 that ended up in kindergartens. All the rest were sold out and probably used. There are no known cases of influenza in the past few days as a result of this. The virus dies at a temperature of +70 degrees, and if you did not eat them raw, then nothing bad can even theoretically happen to you.

What should I do if I have infected eggs in my refrigerator?

See the answer to the previous question: the virus dies at a temperature of +70 degrees. Boil them hard-boiled and eat them boldly. The main thing is to wash your hands thoroughly, after contact with the egg - the virus may be on the shell. If you turn back at the mere thought that there are "flu" eggs in the house, then dispose of them. But just not throwing it in the trash in its raw form - they can become prey for pigeons and crows. For them, the virus is terrible - mass infection and death of wild birds will begin. The Rosselkhoznadzor advises: before throwing away, the eggs must first be boiled or, in extreme cases, buried.

But what about semi-finished products? They don’t write at all what poultry farm they come from?

The same. You don't eat them raw do you? Well, in general, Laishevsky specialized only in eggs, they did not produce chicken meat, so there can be no infection on display cases with wings and chicken legs.

Treatment is appropriate - plenty of fluids, antipyretic, antiviral drugs. Photo proalergico.sk

So bird flu is not dangerous to humans at all?

Not certainly in that way. It is not dangerous for those who eat properly and thoroughly thermally processed products. But it can be dangerous for poultry workers - people who come into contact with a sick bird. Symptoms of the disease are the same as with regular flu - high fever, sore throat, weakness. Treatment is appropriate - plenty of fluids, antipyretic, antiviral drugs. Such cases were - from 2004 to 2006, 167 people fell ill with avian influenza A virus in six countries - Vietnam, Thailand, Cambodia, Indonesia, China, Turkey, including 78 with a fatal outcome. Bird flu can be transmitted from person to person only when the virus mutates.

What will happen to sick laying hens?

All chickens from the infected poultry farm will be destroyed. This is about 450 thousand heads. The first 15,000 whose disease can be recognized without tests (the symptoms are the same as in humans - fever, weakness, snot) have already been burned. The rest, healthy or not, the same fate awaits in the near future. This is done for prevention purposes, so as not to cause mass infection of all birds in the region.

Pity the bird. Will they be burned alive?

Since the virus dies at high temperatures, it was decided to burn all the birds. As told in the Rosselkhoznadzor for Tatarstan, they will not destroy chickens with such a savage method as burning alive. The birds are first killed, there are several options - with the help of special preparations, gas chambers, or simply turning off the ventilation in the chicken coop. Only after that the carcasses will be burned.

Private farmsteads under the special supervision of veterinarians. Checkpoints have been set up around the focus of the infection and operate around the clock. Photo ko-ko.ru

What should the owners of private farmsteads that contain chickens do?

Quarantine has been introduced in the Laishevsky district. The area around the village of Sovkhoz im. On October 25, where the Laishevskaya poultry farm is located, it was divided into two zones, in the threatened zone of infection within 5 km there are three settlements - the village of Aleksandrovsky, the village of Srednee Devyatovo, the village of Smoldeyarovo. Private farmsteads under the special supervision of veterinarians. Checkpoints have been set up around the focus of the infection and operate around the clock. The second zone - within a radius of 10 km - belongs to the surveillance zone, it includes the city of Laishevo, the villages of Imenkovo, Chirpy, Yemelyanovo and several villages. Residents who keep a bird need to carefully monitor its health.

Are eggs going up in price?

The factory, although it was one of the largest in Tatarstan, but, as stated in the Ministry of Agriculture of the republic, occupied only 10% of the egg market of the republic. As Minister of Agriculture Marat Akhmetov said, "there may or may not be a slight increase in prices." We are talking about eggs, the factory did not produce meat, and the flu epidemic at Laishevsky should not affect its prices. As for the damage to the enterprise, it is about 100 million rubles. After the quarantine is lifted and the factory is disinfected, after three months, the owners can restore work. The Ministry of Agriculture promised to help.

Daria Turtseva