How African swine fever spreads and how to fight it. African swine fever: everything you need to know about the dangerous disease Swine fever

The disease is characterized by high mortality, clinical signs and pathological changes similar to the acute form of classical swine fever.

Etiology

African swine fever (ASF) is a very dangerous contagious infectious disease of pigs. The causative agent is African swine fever virus (ASFV), which is the only representative of the Asfivirus genus of the Asfaviridae family. The ASF virus is not related to the classical swine fever virus, from which it differs in antigenic composition and immunological properties. The resistance of the ASF virus to temperature, chemical factors and other environmental conditions is high. The virus was detected in the chilled meat of sick pigs after 5 months, in the bone marrow - 6 months; in blood stored at room temperature, the pathogen remained infectious for 10-18 weeks, in feces for 11 days. According to other authors, the virus remained infectious at a temperature of 5°C for 6 years, and at room temperature for 18 months. From the data presented it follows that at low temperatures it remains viable and virulent for several years; heat destroys it quickly: at a temperature of 55°C the virus dies within 45 minutes, and at a temperature of 60°C within 20 minutes.

A 2.0% solution of caustic soda has a more powerful effect on the virus (1.0 l of solution per 1.0 m2 of box surface kills the virus in dry blood within 24 hours), a 1.0% solution under the same conditions does not destroy virus. Virkon S (1:100) is now recommended as a disinfectant in the fight against ASF. The virus retains its properties under unfavorable environmental conditions (drying and rotting). In Spain, the ASF virus was discovered in pens where animals were killed 4 months ago. In blood kept in a cold and dark room, it remained viable for 6 years, in remains rotting at room temperature for 1-18 weeks, and in a spleen buried in the ground for 280 days.

Spreading

African swine fever is observed in Africa and periodically in South America. In Europe, it is currently only found in Sardinia. In 2007, outbreaks of ASF were registered in Georgia. In Poland, no cases of this disease had ever been detected in pigs before. The main source of the domestic pig epizootic is wild African pigs, which are asymptomatic carriers and carriers of the virus, as well as sick and recovering domestic pigs. Other types of domestic animals are not susceptible to the ASF virus. Pigs vaccinated against classical swine fever are not protected against African swine fever.

Poland does not belong to the highest ASF threat zone. However, due to increasing direct ties and exchange of goods with countries affected by the disease, there is a threat of its introduction.

In the modern course of the disease, two cycles of infections can be distinguished:

1. an old cycle in which the virus circulates mainly between African wild pigs, and infection of domestic pigs is the result of accidental infections;

2. a new cycle in which the epizootic exists and spreads exclusively among domestic pigs.

In infected pigs, the virus is present in all body fluids, excretions and secretions. The release of the virus into the environment begins 7-10 days after the increase in body temperature. The largest amount of the virus enters the environment with feces, as well as by aerosol from the respiratory system. Transmission of the virus from sick pigs to healthy animals

It can occur through direct contact, or indirectly through contaminated food, water, other objects, as well as through insects. The most important source of infection is meat, meat products, raw kitchen waste and waste from the slaughter of sick pigs or virus carriers. With direct contact, infection occurs quickly. Due to the presence of recovering animals and asymptomatic carriers, the disease spreads quickly in the herd.

Pathogenesis

After entering the body, the virus enters through the lymphatic and blood vessels into cells and tissues with which it has a special affinity

(tonsils, lymph nodes, kidneys, spleen). It's intense there

multiplies and returns again to the circulatory system, where it remains until the death of the animal. This phenomenon is accompanied by an increase in body temperature and other general symptoms of the disease. Clinical signs and exacerbation of the disease depend on which organs were damaged.

Clinical signs

The incubation period averages 4-9 days, but can be shorter or longer, depending on the degree of virulence of the pathogen. The longest incubation period of the disease is 21 days. The first clinical sign of the disease is an increase in body temperature to 41-42°C, which, unlike classical swine fever, is not accompanied by other symptoms. Pigs with a high body temperature retain their appetite, move normally and only a few show signs of restlessness or lie down a lot. Animals remain in this state for 2-3 days, i.e. until the body temperature drops.

Then other clinical symptoms appear, which quickly intensify and lead to the death of the animal within a few, rarely several tens of days.

The most common clinical symptoms that appear after

Presence of blood in the bladder

decrease in temperature and precede the death of sick animals include: blue discoloration of the skin of the ears, abdomen and sides of the body, minor hemorrhages on the skin, suffocation, discharge in the form of foam from the nose, discharge from the conjunctival sac, diarrhea (often mixed with blood), vomiting and paresis of the posterior parts of the body. Nervous signs such as restlessness, muscle convulsions and clonic-tonic seizures were observed in some experimentally infected pigs. Pregnant sows tend to have abortions. Hemorrhages are often found on the membranes and skin of the fetus.

The disease occurs, as a rule, in an acute form, or less often in a hyperacute form, when animals die suddenly or after a short period of time. In countries where the disease has been observed for several years (African countries, Spain, Portugal, the number of cases of the chronic form of the disease increases. In the chronic form, the disease lasts 20-40 days and ends in death, sometimes recovery. Sick pigs are emaciated, which is not detected when acute course of the disease.Observe, alternately, improvement and deterioration of health, signs of inflammation of the lungs and pleurisy, joints and tendon sacs, periodic diarrhea and isolated foci of skin necrosis.

The mortality rate for African swine fever (depending on the degree of virulence of the pathogen and the form of the disease) is 80-100% of sick animals.

Pathological changes

Due to the rapid progression of the disease, the corpses of pigs killed by ASF do not look emaciated, except in chronic cases, but, on the contrary, appear swollen. Hardening and putrefactive decomposition of tissues after death occurs quickly, so an autopsy should be performed soon after the death of the animal.

Numerous hemorrhages under the serosa of the intestine

The skin is locally colored blue-red (cyanosis) and dotted with small hemorrhages. Traces of discharge are visible around the natural openings of the head, and traces of diarrhea are visible near the anus.

In the body cavities, a large accumulation of yellow-pink exudate is found as a result of the admixture of blood and fibrin, small and large hemorrhages under the serous membrane covering various organs - especially the small intestine. In addition, severe hyperemia of the mucous membrane of the colon and serous infiltrate in the lumbar, inguinal and gastrohepatic regions, swelling and infiltration of the interlobar tissue in the liver, as well as hemorrhages in the cardiac membrane are striking.

The most characteristic changes are observed in the spleen, lymph nodes, kidneys and heart. The spleen undergoes two- to four-fold enlargement and severe hyperemia in more than 70% of sick pigs, acquiring a dark blue or black color. The organ tissues on the cut are softened, filled with blood, almost black in color, there are no protruding lymphatic tubercles. Sometimes the described changes affect only part of the organs; the remaining spleen tissue may have small, outlined bleeding foci (collapses).

Lymph nodes are enlarged, have hemorrhages or tissue necrosis. Usually the lymph nodes of the stomach, liver and mesentery are most affected. All of them are significantly enlarged, dark red or black in cross section, of an erased structure, more like a blood clot.

In the kidneys, hyperemia of the cortex, single or numerous hemorrhages or blood filling of the renal sacs and pelvis are noted.

In the heart, hemorrhages and bruises in the myocardium or endocardium are found in 50% of sick pigs.

In the digestive tract, hemorrhagic inflammation of the gastric mucosa with ulcerative and necrotic lesions, blood clots in the esophagus are observed. On the mucous membrane of the small intestine there is acute catarrhal or hemorrhagic inflammation with numerous hemorrhages under the serous membrane; in the large intestine - severe bleeding and inflammation of the mucous membrane of the cecum and colon with numerous hemorrhages, hyperemia and swelling of the submucosal layer, as well as hemorrhages in the accessory lymph nodes. In acute and subacute forms of ASF, buds are not observed in the intestines, although they can be detected in the chronic course of the disease.

Differentiating African swine fever from classical swine fever based on clinical signs is a difficult problem. Reasons to suspect ASF arises if the disease occurs in an acute form. At the same time, it spreads quickly and is characterized by almost 100% mortality in different age groups of pigs. Suspicion becomes more justified if the disease appears in animals from farms located near large centers or important communication lines.

Selection and forwarding of material for research. Laboratory diagnostics.

Laboratory studies and biological tests to confirm or exclude ASF are carried out exclusively at the State Veterinary Institute (Pulawy). The most suitable samples for virus isolation and antigen detection are the spleen, tonsils, and whole blood (taken from EDTA- or heparin-stabilized samples). Tissues from other organs can also be used for laboratory studies: lungs, lymph nodes, kidneys and bone marrow.

For research, a fragment of the spleen weighing 40.0 g should be sterilely selected from at least two dead or forcedly killed pigs suspected of ASF with an acute form of the disease. Transfer of spleen fragments from a larger number of pigs is recommended when there is a chance of isolating the virus and recognizing the disease. The organs must be in good condition and must be delivered to the laboratory within a short period of time. To do this, after selection, each tissue must be placed in a separate plastic bag and then in a thermos with ice. Biological material intended for research must be refrigerated, but not frozen. Laboratory research involves isolating the virus or detecting its genetic material using PCR technology.

A letter must be attached to the submitted material, which should indicate the epidemiological, clinical and pathological results of the research.

Blood samples for serological enzyme immunoassay (ELISA) immunoblotting should be taken from pigs that have been ill for as long as possible or from pigs that have been in contact with infected animals, as well as those suspected of being infected with the ASF virus.

Control measures

The district veterinarian working within the Veterinary Inspectorate is responsible for the fight against African swine fever. He acts on behalf of the Chief Veterinarian and may authorize veterinarians to carry out activities on his behalf. The principles of combating ASF are regulated by the relevant instructions. A vaccine against ASF has not yet been developed.

African swine fever (ASF) is primarily spread to South Africa, hence the name of the disease. Another name is Montgomery disease. The first identified disease of the 20th century. The virus was gradually transferred to Portugal, Spain and various countries in the Americas. Towards the end of the century, the active spread of the disease among wild animals began. The infection then spread to domestic stock.

ASF is an infectious disease of the excitation type. It provokes the occurrence of fever, various inflammatory processes, necrosis and diathesis and other manifestations.

The disease is fatal; there are not many domestic animals that produce antibodies and survive the disease. Deceased pigs have some characteristic features in the structure and pathological changes of organs:

1. Connective tissues are affected and have many sources of hemorrhage;
2. Some organs increase in size - the liver gland, spleen and kidneys;
3. Lymphs in the body in appearance consist of multiple blood clots;
4. The lumen in the stomach and respiratory system contains serous-hemorrhagic fluid, it also contains fibrin and blood particles;
5. Severe swelling in the lungs.

The symptoms of the disease are similar to standard fever, but the causative agent is completely different. The virus that causes inflammation is Asfivirus, which belongs to the Asfarviridae family. Today, the virus has already mutated somewhat and seroimmune genotypes of ASF are isolated.

The ASF genome is extremely resistant to all types of influences, is not destroyed by acid pH from 2 to 13. It survives a large number of temperature changes. Tends to retain the ability to reproduce even when drying out, crystallizing due to low temperature and rotting. The virus survives even when meat is stored in the freezer for a long time or the flesh rots. The only available way to destroy bacteria is heat treatment at high temperatures.

It has been observed that African breeders suffer less from the disease. There are much more pigs that survived the plague epidemic than in Eurasian latitudes.

Infection methods

ASF disease is often transmitted through mucous membranes: conjunctiva, oral cavity. Even direct contact with an animal can cause infection; the virus penetrates the skin.

Various animals and even people can be carriers of the virus. So birds, small rodents that feed on leftover food from pigs are the main carriers of the disease. People who have eaten meat or come into contact with pigs can carry the virus on their skin or in their bodies. Infected pigs themselves are also carriers of the disease.

Consequences of ASF - death

Pathogen bacteria can persist in waste and feed for a long time. One infected individual can make an entire pasture unusable, since the virus is extremely aggressive and spreads extremely quickly.

There is no relationship between age, gender, breed or other indicators on the risk of infection. All animals are susceptible to ASF. There are cases when it is necessary to destroy entire plants with a population of 60 thousand individuals due to the development of infection.

Symptoms

The period from infection to the first symptoms is 5-15 days. Quite often, manifestations begin only after 2 or more weeks; here the number of viral bacteria plays a decisive role; the more foci, the faster the disease develops. Also, the general health of the pig somewhat restrains the disease until the period of first manifestation.

The disease can have different forms, so they are distinguished:

1. Acute - the animal is quickly affected by symptoms and it dies soon. At the same time, the pig’s temperature rises to 40.5 – 42°C, a lethargic, weak state, and clearly noticeable shortness of breath. Foci of purulent effects on the mucous membranes of the nose and conjunctiva, paresis is observed in the hind limbs. Stomach upset in the form of constipation, vomiting, diarrhea with particles of blood clots. The skin has bloody discharge, often appearing on the ears, neck, especially the lower part, on the stomach and perineum. Usually accompanied by pneumonia. Disease progression over 1 day to 1 week. The final stage of the disease is a decrease in body temperature, then the animal falls into a coma, then death;
2. Hyperacute - the individual almost certainly dies in a short time. The fatal outcome is immediate, even symptoms do not have time to appear;
3. Subacute - gradual spread of foci of the disease, manifestations are similar to the acute form, but to a lesser extent. The pig experiences fits of fever, lack of appetite and general loss of strength. Death occurs within 2-3 weeks, the cause of death is heart failure;
4. Chronic form - the animal has constant signs of ASF, but with moderate symptoms. Often occurs against the background of infections of bacterial origin. Breathing becomes difficult, the animal has a fever, and the wounds do not heal. Physical exhaustion sets in and the individual lags behind in development. In this case, the synovial membranes and tendons have pathological abnormalities in the structure.

It is worth noting that regardless of the type of disease and the viability of the individual, it should be destroyed in order to avoid the spread of the virus to the livestock in the region.

Diagnosis of African plague

The first characteristic feature of ASF is the appearance of cyanotic spots, sometimes blood stains are visible on the skin. Any of these symptoms should be examined by a veterinarian. Suspicious animals should be immediately separated from the rest of the herd to determine the type of virus. It is worth isolating not only him, but also the food he consumes, the water. There should be nothing in common with other animals.

Then it is necessary to examine the remaining individuals. A conclusion about the state of health cannot be made during the incubation period and before the examination process. Pathological changes in the structure of organs and the clinical picture make it possible to determine the source of the appearance of spots or other diseases. Alas, the entire herd will have to be destroyed, since this is a risk for the entire region of residence, otherwise the infection through insects will spread into an epidemic.

The next stage of diagnosis is to determine the type of infection, the source of the African swine fever infection.

To determine the pathogen, it is necessary to conduct biological tests and laboratory studies. This way, during the examination, not only the virus, but also the antigen is detected. Antibody testing becomes the final factor in determining the disease. It is likely that this is not ASF, but ordinary plague; the variety can be identified on the basis of differential diagnosis.

Virus treatment, quarantine

The virus has a high level of aggression towards pigs and spreads extremely quickly, so it is forbidden to expect recovery. At the same time, today there is simply no vaccine against ASF, despite some loud assurances - it’s a fairy tale. The only way out until today is the complete destruction of infected individuals and everything associated with them.

The video talks about the history of the virus, the main dangers and why it has become so widespread.

Video - African swine fever

Scientists are constantly searching for a vaccine for the virus, but as soon as they get close to discovery, the virus mutates. Constant changes in the structure make it impossible to determine its vulnerability and implement treatment. Since the emergence of the plague and about 10-20 years ago, all cases of infection have been fatal. Today, the disease is increasingly becoming chronic and asymptomatic, so you shouldn’t count on visible symptoms.

The main opportunity to preserve livestock is a thorough examination of animals. Constant, regular procedures allow you to notice the disease in a timely manner if symptoms exist. Otherwise, only examinations can show the virus. So, if you keep animals in different cages and minimize contact between individuals, you can avoid mass infection, but that’s only if you’re lucky. Since the virus spreads extremely quickly and easily, preventing its spread is quite difficult.

All individuals are quarantined and various tests are carried out. If it is possible to determine that they are infected with ASF, the animals are destroyed.

Measures after detection of the virus

Today, effective measures to prevent the spread of the ASF virus within livestock simply do not exist. It is necessary to adhere to the best recommendations, by current standards, namely: to contain further spread, minimize the risk of infection of other animals, suppress outbreaks of plague before the outbreak of an epidemic.

If an outbreak of ASF is detected, all livestock must be destroyed. In this case, the blood is first removed. Together with the corpses, household items with which the pigs come into contact and contaminated food are burned. The remaining ash should be mixed with quicklime and buried. All adjacent areas of the ASF outbreak are treated with a hot solution of sodium (3%) and formaldehyde (2%).

Animals close to the outbreak site are at risk, so they are slaughtered. The meat is suitable for consumption, but after heat treatment, it is canned. The clearing area is 10 km. A quarantine is declared throughout the region. It lasts about 6 months from the moment of the last outbreak and death of pigs. The area for pasturing and keeping livestock is unsuitable for use for 1 year after the quarantine is lifted, and requires inspection by the relevant authorities.

Prevention does not allow us to talk about complete protection against the spread of the virus, but it is still possible and significant to minimize the risk. Maintaining hygiene is the key to the health of pigs, not only from the African swine fever virus, but also from various others.

How does ASF threaten people?

Most medical and health epidemic stations agree that this type of plague is harmless to humans. People do not succumb to the disease, especially since the virus dies at a temperature of 70°C. Cooked meat, even if it has been contaminated, will not have negative consequences for humans.

There is also the factor that the virus is constantly in the stage of mutation, so it is quite difficult to predict the further development of the situation. It is reported that a person is not able to become infected with the virus, since there has not been a single clinical case.

The main damage to people from the African plague is of an economic nature. Humanity is experiencing great costs in destroying huge numbers of pigs and implementing sanitary measures. Over the past 10 years alone, 500 outbreaks of plague have been documented within Russia. The total number of livestock destroyed today is more than 1 million. In economic terms, losses amount to 30 billion rubles. Around the world, one can only guess at the scale of the disease and losses.

Research into the danger of the virus to humans

Not all scientists are so optimistic; various studies have been conducted that have alarming conclusions about the effects on humans. Despite the absence of disease in humans from the virus, there are documented responses to the production of antibodies against it. This indicates entry and an attempt to infect the body.

Scientists have conducted research and report the discovery of new sequences of viral origin in human blood. They are directly related to aspharoviruses (the only representative of the ASF group). This indicates greater genetic diversity of the virus than previously known.

It is also noted that no one has conducted massive research to search for the ASF virus in people, since there are simply no symptoms. Despite the absence of obvious symptoms, this does not indicate complete health of the person and the absence of the possibility of infection. The main effect of bacteria is immune in nature; it is this system that is destroyed in pigs when they are sick.

Tropical countries, the main source of the virus, are facing many fevers today. In 40% of cases, it is not possible to find the causative agent of fever, in particular dengue. In Nicaragua, a study was conducted on 123 patients for whom the etiological component of the virus could not be established. Thus, it was possible to determine the source of the disease in 37% of these patients; 6 of them had various viral pathogens, including ASF.

This indicates that the latest diagnostic technique allows us to determine the etiology of the ASF disease. The most important thing is that the risk of ASF still exists, but it is quite difficult to determine. The plague can infect a person and even lead to death, but these are only isolated cases.

In general, the virus is safe for humans, but it mutates quickly. Also alarming results from tropical studies (others have been conducted) indicate the risk of disease for humans. In general, the ASF virus, despite its long history, is still poorly understood and the search for an effective remedy lies ahead.

Conclusion

Video - conclusion at the end of quarantine

ASF is considered a safe virus for humans. Even when purchasing infected meat, no one eats it raw; cooking at a temperature of 70°C or higher destroys the pathogen. Neglecting safety measures and selling contaminated meat is strictly prohibited, as this can provoke an epidemic in pigs throughout the world. The high adaptive ability of the virus has been noticed for a long time, so further development of the disease must be stopped and localized at its inception.

Since ancient times, outbreaks of various epidemics have wiped out entire cities from the face of the earth. Often, not only people, but also animals and insects become victims of diseases. There is nothing more deplorable for livestock farmers than merciless extinction.

One of these terrible diseases is African swine fever, which is not dangerous to humans, but it is very important to know the symptoms and be able to diagnose and prevent the disease.

What is African swine fever

African swine fever, also known as African fever or Montgomery disease, is an infectious disease characterized by fever, inflammation and loss of blood supply to internal organs, pulmonary edema, skin and internal hemorrhages.

African fever is similar in its symptoms to classical fever, but has a different origin - a DNA-containing virus of the genus Asfivirus of the Asfarviridae family. Two antigenic types of virus A and B and one subgroup of virus C have been identified.

ASF is resistant to an alkaline environment and formaldehyde, but is sensitive to an acidic environment (therefore, disinfection is usually carried out with chlorine-containing agents or acids), and remains active at any temperature.

Important! Pork products that have not been subjected to heat treatment retain viral activity for several months.

Where did the ASF virus come from?

The first outbreak of this disease was recorded in 1903 in South Africa. Plague spread among wild pigs as a persistent infection, and when a outbreak of virus infection occurred in domestic animals, the infection acquired an acute form with a 100% fatal outcome.

After some time, an outbreak of infection was registered in Spain, bordering Portugal. For more than thirty years, these states took measures to eliminate ASF, but it was only in 1995 that they were declared free of the infection. Four years later, an outbreak of the deadly disease was again diagnosed in Portugal.

Further, symptoms of African swine fever have been reported in pigs in France, Cuba, Brazil, Belgium and Holland. Due to an outbreak in Haiti, Malta and the Dominican Republic, all animals had to be killed.
The disease was first discovered in Italy in 1967. Another outbreak of the plague virus was identified there in 1978 and has not yet been eliminated.

Since 2007, the ASF virus has been spreading in the territories of the Chechen Republic, North and South Ossetia, Ingushetia, Ukraine, Georgia, Abkhazia, Armenia and Russia.

African plague causes colossal economic damage associated with the forced slaughter of all pigs in outbreak areas, quarantine and veterinary and sanitary measures. Spain, for example, suffered losses of $92 million due to the eradication of the virus.

How does ASF infection occur: causes of infection with the virus

The genome affects all wild and domestic animals, regardless of age, breed and quality of their care.

How is African swine fever transmitted?

Symptoms and course of the disease

The incubation period of the disease is approximately two weeks. But the virus can manifest itself much later, depending on the condition of the pig and the amount of genome that has entered its body.

Did you know? The structure of the gastrointestinal tract of pigs and their blood composition are close to those of humans. Animal stomach juice is used to make insulin. Donor material from piglets is widely used in transplantology. And human breast milk has a composition of amino acids similar to pork.

There are four forms of the disease: hyperacute, acute, subacute and chronic.

External clinical indicators of an animal with a hyperacute form of the disease are absent, death occurs suddenly.

In the acute form of African swine fever, the following [signs of the disease] appear:

• body temperature up to 42 °C;
• weakness and depressed state of the animal;
• purulent discharge from the mucous membranes of the eyes and nose;
• paralysis of the hind limbs;
• severe shortness of breath;
• vomit;
• difficult stool ejection or, conversely, bloody diarrhea;
• skin hemorrhages in the ears, lower abdomen and neck;
• pneumonia;
• motor impairment;
• premature abortion of inseminated sows.

• attacks of fever;
• state of depressed consciousness.

The chronic form is characterized by:

• attacks of fever;
• non-healing damage to the skin;
• difficulty breathing;
• exhaustion;
• developmental delay;
• tenosynovitis;
• arthritis.

Diagnosis of African plague

The ASF virus appears as purple-blue spots on the skin of animals. If such symptoms are present, it is important to identify the symptoms as soon as possible and isolate the animals.

To accurately diagnose the virus, a comprehensive examination of infected livestock is carried out. After clinical studies, a conclusion is made about the cause and route of infection of infected pigs.

Bioassays and studies carried out in the laboratory make it possible to determine the genome and its antigen. The decisive factor for identifying the disease is an antibody test.

Important! Blood for serological study of enzyme immunoassay is taken both from long-term sick pigs and from individuals in contact with them.

To conduct laboratory tests, a blood sample is taken from infected livestock, and organ fragments are taken from dead bodies. The biomaterial is delivered as quickly as possible, in individual packaging placed in a container with ice.

Control measures when African swine fever is detected

Treatment of animals with a highly contagious infection is prohibited. A vaccine against the ASF virus has not yet been found, and the disease cannot be treated due to constant mutation. If previously 100% of infected pigs died, today the disease is increasingly chronic and occurs without symptoms.

Important! If a focus of African plague is discovered, it is necessary to subject the entire livestock to bloodless destruction.

The slaughter area must be isolated, the corpses must subsequently be burned, and the ashes mixed with lime and buried. Unfortunately, only such strict measures will help prevent the further spread of the virus.

Contaminated food and animal care items are also burned. The territory of the pig farm is treated with a hot solution of sodium hydroxide (3%) and formaldehyde (2%).
Cattle at a distance of 10 km from the outbreak of the virus are also slaughtered. A quarantine is declared, which is lifted after six months if there are no symptoms of African swine fever.

The territory infected with ASF is prohibited from being used for pig farming for a year after the quarantine is lifted.

Did you know? The largest farrowing in the world was recorded in 1961 in Denmark, when one pig gave birth to 34 piglets at once.

What to do to prevent ASF disease

To prevent infection of a farm with African swine fever, it is necessary carry out disease prevention.

African swine fever has increasingly begun to affect livestock in Russia. Cattle breeding farms in the Leningrad, Nizhny Novgorod, Saratov, Tver, Omsk regions, Sosnovsky district and other large settlements are concerned about how to maintain their livestock numbers. Every farmer should know the symptoms of swine ASF and how it is transmitted. Many people are concerned about the question of whether this infection is transmitted and what danger it poses to people. And also is it allowed to eat meat from infected pigs?

African swine fever - what is this disease?

Porcine ASF is a viral disease that is quite resistant to treatment. Experts believe that the infectious agent remains viable for 18 months. Individuals of all ages can get sick. Scientists distinguish several subtypes of infection: A, B and C. This disease was first discovered on the African continent, hence its name. In the natural environment, the virus is transmitted by wild African pigs and insects of the genus Ornithodoros.

The disease affects individuals of all ages

How is African swine fever transmitted?

Livestock can become infected with African swine fever after contact with infected animals. Also, the causative agent of the disease can be in feed, water, equipment, and vehicles for transporting pigs. Damage to the mucous membranes and skin, blood and insect bites help the virus penetrate.

Sick animals often die. Individuals that were able to survive become carriers of the infection. Once in the blood, the virus multiplies quickly. After the first symptoms appear, the disease affects more than 37% of the herd.

Note! All livestock located 10 km from the source of the outbreak are at risk of infection.

Is African swine fever dangerous for humans?

Scientists are confident that ASF is not dangerous to humans - the human body is not susceptible to the pathogen. There will be no harm to health even when a person eats the meat of an infected animal. To date, not a single case of transmission of this disease to people has been recorded.

Despite the fact that ASF, according to scientific data, is not dangerous to humans, experts believe that there are still some risks.

Attention! Meat from infected individuals is allowed to be consumed only after undergoing long-term heat treatment. Smoking products does not kill the plague pathogen.

Reasons why you should avoid eating such meat:

• The infection can weaken a person's immune system.
• The disease develops unexpectedly. The virus is classified as an asphavirus and has the ability to mutate. There is a high probability of its modification and the emergence of new variations.
• ASF can aggravate the development of serious diseases.

Symptoms of African swine fever

The incubation period lasts from 2 to 14 days. The duration of the period is influenced by: how much virus has entered the body, the individuality of immunity and the form of the disease. Timely diagnosis at the initial stage plays an important role in treatment. The disease has several degrees, differing in the first manifestations:

• fever (temperature above 40°C);
• loss of appetite;
• apathy;
• difficulty breathing, cough;
• the appearance of discharge from the eyes and nose;
• motor impairment, instability;
• paralysis of the hind limbs;
• pneumonia;
• the appearance of bruises, subcutaneous swelling on the face and torso;
• hair loss;
• failure of the gastrointestinal tract;
• vomit.

Pig sick with African fever

Important! The peculiarity of the virus is that the symptoms may not fully manifest themselves. The disease can be lightning fast, in which case the individual dies without showing symptoms.

Description of the forms of the disease

There are two forms of ASF: chronic and atypical

• Chronic form can last up to 60 days. Individuals suffer from diarrhea, fever, loss of appetite, cough and shortness of breath. Pigs lose weight, their skin wrinkles and bruises appear on the inside of the thighs, belly and face.
• Atypical form most often affects piglets whose maternal immunity has already been formed. With this form, animals can recover, but the likelihood of complications is high. According to the latest data, the mortality rate is 30-60%.

Diagnosis of ASF

It is impossible to diagnose “African plague” at home. Laboratory tests are required for detection. Diagnosis is also accompanied by the collection of samples, specimens and pathological and epizootological data. The best diagnostic methods are the fluorescent antibody method and the hemadsorption reaction.

Sampling

Treatment of African swine fever

To date, a cure for the causative agent of the disease has not yet been created. You can get rid of ASF by exterminating the entire herd located in the quarantine zone. It is recommended to destroy animals in a bloodless manner and burn the carcasses. It is also worth paying special attention to the place where the herd is kept: all equipment and floor coverings are burned.

Prevention

The following preventive measures will help:

• buy food from certified sellers where there is no risk of contamination of the product with infections;
• before serving, heat treat animal feed;
• regularly treat the farm and equipment with disinfectants;
• minimize contact between pigs and birds;
• purchase animals that have received documents and been examined by a veterinarian;
• vaccinate sows.

Important! When the first signs of illness are detected, the animal must be isolated.

ASF is a viral disease transmitted through objects in contact with a sick individual. Although there is no cure for it, livestock can be protected through vaccination, disinfection and limiting contact between pets. The virus is not yet dangerous for humans, however, the possibility of its mutation cannot be ruled out.

The African swine fever virus, which appeared relatively recently, is dangerous due to its ability to spread rapidly. The disease poses a threat to animals, completely destroying livestock. Often, to prevent the spread of infection, it is necessary to get rid of both sick and healthy individuals, which is detrimental to the development of pig farming.

What is African swine fever

There are several known names for African swine fever. These include East African fever and Montgomery virus. In Latin, the infection is called Pestis Africana suum, and the abbreviation is ASF.

The African infection is dangerous for animals; in acute, severe cases of the disease, the outcome is always fatal.

The disease occurs due to a virus that multiplies in blood cells (in the cytoplasm). The infection affects the synthesis of proteins and DNA. Even if a pig has suffered ASF, it remains a source of danger for healthy individuals. This happens because the animal does not acquire immunity to this infection after illness. In addition, the virus is able to accumulate in the blood, entering the external environment; it does not die even under the influence of high temperatures, when the percentage of humidity or pH changes.

History of appearance

The infection originated on the African continent, hence the name of this disease. Initially, the infection affected wild boars. The animals' bodies gradually adapted to the virus, trying to fight it. As a result, the individuals acquired immunity to ASF, but remained carriers and spreaders of the African swine fever virus.

After European colonists arrived in Africa and brought livestock from their homeland, widespread infection began to occur. It turned out that the newly arrived animals were not immune to ASF.

At the beginning of the twentieth century, South Africa experienced a complete decline in livestock production. It was then that ASF was first described. At the same time, all the blame was placed on wild boars, which were carriers of the virus.

Despite the fact that the disease has already migrated to Europe, the African infection is still not fully understood.

Distribution routes

ASF arrived on the European continent in the first half of the 20th century. The first victims were Spanish and Portuguese pigs. After the end of World War II, African swine fever found its way into Latin America. By the end of the last century, the infection spread to Asia, then to Eastern European countries. In Russia, an outbreak of the African virus occurred in 2007. Then more than 1,000,000 pigs were destroyed.

Ways of spread of infection:

• The virus, which multiplies in the blood of animals, is transmitted through the bites of blood-sucking insects (mosquitoes and ticks).
• Infection occurs through contact between virus carriers and healthy livestock.
• Often the source of ASF is food, or more precisely the additives contained in its composition.
• Sick pigs releasing germs into the environment also contribute to the spread of the deadly disease.

Symptoms of African swine fever

The disease is quite difficult to recognize. Often a dangerous infection manifests itself in the same way as the classic plague. The clinical picture depends on the course of the disease.

The rarest and most dangerous form is the hyperacute course of the disease. It is characterized by the following symptoms:

• high (up to 42 ℃) body temperature;
• state of fever;
• general depression.

The disease develops very quickly. Therefore, this option is also called lightning fast. It ends with the death of the pet in 2–3 days.

The acute form of ASF also ends in death - on average after 5-9 days. General signs:

• the appearance of conjunctivitis;
• redness of the skin, especially in the area around the eyes;
• temperature increase (42 ℃);
• increased heart rate and breathing;
• bloody discharge from the nose (late stage).

The subacute form is characterized by the same symptoms. However, with this form the course of the disease is not so severe. It happens that the pig recovers, but remains a carrier of the infection.

The main signs of the disease in chronic course:

• the skin turns blue and swells;
• at times a febrile state appears;
• swelling may appear under the skin.

In the chronic form, the pig is sick for an average of 2 to 10 months. Often the animal dies due to inflammation or exhaustion.

In addition, there is a form of ASF that passes without visible symptoms. This species is more common in wild boars, but also affects domestic pigs. In this case, the individual is considered a source of threat to healthy fellows.

How does ASF threaten people?

Laboratory studies of African plague have shown that the virus, which is deadly for domestic animals, does not pose a danger to humans and does not threaten his health or life. Meat obtained from an individual who has recovered from ASF is safe and suitable for consumption. In this case, a prerequisite is heat treatment at high (from 80 ℃) temperature. Pigs and piglets that are at risk of infection are usually slaughtered for meat products.

Despite the safety of the disease for people, veterinarians continue to sound the alarm. After all, the African virus is constantly mutating and changing. Scientists believe that it is possible that a new, unknown type of ASF will emerge, which could pose a danger to human health and life.

Is there a treatment

The disease is life-threatening for animals. Signs of African swine fever are not clearly visible, making it difficult to make a diagnosis. In addition, it happens that an animal becomes infected with a fulminant form, which occurs in the shortest possible time and always ends in death.

African plague has not yet been fully studied. Accordingly, a suitable way to get rid of this scourge, which is harmful to the economy and the development of livestock farming, has not been determined. No effective drugs have been found to treat the deadly disease.

Even in the case of a favorable outcome, recovered pets remain a source of threat to the health of their fellow animals. A pig that has recovered from the disease remains a virus carrier forever.

Eliminate outbreaks and prevent spread

First of all, it is necessary to take into account the danger of infection. Another important factor is the lack of effective treatment. Considering these aspects, the way out of the situation becomes obvious.

If pigs show signs of African swine fever, the only way out is to destroy the livestock. Of course, this method of dealing with the problem that has arisen causes significant damage to the country’s economy and harms the development of agriculture. Moreover, both sick animals and uninfected animals kept on the same farm are destroyed. However, today this is the only possible way out.

Measures taken to combat infection are under the control of the veterinary service. All preventive measures are carried out in accordance with Rosselkhoznadzor standards.

Prevention

Despite the fact that the infection is incurable and threatens the life of the pig, the situation is not hopeless. It is necessary to know about preventive measures that will prevent infection of livestock and help avoid mass deaths of pets.

The main thing is to ensure that veterinary certificates are available when purchasing adult males or females and young piglets.

When farming and keeping pigs, it is recommended to observe a number of conditions:

• Ensure that livestock is raised in accordance with the rules established by the veterinary service.
• Do not pollute the environment with animal waste.
• Implement quarantine measures in a timely manner.
• Immediately isolate sick animals.
• Do not graze pigs in areas close to the infection zone.

Quarantine

One of the necessary measures to stop the spread of a deadly disease. Quarantine is carried out after identifying the source of infection that threatens the life of pigs.

Animals that are at risk of disease, as well as infected individuals, are destroyed using a bloodless method. Equipment, feed, partitions, dilapidated old premises, fences, and feeding troughs are also subject to liquidation. As a rule, everything is burned. If this is not possible, then the corpses of pigs, equipment, wooden floors, etc. are buried in the ground to a depth of at least 2 meters.

In a zone whose coverage is 5 km, all pets (both piglets and adults) are registered.

Forbidden:

• remove pigs from the quarantine zone;
• sell livestock and poultry of any kind;
• trade in meat, milk, etc.

Removing quarantine

When the number of sick and at risk of infection pigs has been destroyed, livestock care items have been eliminated, and measures are taken to disinfect the area. After this, it is necessary to obtain a veterinary control report confirming the cleanliness and safety of the place.

Quarantine is lifted only after measures established by law have been taken. The standard period is 1 month.

For 6 months, pigs located in the area affected by the epidemic cannot be sold. Trade in meat is prohibited, as is the export of animals outside the zone.

It is allowed to purchase new pigs only after a year has passed since the epidemic.

The ASF virus is a deadly threat to pets. In addition, the disease harms the development and functioning of the economy. Despite the lack of salvation from this disaster, it is within the power of every farmer to take preventive measures. This is the only way to prevent the spread of infection and save the lives of those under care.