African swine fever ASF. Measures to combat the spread and prevention. ASF in the Voronezh region

African swine fever (lat. Pestis africana suum), African fever, East African plague, Montgomery's disease - highly contagious viral disease pigs, characterized by fever, cyanosis of the skin (bluish coloration) and extensive hemorrhages (accumulation of blood that has poured out of blood vessels) in internal organs. Listed as A (Highly Hazardous) according to International classification contagious animal diseases.

First recorded in 1903 in South Africa.

African swine fever virus is a DNA-containing virus of the Asfarviridae family; the size of the virion (viral particle) is 175‑215 nm (nanometer - a billionth of a meter). Several seroimmuno- and genotypes of the African swine fever virus have been established. It is found in the blood, lymph, internal organs, secrets and excretions of sick animals. The virus is resistant to drying and decay; at 60°C it is inactivated within 10 minutes.

The incubation period of the disease depends on the amount of the virus that has entered the body, the condition of the animal, the severity of the course and can last from two to six days. The course is divided into fulminant, acute, subacute and less often chronic. With a lightning current, animals die without any signs; in acute - in animals, the body temperature rises to 40.5-42.0 ° C, shortness of breath, cough, attacks of vomiting, paresis and paralysis appear hind limbs. There are serous or mucopurulent discharge from the nose and eyes, sometimes diarrhea with blood, more often constipation. Leukopenia is noted in the blood (the number of leukocytes decreases to 50‑60%). Sick animals lie more, buried in the litter, sluggishly rise, move and quickly get tired. Weakness of the hind limbs, unsteady gait, the head is lowered, the tail is untwisted, thirst is increased. On the skin in the area inner surface hips, on the abdomen, neck, at the base of the ears, red-violet spots are noticeable, they do not turn pale when pressed (pronounced cyanosis of the skin). Pustules (abscesses) may appear on tender areas of the skin, in place of which scabs and ulcers form.

Numerous hemorrhages are found in the skin, mucous membranes and serous membranes. The lymph nodes internal organs are enlarged, look like a blood clot or hematoma. Internal organs, especially the spleen, are enlarged, with multiple hemorrhages.

The diagnosis is made on the basis of epizootological, clinical, pathoanatomical data, laboratory tests and bioassays.

In the event of a focus of infection, the total destruction of the sick pig population is practiced. bloodless method, as well as the elimination of all pigs in the outbreak and a radius of 20 km from it. Sick and in contact with sick pigs are to be slaughtered, followed by incineration of corpses. Manure, leftover feed and low-value care items are also subject to incineration. The ashes are buried in pits, mixing it with lime. The premises and territories of farms are disinfected with a hot 3% solution of sodium hydroxide, 2% formaldehyde solution.

A quarantine is imposed on a dysfunctional farm, which is removed after 6 months from the date of slaughter of pigs, and breeding of pigs in a dysfunctional point is allowed no earlier than a year after the removal of quarantine.

Owners of private farms in which there are pigs must follow a number of rules, the implementation of which will preserve the health of animals and avoid economic losses:

Provide livestock of pigs for vaccinations carried out by the veterinary service (against classical swine fever, erysipelas);
- keep the livestock only closed, do not allow the free range of pigs in the territory of settlements, especially in the forest zone;
- every ten days to process pigs and a room for their maintenance from blood-sucking insects(ticks, lice, fleas), constantly fight rodents;
- do not import pigs without the consent of the State Veterinary Service;
- do not use non-decontaminated feed of animal origin, especially slaughterhouse waste in the diets of pigs;
- limit ties with disadvantaged territories;
- immediately report all cases of disease in pigs to the state veterinary institutions in the service areas.

The material was prepared on the basis of information from open sources

African swine fever (ASF) primary distribution site — South Africa hence the name of the disease. Another name is Montgomery's disease. First diagnosed disease of the 20th century. In stages, the virus was transferred to Portugal, Spain and various countries in the Americas. Toward the end of the century, the active spread of the disease among wild animals began. The infection then spread to domestic livestock.

ASF is a disease of an infectious type of excitation. Causes fever, various inflammatory processes, necrosis and diathesis and other manifestations.

The disease is fatal, and there are not many animals in the home that produce antibodies and survive the disease. Dead pigs have some characteristic features in the structure and pathological changes in organs:

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

The symptoms of the disease are similar to the standard fever, but the causative agent is completely different. The virus that causes inflammation is Asfivirus, belonging to the Asfarviridae family. To date, the virus has already managed to mutate somewhat and seroimmune ASF genotypes are isolated.

The ASF genome is extremely resistant to all types of influences, it is not destroyed by acid pH from 2 to 13. It survives with a large number of temperature changes. It tends to retain the ability to reproduce even when dried, crystallized due to low temperature and decay. The virus survives even with prolonged storage of meat in the freezer or rotting of the flesh. The only available way to destroy bacteria is heat treatment at high temperature.

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

Methods of infection

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

Among the carriers of the virus can be various animals and even people. So birds, small rodents that feed on leftover feed 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. Also directly infected pigs themselves are carriers of the disease.

Consequences of ASF - death

Bacteria-causative agents can persist in waste products, feed for a long time. From 1 infected individual, a whole pasture can become unusable, since the virus is extremely aggressive and spreads extremely quickly.

Dependence of age, gender, breed or other indicators on the risk of infection is not observed. All animals are susceptible to ASF. There are times when you have to destroy entire factories 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 first manifestation.

The disease may have different shape, so they distinguish:

Acute - the animal is quickly exposed to symptoms and soon dies. At the same time, the pig's temperature rises to 40.5 - 42 ° C, sluggish, weak condition, 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. Indigestion in the form of constipation, vomiting, diarrhea with particles of blood clots. The skin has bloody discharge, often appearing on the ears, neck, especially lower section, on the abdomen and perineum. Usually accompanied by pneumonia. Progression of the disease within 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;
Super-sharp - the individual almost certainly dies and in a short time. The lethal outcome is instant, even the symptoms do not have time to manifest themselves;
Subacute - the gradual spread of foci of the disease, the manifestations are similar to the acute form, but to a lesser extent. The pig experiences bouts of fever, lack of appetite and a general breakdown. Death occurs within 2-3 weeks, the cause of death is heart failure;
Chronic form - the animal has permanent signs ASF, but with moderate symptoms. Often occurs against the background of infections of bacterial origin. Breathing becomes difficult, the animal is in a fever, the wounds do not heal. Physical exhaustion sets in and the individual lags far behind in development. At the same time, the synovial membranes, tendons have pathological deviations in the structure.

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

Diagnosis of African plague

The first characteristic feature of ASF is the appearance of cyanotic spots, sometimes blood streaks 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 that he consumes, water. Nothing to do with other animals should not be.

Then it is necessary to examine the rest of the 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, as this is a risk for the entire region of residence, otherwise the infection will spread through insects into an epidemic.

The next step in diagnosis is to determine the type of infection, the source of African plague infection.

To determine the pathogen, it is necessary to conduct biological tests, laboratory studies. So in the process of examination, not only the virus is detected, but also the antigen. The antibody test 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 high level 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 - this is a fairy tale. The only way out until today is the complete destruction of infected individuals and everything associated with them.

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

Video - African swine fever

Scientists are constantly looking for a vaccine against the virus, but as soon as they get closer to discovery, the virus mutates. The constant change in the structure leads to the impossibility of determining its vulnerability and the implementation of treatment. Since the onset of the plague and about 10-20 years ago, all cases of infection have ended lethal outcome. Today, more and more often there is a spillover of the disease into chronic form and its asymptomatic manifestation, so you should not count on visible symptoms.

The main opportunity to save the livestock is a thorough examination of the animals. Permanent, regular procedures allow you to notice the disease in a timely manner, if there are symptoms. Otherwise, only examinations can show the virus. So, if you keep animals in different cages and minimize the contact of individuals, you can avoid mass infection, but this is if you're lucky. Since the virus spreads extremely quickly and easily, it is quite difficult to prevent its spread.

All individuals are placed in quarantine and held various tests. If it was possible to determine that they are infected with ASF, the animals are destroyed.

Measures after the discovery of the virus

Today, effective measures to prevent the spread of the ASF virus within the livestock simply do not exist. The best recommendations by today's standards should be followed, namely: to restrain further spread, to minimize the risk of infecting other animals, to suppress outbreaks of plague until the onset of an epidemic.

If an outbreak of ASF is detected, all livestock should be destroyed. In this case, the blood is first removed. Household items with which pigs come into contact, contaminated feed are burned along with the corpses. 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%).

Approximate, to the place of the outbreak, animals are at risk, so they are cut. The meat is fit for consumption, but after heat treatment, make canned food. Cleanup area - 10 km. The entire region is under quarantine. It lasts about 6 months from the moment of the last outbreak and death of pigs. The territory for pasture and keeping of livestock is unusable for 1 year after the quarantine is lifted, and requires verification 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, and not only from the African plague virus, but also various others.

How does ASF threaten people?

Most medical and sanitary epidemic stations agree that this species 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 at the stage of mutation, so it is rather 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 of an economic kind. Mankind is experiencing high costs for the destruction of a huge number of pigs and the implementation of 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, the losses amount to 30 billion rubles. All over the world, the extent of disease and losses can only be guessed at.

Research on the danger of the virus to humans

Not all scientists are so optimistic, there have been various studies that have disturbing findings about the effects on humans. Despite the absence of diseases of the virus in humans, there are documented reactions to the production of antibodies against it. This indicates a hit, 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 a greater genetic diversity of the virus than previously known.

It is also noted that no one has conducted mass research to search for the ASF virus in humans, since there are simply no symptoms. Despite the absence of obvious symptoms, this does not indicate the complete health of a person and the absence of the possibility of infection. The main action of bacteria is immune in nature, it is this system that is destroyed in pigs during illness.

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 who could not establish the etiological component of the virus. So 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 determining the etiology of ASF disease. Most importantly, risk ASF disease still exists, but it is rather difficult to determine it. The plague can infect a person and even lead to his 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 (and others) point to the risk of the disease to humans. In general, the ASF virus, despite its long history, is still poorly understood and the search for an effective remedy is ahead.

Conclusion

Video - conclusion on the end of quarantine

For humans, ASF is considered a harmless virus. Even when purchasing infected meat, no one eats it raw, cooking at a temperature of 70 ° C and above destroys the pathogen. Neglecting security measures and selling infected meat is strictly prohibited, as this can provoke an epidemic worldwide in pigs. The high adaptive ability of the virus has been noticed for a long time, so the further development of the disease must be stopped and localized at the origin.

(ASF) (lat. Pestis africana suum), African fever, East African plague, disease Montgomery- acute viral infection pigs, endemic to Africa and certain countries of Central and Eastern Europe.

Problem. African swine fever is a highly contagious disease and can spread very quickly in the pig population through direct or indirect contact. The virus can persist for a long time among pigs, persist in pig products or in the environment, and, once ingested by wild boars and Ornithodoros ticks, becomes endemic to the area. Virus strains African swine fever can vary from highly virulent, causing 100% mortality, to low virulent isolates, which makes the diagnostic process difficult.

For humans and other animal species African swine fever poses no danger.

Vaccines and treatments this disease does not currently exist. Speculation around the topic of availability effective vaccine against ASF at the current stage of development of vaccinology is untenable.

African swine fever is a serious problem in many countries of Africa, and since 2007 - the countries of the Transcaucasian region and Russia. Sporadic outbreaks have also occurred in Europe, South America and the Caribbean in various years, and the cost of eliminating the disease has been extremely high. During the outbreak of ASF in Malta, in the Dominican Republic, in Cuba, it was possible to stop and eliminate the infection only thanks to the complete destruction of the pig population. In Spain and Portugal, ASF has been endemic since the 1960s and it took more than 30 years for these countries to achieve free status.

Changes in production technology, globalization, the most difficult situation for the control of this infection in Russia increase the risk of penetration African swine fever to the territory of Ukraine. The penetration of this infection can threaten the pig industry as an industry.

Etiology. The causative agent of African swine fever belongs to the Asfivirus species of the Asfarviridae family. This is the only representative of DNA viruses, the carriers of which can be arthropods.

All species of the pig family (lat. Suidae) are susceptible to the virus - the family of non-ruminant artiodactyla (Artiodactyla), which includes 9 species combined into 5 genera, both wild and domestic. The degree of pathogenicity may vary depending on both the virulence of the strain and the species of the animal.

Geography of the pathogen. The disease is endemic to most of Africa, including the island of Madagascar. Most common in the equatorial zone. Periodically, due to the introduction of the disease, outbreaks occur in various regions with intensive pig production and on other continents.

Within the territory of former USSR ASF was registered in 1977. As a result of infection through Odessa ports, 3 large epizootic outbreaks of the disease took place - in Odessa ( primary focus), then in Kyiv (secondary focus) and Sverdlovsk (tertiary focus) regions. But thanks to the timely and competent work of veterinary specialists and state support for anti-epizootic measures, all three outbreaks were eliminated in as soon as possible.

Currently, wild pigs of Sardinia and Italy are considered endemic for ASF, and since 2007 - animals of the Caucasus region and the southern federal district of Russia.

The main ways of distribution of ASF. Pathogen African swine fever can be transmitted through direct contact (oral-nasal route) between animals, through objects and products that have had contact with an infected object, but ticks are the most dangerous vector of transmission. The virus persists in all body tissues; the largest amount is found in the blood. Mass pollution of the external environment can occur during the traditional slaughter of pigs or secretions (bloody diarrhea) of sick animals, which poses a danger to the contamination of premises, transport, equipment and feed. It is not uncommon for cases when re-infection occurs when pigs eat food waste that has not undergone heat treatment from products exported illegally from the source of the disease. It has been confirmed that the ASF virus is highly resistant in the external environment and can remain infectious for more than 1.5 years in the blood at +4°C, 11 days in faeces at room temperature, for months on farms after the elimination of diseased pigs, up to 150 days in chilled meat, up to 140 days in ham (Spanish ham), for years - at temperatures below zero.

Transmissible through ticks Ornithodoros spp. The ASF virus is transmitted by a bite. Between ticks, transmission can occur in a horizontal and vertical way, this is the main problem of the endemicity of the disease, when the virus in a colony of ticks circulates for years without contact with sick animals.

The possibility of mechanical transmission of the virus by other blood-sucking insects (mosquitoes, horseflies) within a few days after contact with a sick animal has been proven.

The most important routes of infection with the ASF virus are:
unauthorized transportation of infected animals and unheated pig products;
infected feed, including food waste;
in nature: wild boars and ticks of the endemic zone.

A detailed epizootic cycle of ASF is shown in Fig. one.
incubation period. When a healthy animal comes into contact with a sick incubation period lasts 5-20 days, but with a tick bite it may be less. Acute stage The disease manifests itself after 5-7 days and always ends fatally.

Clinical signs. The disease occurs in hyperacute (lightning fast), acute, subacute and chronic forms. Highly virulent strains cause hyperacute and acute forms and infect the entire livestock of the farm in a few days. Weakly virulent strains do not give a vivid picture of the disease, which sometimes makes it difficult to make a diagnosis, but in any case, all animals of the herd are affected within a few weeks.

Sudden death in the absence of visible lesions characterizes the hyperacute form and may be the first sign of infection circulating in the herd. The acute form is characterized high fever(With concomitant consequences), moderate anorexia, lethargy, weakness, stagnation of animals, erythema.

In some sick pigs, cyanotic staining of the skin of the ears, neck, and extremities is noted. On palpation, an abdominal pain reaction is manifested, from the gastrointestinal tract - constipation or diarrhea, initially mucous, then bloody. Generalized hemorrhages are revealed on the skin and internal organs. Pregnant sows are aborted. A blood test shows leukopenia. Death occurs 7-10 days after the onset of the first symptoms.

Clinical signs in the subacute form of ASF are similar to the clinic of the acute form of the disease, but are extended in time and not so severe. Mortality is much lower in adults. The disease is characterized by fever, thrombocytopenia, leukopenia, and affected pigs usually die within 3-4 weeks. However, the clinical signs, as in the case of the chronic form, are not typical, they can easily be confused with infections such as classical swine fever (CSF), erysipelas, salmonellosis and pasteurellosis. Clinically, the disease cannot be distinguished from CSF, therefore, the entire population of pigs must be vaccinated against CSF without fail, and any disease of animals with a clinic similar to CSF must be considered as ASF with the ensuing measures and possible consequences.

pathological changes. Numerous epidermal hemorrhages, hemorrhages on mucous membranes and serous membranes. The lymph nodes of the internal organs are enlarged, look like a blood clot or hematoma. In the chest and abdominal cavities - serous-hemorrhagic exudate with an admixture of fibrin and blood. The internal organs, especially the spleen and kidneys, are enlarged, with multiple hemorrhages. In the lungs - interlobar edema. Histological examination reveals a characteristic strong disintegration of the chromatin of the nuclei of lymphocytes in the tissues of the reticuloendothelial system, karyorhexis of the liver tissues.

Diagnosis. Diagnosis is complex and confirmed by laboratory using direct and indirect methods.

Before taking and sending samples from animals suspected of being infected with the ASF virus, it is necessary to inform the superior veterinary service! Patient samples are sent by courier, under the strictest biosecurity conditions, and only to specialized laboratories in order to avoid the risk of spreading the pathogen.

Prevention and control measures. effective means prevention of ASF has not yet been developed, treatment is prohibited. In the event of a focus of infection, the total destruction of a sick pig population by a bloodless method is practiced, as well as the elimination of all pigs within a radius of 10 km from it. Sick and in contact with sick animals, pigs are to be slaughtered, followed by burning of corpses. Importation of new livestock into the farm is allowed only one year after the elimination of the disease.

Causes contributing to the occurrence of ASF (on the example of the Rostov region, Russia):
lack of proper protection of pig farms from the introduction of pathogens of infectious diseases;
lack of proper control over the health of animals;
lack of proper control over the movement of animals and products of animal origin;
violation by the administration and personnel of farms of veterinary and sanitary rules;
free grazing of pigs;
untimely diagnosis of the disease;
untimely adoption of measures to stop and eliminate ASF foci, slaughter or destruction of pigs in a disadvantaged point and the first threatened zone;
concealment of the disease;
lack of proper measures to account for livestock;
non-monitoring of ASF in neighboring states;
the maintenance of pigs in a personal subsidiary plot by workers of pig farms.
To prevent the introduction of the disease into the territory of Ukraine, it is necessary to follow a number of rules,
the implementation of which will preserve the health of animals and avoid economic losses:
a regime of veterinary and sanitary isolation with countries affected by ASF, and control over any transportation of pigs and swine products within the country;
the strictest accounting of the number of pigs;
total shooting of the livestock of wild boars in the border areas;
providing livestock of pigs for vaccinations carried out by the veterinary service (against classical swine fever, erysipelas);
keeping livestock on farms only in a closed mode, preventing the free range of pigs
small farms in the territory of settlements, especially in the forest zone;
ten-day treatment of pigs and premises for their keeping from blood-sucking insects (ticks, lice, fleas), constant control of rodents;
a ban on the importation of pigs without the consent of the State Veterinary Service;
a ban on the use of feed of animal origin without thermal treatment in the diet of pigs;
the supply chain for meat products should come only from prosperous countries and regions;
immediate reporting of all cases of death of pigs to the state veterinary institutions in the service areas.

In the event of ASF, a quarantine is imposed on a dysfunctional farm. All pigs in this focus of infection are destroyed in a bloodless way. The corpses of pigs, manure, leftover feed, low-value care items are burned. The ashes are buried in pits, mixing it with lime. The premises and territories of farms are disinfected with a hot 3% solution of sodium hydroxide, 2% formaldehyde solution.

Within a radius of 10 km around the unfavorable point, all pigs are destroyed, and the meat is processed into canned food.
Quarantine is removed 6 months after the last case of a case, and breeding of pigs in a disadvantaged area is allowed no earlier than a year after the quarantine is lifted.

Possible consequences of the spread of ASF in 2010 If the situation with the limitation of the spread of ASF in Russia is not radically changed, the entire territory of the Southern Federal District of Russia (UFOR) will become permanently affected by ASF. The infection will be carried outside the EUFOR and will continue to spread throughout Russia (there are already cases of the pathogen being introduced into the Leningrad and Orenburg regions), which poses a huge threat of the pathogen being introduced into Ukraine. In this regard, the transfer of the entire pig breeding and meat processing enterprises of the country to the “closed” regime is fully justified.

Only with the joint work of the Veterinary Services of all countries is it possible to stop such a terrible threat to pig production as ASF, the damage from which cannot be compared with any other losses in animal husbandry.

African swine fever, or ASF for short, is an infection. After infection, the animals begin to have a fever, turning into hemorrhagic diathesis and leading to organ necrosis.

African swine fever is an infection that is dangerous to animals and humans.

The disease itself is not well understood. ASF was first described during a case livestock in South Africa at the beginning of the last century. Wild boars are believed to be the source of the infection. From Africa, along with infected pigs, the virus moved to Portugal, immediately spreading to the livestock of Spanish farmers. After the Second World War, ASF confidently walked through the countries of Latin America and by the end of the twentieth century reached Asia, from where it confidently stepped into Eastern Europe.

In Russia, the first outbreak of the African plague epidemic took place in 2007. More than 500 foci of the disease were recorded and more than a million heads of livestock were destroyed. Pastures and food waste added to top dressing became the source of the spread of the infectious virus.

At the moment, the nature of the causative agent of ASF has been accurately determined. This is a genetic virus from the Asfarviridae family that can mutate and change, adapting to the conditions, unlike the causative agent of the usual classical plague - a virus from the Flaviviridae family.

The causative agent of ASF is resistant to factors such as:

temperature range, does not die when frozen;
rotting, so the dead livestock must be burned;
Drying. The virus remains active, because of this, infected pastures cannot be used, even after droughts or burning.

This virus was first detected in South Africa, but quickly spread throughout the world.

Signs of the disease

In laboratory conditions, the African swine fever virus manifested itself as follows:

incubation period from 5 to 20 days;
four types of the course of the disease: acute, hyperacute, subacute and chronic.

However, according to practical observations in real conditions, the incubation of ASF can last up to 3-4 weeks, while an animal that is externally affected by the virus will not differ in any way from a healthy one.

Signs of African swine fever depend on the form in which the disease occurs. It, in turn, directly follows from the subspecies of the causative agent of infection.

Signs of the disease depend on which form of ASF the animal is ill with.

Acute

The incubation period of this form, according to observations, lasts from a day to a week. Then they appear:

a sharp increase in temperature to 42 degrees;
purulent whitish discharge from the nostrils, ears and eyes, with a pungent odor;
the oppressed state of the animal, indifference and weakness;
pronounced shortness of breath;
paresis of the hind legs;
vomit;
diarrhea with blood, followed by constipation;
on thin areas of the skin - behind the ears, on the stomach, under the jaw, bruises, black bruises suddenly appear.

The acute form of ASF is accompanied by sharp deterioration condition of the animal and quick death.

Quite often, at the very beginning of the progression, the African plague is accompanied by pneumonia, perhaps disguised as it. Pregnant sows will inevitably abort when infected.

The illness lasts for a maximum of a week. Immediately before death, a sick pig's body temperature drops sharply, it falls into a coma, almost immediately agonizes and dies.

Super sharp

The most insidious form of this disease. The clinical picture is completely absent, there are no signs of ailments. Animals don't even cough. They just die. Suddenly and instantly. According to the farmers, she stood, ate, fell, died.

subacute

With this variant of the development of the disease, the pig is sick for up to a month, the incubation period is not exactly defined. The animal shows:

temperature jumps;
depressed state;
bouts of fever;
cardiac disorders.

The subacute form of ASF is difficult to diagnose, as it has symptoms similar to other common diseases.

At the first sign of this form of the virus, farmers usually begin to treat the animal in the same way as for pneumonia or fevers, without realizing for a long time that the pig has become a victim of ASF. Literally until the mass case begins.

As a rule, with this form of ASF, pigs die unexpectedly, as a result of heart failure or rupture of the heart.

Chronic

Incubation is not defined, the disease itself is extremely difficult to diagnose. The fact is that in the chronic form, the plague pathogen is masked by a whole bunch of secondary bacterial infections.

The clinical picture in this form is characterized by:

difficulty in breathing;
rare attacks of fever and cough;
violations of cardiac activity;
ulcers and wounds on the body that do not heal, outwardly similar to trophic ulcers of people;
the animal is significantly behind in weight gain, if the piglet is sick, then a general developmental delay is evident;
tendovaginitis often develops due to virus damage to the synovial membranes;
the inflammatory process in the tendons leads to the appearance and rapid progression of arthritis.

In the chronic form of the disease, the plague pathogen masquerades as other bacterial infections.

The virus seems to be hiding under successive obvious and easily diagnosed infections. It is logical that farmers begin to treat those diseases that they themselves and livestock specialists see. Animals are treated for inflammation, vaginitis, arthritis, heart disease, even the flu. At the same time, verified and effective treatment doesn't give any results. This is the very first reason to be alert and test for African plague.

In the chronic form, diagnose true reason livestock death, unfortunately, usually succeeds only posthumously, during clinical research in places where livestock die. The duration of the disease in this form is also not precisely defined. Infected pigs die either from one of the visible infections or from cardiac arrest.

Disease diagnosis

Timely diagnosis is difficult, because quite recently no one simply knew what the African plague is. Accordingly, sufficient statistical data have not been accumulated, and a complete laboratory picture of the course of the disease has not been revealed. The external similarity of ASF with classical plague also makes it very difficult to properly respond to the situation. Measures taken against a common plague agent are useless when confronted with a native of South Africa.

The main points identified so far that farmers should be concerned about are:

the appearance of cyanotic spots on animals. This is the most accurate indicator for the breeder that you need to play it safe and call the veterinary service;
change in behavior, lethargy, lethargy - a reason to isolate the animal;
cough . If there are concerns about the possibility of contracting the plague, this is an occasion to full examination pigs;
clouding of the membrane of the eyes almost always precedes the release of pus, that is, portends an acute form of ASF.

To diagnose the disease, a comprehensive examination of the entire population of pigs is carried out.

What will the Veterinary Services do?

comprehensive examination of pigs;
clarification of the ways of infection in case of confirmation of the diagnosis during the period of clinical trials and observation of the development of pathology;
biological samples will be taken:
analyzes for antibodies, the presence of which on given time- this is the main factor confirming the presence of the virus;
carry out laboratory tests to accurately determine the subspecies of the infectious agent for further antigen production;
designate a zone where strict quarantine will be introduced.

In fact, African swine fever is a death sentence for animal husbandry. It will not be possible to save the animals, and the steps taken by veterinarians will only help to avoid further spread of the virus.

Treatment for ASF

There is currently no cure for this scourge. The symptoms of African swine fever are not clear, especially since there are no drugs that can stop the constantly mutating virus.

Currently missing effective drugs capable of curing an animal from ASF.

Moreover, the situation around this disease is rather ambiguous. Attempts to cure animals with this diagnosis are officially strictly prohibited, sick pigs are subject to immediate bloodless destruction and further disposal.

This position is dictated by the extreme danger of the pathogen, the lack of drugs whose effectiveness would be confirmed at least by laboratory tests, and a number of other factors.

It should be noted that studies conducted on African swine fever are under special control of the state, and they are a priority today, since it is this virus that leads to the most serious economic losses in animal husbandry.

But until a vaccine exists, farmers are left to try to avoid infecting their livestock and take preventive measures.

Ways of infection

The following options for the transition of the virus and its penetration into the body of a pig are assumed:

on contact;
through transmission;
through mechanical carriers.

Contact of a sick animal with a healthy one allows the pathogen to pass through the mucous membranes. oral cavity, cracks on skin, livestock waste products, common feeders and drinkers.

The disease is transmitted through animal contact, insects and mechanical vectors.

Transmissibly, the disease is transmitted through insects that carry viruses, including plague. Bites of ticks, horseflies, zoophilous flies, even fleas can be dangerous and become a source of infection. Contact with ticks is especially fraught with consequences.

Mechanically, the pathogen can be carried by small rodents, that is, mice and rats; cats, dogs; birds, both domestic, such as geese or chickens, and the "neighbors" of man: one crow is quite capable of infecting an entire pigsty. The source of the disease for pigs, that is, the carrier of the African plague genome, may well be a person who has visited the places of the epidemic.

According to the observations of farmers, during the outbreak of the epidemic in 2007-2008, succumbing to panic, many called the veterinary services for no particular reason. And after the visit of livestock specialists, the slaughter of livestock began. Today, fortunately, much more is known about the virus, and such a development of events is excluded.

Preventive measures

African swine fever, as already mentioned, is not well understood, but the main recommendations for preventive measures yet defined. Any disease, and plague is no exception, implies two directions for prevention:

measures against the spread of infection;
measures to prevent infection.

To prevent further spread and localize the focus of the epidemic, the following should be done:

all animals in the contaminated area are subject to immediate destruction;
inventory items used in caring for livestock are burned;
animal corpses are disposed of only by burning, the ash is mixed with lime and buried;
feed on the farm is burned;
pastures are burned out, then treated with hot solutions;
buildings of pigsties, the entire surrounding area, if possible, are calcined and in any case treated with a hot solution of 3% sodium and 2% formaldehyde;
within a radius of 10 km from the identified outbreak of ASF, the strictest quarantine is declared for at least 6 months from the moment of destruction of livestock and processing of territories;
animals located beyond the line of the quarantine area within a radius of several kilometers (more precisely determined on the ground depending on the immediate topographical conditions) are immediately slaughtered exclusively for canned food, any other production or processing will entail criminal liability;
the area where the virus is detected cannot be used for keeping and raising livestock for at least a year after the end of the general quarantine, but even after this, a permit will be required veterinary services after taking all the necessary biological samples.

Strict preventive measures must be taken to prevent a pandemic.

To prevent African swine fever, aimed at preventing an epidemic, they resort to the following actions:

The question of the advisability of all kinds of vaccination of pigs in the circles of livestock breeders causes fierce controversy. After all, no vaccination will protect the animal from ASF. The argument that vaccinations will boost immunity is countered by counterarguments that even if the pig stays healthy while the other gets sick, both will have to be destroyed. So what's the difference whether the animal's immunity will increase or not?

Is swine fever dangerous to humans?

According to all practical observations and laboratory research currently known strains of the African swine fever virus do not pose any threat to human health. The meat of a pig carrier of the virus during heat treatment above 80 degrees also does not pose any danger. That is why pigs outside the zone of direct quarantine, whose infection is in question, are slaughtered for canned food.

But in connection with the very recent events in the Crimea - with the localization of the focus of the African swine fever epidemic there and, possibly, the discovery of a new strain of the virus, which has not yet been encountered in our country - the main veterinarian Russia expressed concern that the constantly mutating ASF genome could become dangerous for humans in the future.

Now ASF is safe for humans, but the virus is constantly undergoing mutation.

At the moment, the harm to people from this disease in livestock is manifested only in economic losses. After all, the strictest quarantines, the destruction of livestock and the impossibility of using infected territories, as well as the rupture of trade relations and contracts for the supply of pork and livestock products and breeding with the countries through which the African plague has swept - all this causes tangible blows both to the economy of the state as a whole, and, in particular, to animal husbandry, and to wallets ordinary people. Since it causes a rise in the price of meat and meat products directly in the markets and in stores.

Summarizing, it should be noted that over the ten years that have passed since the first epidemic of African swine fever in Russia, which caused terrible economic losses, the situation regarding this swine disease has changed.

Today, superacute and sharp forms epidemics. Most affected pigs suffer from chronic type infection development. And this speaks not so much about ASF mutations, but that the immunity of boars increases, and their own organisms, while transmitting information about the genetic threat to their descendants, they still form antigens.

In general, the forecast for the emergence of a vaccine and the successful fight against this disease in the future is quite optimistic.

African swine fever (Pestis africana suum), also known as Montgomery's disease, African or East African fever is considered one of the most dangerous and merciless, since when acute course in animals ends with a 100% death and brings enormous economic damage.

The ASF virus is not transmitted to humans– no cases of direct infection have yet been registered in the world, however, some studies confirm the presence of antibodies to this virus produced in the human body.

ASF in pigs is characterized by fever, multiple hemorrhages, inflammatory, degenerative and necrotic changes in various organs and tissues, leading to high mortality.

Many consumers are concerned about: how dangerous is African swine fever for humans and what happens if you eat infected meat? According to experts, people are not infected with the ASF virus, and eating meat products that have been heat-treated at temperatures above 70 ℃ does not threaten anything. However, this is not recommended in order not to spread the infection to other pigs through the food waste fed to them.

Etiology of the disease

The causative agent of the disease is DNA-containing virus (family of iridoviruses), which multiplies in the cytoplasm of cells, inhibiting the synthesis of DNA, RNA and proteins. Recovered animals do not acquire immunity and remain virus carriers, while the virus accumulates in all organs and systems, primarily in the blood. In the external environment, it is extremely resistant to a wide range of temperatures, pH changes, drying, decay and remains active:

In a cold dark room with a temperature of about 5 ℃ (in the refrigerator), the virus is able to maintain its infectious properties for 6 years.

Scientists have not yet been able to find treatments and develop a vaccine to prevent ASF.

The main epidemiological feature of the African swine fever virus is change in the course of infection: from hyperacute to latent (asymptomatic) with constant mutations that increase genetic diversity, as well as the impossibility of identifying the pathogen without a special examination.

An epizootic is the simultaneous mass spread of a disease among animals of one or more species over a large area (the same as an epidemic in humans).

Ways of transmission of the virus

To the disease wild and domestic pigs of all breeds and ages are susceptible, including decorative ones. In wild animals in nature, ASF is often asymptomatic, so they are the main source of the spread of the virus.

The infection spreads from sick and recovered animal carriers through secretions (blood, feces, urine, saliva, etc.) that enter the air, soil and water. In many cases the cause of infection was the products of slaughter of infected pigs- food and slaughterhouse waste used without proper heat treatment for feeding livestock.

For the first time, the disease was described in detail by the English researcher R. Montgomery (1921), who studied it in Kenya and proved viral nature this infection. long time outbreaks were recorded only in the southern equatorial countries of Africa, but in 1957 ASF came to Europe, and then to Cuba and Brazil. Since then, the disease has become widespread geographical distribution. Livestock breeders in Russia came face to face with African swine fever in 2007. To date, according to the Rosselkhoznadzor, open outbreaks are observed:

In the period from 2012 to 2018, outbreaks of African plague were registered in the Baltic States and Poland (mainly in wild boars), Ukraine, Moldova, Slovakia, Romania, etc. low level biosecurity and disease detection capabilities on early stages. The risk of the virus entering the EU through these countries is assessed as very high.

According to statistics published in Ukraine, in 2017, 163 cases of infection with domestic and wild pigs with ASF were detected, and in 2018 - 138, which led to huge losses of livestock and resulted in billions of dollars in losses for the entire livestock industry. Today, pork imports into the country are more than 10 times higher than its exports.

Clinical signs of plague in swine

By outward signs the African plague is difficult to distinguish from the classical one, while the intensity of the manifestation of symptoms largely depends on the form of the course of the disease:

hyperacute course(observed quite rarely) - fever with body temperature up to 42 ℃, general depression. Death occurs in 2-3 days;
acute course- temperature up to 41-42 degrees, conjunctivitis or swelling of the eyelids, hyperemia (redness) of the skin, especially around the eyes, anxiety, increased breathing and heart rate, unsteady gait, serous nasal discharge, pneumonia, cyanosis of the skin and mucous membranes with multiple hemorrhages. Then the discharge from the nose becomes bloody, bloody diarrhea appears, alternating with constipation, convulsions and paralysis of the limbs occur. The duration of the disease is 4-10 days, the outcome is fatal;
subacute course- according to the clinical picture, it is similar to acute, but the symptoms are less pronounced and develop for a longer time (15-25 days). Often complicated by salmonellosis or pasteurellosis. Most animals die, in surviving individuals the disease becomes chronic, and they become virus carriers;
chronic course- the skin becomes cyanotic, necrosis develops on it, in subcutaneous tissue soft (non-painful) swelling is formed, fever is periodically manifested. It lasts on average from 2 to 10 months, after which most animals die from exhaustion and inflammatory processes, mainly bronchopneumonia;
asymptomatic course(latent form) - more often observed in wild African pigs (warthogs, bush, giant forest), as well as in domestic pigs by the end of the epizootic. In the absence of external symptoms of the disease, animals become virus carriers.

Methods laboratory diagnostics African swine fever are approved by the interstate standard (GOST 28573–90), introduced since 1991. The diagnosis is established based on the results of studies of samples of biological (pathological) material and blood sera in the detection of the ASF virus, its genetic material or antibodies to it.

Upon confirmation of the diagnosis pig treatment, virus-infected ASF, prohibited. Sick animals are subject to complete destruction.

Basic measures to eliminate outbreaks and prevent the spread of ASF

All measures to combat ASF in Russia are regulated veterinary regulations adopted by the Ministry of Agriculture (Order No. 213 of 2016).

Prevention

To prevent infection of pigs with the African swine fever virus, it is necessary:

comply with veterinary rules for keeping animals;
prevent pollution environment animal waste;
in cases of sudden death, appearance clinical signs or in case of suspected infection of pigs with the ASF virus, notify the specialists of the state veterinary service within 24 hours;
ensure the isolation of sick and dead pigs, as well as pigs in contact with them, in the same room where they were kept;
follow the rules of restrictive (quarantine) measures;
when a focus of infection is detected, ensure the free-range keeping of pigs in other farms in the adjacent territories.

Also, for the purpose of prevention, it is recommended to monitor the quality of purchased feed, not to use waste, especially those that have not undergone proper heat treatment ( ASF virus is inactivated at 60℃ in 10 minutes, and when boiling almost instantly). Regularly process the premises in order to destroy rodents and insects, disinfect equipment and vehicles, conduct scheduled veterinary examinations and animal examinations.

When buying piglets or adult pigs, especially in regions with an unfavorable epizootic situation, it is important to pay attention to the availability of veterinary certificates and vaccination passports for animals.

Quarantine

To prevent the spread of this contagious disease, in cases of confirmation of the diagnosis, quarantine is introduced, determining in the prescribed manner the boundaries of the outbreak itself and threatened zones, and strict measures are taken to eliminate infected animals. All livestock of pigs located in the outbreak is destroyed by a bloodless method, their corpses, as well as slaughter products, feed residues, containers, dilapidated premises, feeders, inventory, wooden floors, partitions and hedges are burned. If it is not possible to burn it, they bury it to a depth of at least 2 meters. Infected objects are disinfected three times a day, disinsection, decontamination and deratization are performed (treatments to kill insects, ticks and rodents).

In the first threatened zone(on the territory immediately adjacent to the focus of infection, with a radius of at least 5 km) immediately take into account all pigs available in farms of any category, purchase them from the population and, as soon as possible, send them to meat processing plants or slaughterhouses determined by a special commission. Meat and meat products after veterinary and sanitary examination are processed into boiled, boiled-smoked sausages or canned food.

They impose restrictions on the movement of vehicles and people, establish round-the-clock security and quarantine posts (police or paramilitary) on all roads passing through the epizootic focus to external borders threatened zones. Animals detained at checkpoints during inspections are to be slaughtered, and livestock products are to be disinfected and disposed of.

import and export of pigs;
sale of any animals, including poultry, market trade in meat and other livestock products;
holding mass events related to the movement and accumulation of animals.

In the second threatened zone(on the territory adjacent to the first zone, with a radius of up to 100 km from the outbreak) conduct a census of the entire population of pigs and strengthen veterinary supervision for their condition. They impose restrictions on the entry / exit of people and vehicles, the import / export of animals and agricultural products. Control trade and postal items. If necessary, shooting and destruction of stray animals and wild boars is organized in the territories of threatened zones.

Removal of quarantine

After the elimination of the focus of the epizootic, the slaughter of all pigs in the first threatened zone, the implementation of planned measures to decontaminate the virus in the external environment and the provision of a commission conclusion confirming their completeness and correctness, quarantine lifted after 30 days.

Within six months after the quarantine is lifted operate in disadvantaged areas restrictions on:

export of pigs, products of their slaughter, including raw materials;
sale of pigs in the markets and their purchase from the population;
sending parcels containing products and raw materials of animal origin.

Acquisition of farms with a new livestock of pigs in the former focus of the epizootic and the first threatened zone is only allowed in a year since the quarantine was lifted.

Video

How is the fight against ASF carried out in practice, and what do livestock breeders from Volgograd and Tyumen regions, as well as in Ukraine, see the following videos:

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