Sheep bluetongue (febris catarrhalis ovium) (“Blue tongue”, bluetongue). Bluetongue (Blue Tongue, Bluetongue)

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Pathogen

RNA-containing viruses belonging to the genus Orbivirus of the Reoviriday family. The virion size is 68 nm. There are 24 known serovars. The virus is stable in the pH zone 6.5-8.0. Resistant to ether and sodium deoxycholate, sensitive to acetone. In a sick animal, the virus can be detected in the blood, spleen and other organs. The virus is cultivated in mice 1-2 days old, chicken embryos and in lamb kidney cell cultures, BHK-21, where CPE manifests itself.

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Epizootological data.

Under natural conditions, sheep of all breeds are most susceptible to the pathogen, but Merino sheep are more sensitive. Cases of the disease have also been described in cattle, goats, deer, and antelope. Cattle become ill mostly asymptomatically. Infectious bluetongue occurs in the form of epizootics with a large coverage of the livestock (50-60 percent of the herd), characterized by seasonality (warm, wet season) and a more severe course of the disease in animals exposed to solar radiation. Biological vectors of the virus - different kinds biting midges of the genus Culicoides; sheep bloodsucker Melophagusovinus (mechanical vector). During the inter-epizootic period, the virus apparently persists in the body of many species of wild ruminant cattle, among which long-term circulation of the virus has been established (over three years). Being the main reservoir of the pathogen, infected cattle ensure the stationarity of epizootic foci of the disease. In insects, transovarial transmission of the pathogen and transmission during metamorphosis have not been established; they apparently do not take part in the preservation of the virus during the inter-epizootic period. In primary epizootic foci, mortality reaches 90 percent, in stationary ones - 30 percent.

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Pathogenesis

The BLO virus directly affects muscle tissue and internal organs, causing profound changes in blood vessels. As a result, metabolic processes. Animals lose a lot of weight. The disease is usually complicated by secondary infection. The highest concentration of the virus was found between the 5th and 11th days after infection in the spleen, tonsils, and regional lymph nodes, then in the blood (associated with red blood cells). After 6 weeks, the virus disappears from parenchymal organs. Neutralizing antibodies circulate in the blood simultaneously with the virus, which is in high titer. In pregnant females, the virus penetrates the fetus and reproduces in the vascular endothelium, causing hyperemia, impaired permeability and subsequent inflammation. As a result, abortion occurs or malformed offspring are born.

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Course and symptoms

Incubation period under natural conditions it lasts about 7 days, in experiments – 2-18 days. Forms of the disease

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Acute

The acute course is characterized by short-term fever. Usually the temperature rises to 40.5-42°C, the mucous membranes of the oral and nasal cavities turn red, salivation is observed, and bloody mucopurulent discharge from the nasal cavity is observed. Then the epithelium of the mucous membrane is desquamated, the lips, gums and tongue swell, ulcers appear, and stomatitis develops. In some animals the tongue turns dark red to purple or purple, which gave the disease its popular name. Nasal discharge becomes purulent, dries around the nostrils, partially closes the nostrils and makes breathing difficult. The swelling spreads to the muzzle, intermaxillary space, and sometimes to the neck and chest. Pneumonia often develops, diarrhea with blood appears, and skin cracks form. The limbs are affected and lameness develops. Defeat oral cavity And gastrointestinal tract lead to exhaustion. After 3-4 weeks, the hair begins to fall out. In severe cases, patients die within 1-6 days from the onset of the disease. Sometimes, after a visible improvement in the patient’s condition, sharp deterioration and the animals die. This happens 3 weeks or more after the first signs of the disease appear.

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SUBACUTE

When under acute course severe exhaustion, prolonged weakness, slow recovery, and sometimes curvature of the neck are noted. The limbs are often affected, first there is lameness, then purulent processes occur in the hooves, and collapse of the horny shoe. The disease lasts 15-30 days.

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ABORTION

The abortive course of the disease is characterized only by fever and superficial inflammation of the oral mucosa. More often observed in cattle. Recovery occurs relatively quickly. In approximately 5 percent of cattle, anorexia, swelling of the mucous membrane of the eyes, salivation, hyperemia of the mucous membrane of the oral and nasal cavities, and increased body temperature are observed. Ulcers are found on the nasal planum, lips, gums, limbs, udder and vulva. The tongue becomes very swollen and protrudes from the mouth. Difficulty swallowing is then recorded. Animals die from thirst and pneumonia. However, more often BLO in cattle causes abortions and the birth of non-viable, malformed offspring.

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Pathological changes.

The corpse is exhausted. The mucous membranes of the oral cavity and tongue are hyperemic, cyanotic, edematous with the presence of numerous hemorrhages. The epithelium is desquamated, erosions, necrosis, and ulcers are observed on the lips, gums, and tongue. Red gelatinous areas are found under the skin in the neck, shoulder blades and back. Numerous hemorrhages are noted in muscle tissue, small intestine, myocardium, epicardium, mucous membranes respiratory tract, Bladder and ureters.

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Sustainability

virus in external environment quite high. In preserved blood, at room temperature, it is viable for 25 years. At a temperature of 60 C it dies in 5 minutes. Weak solutions of phenol do not neutralize it. Acids, alkalis, and chlorine-containing preparations inactivate the virus.

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Diagnosis.

The disease is established on the basis of epizootic data (seasonality, connection with insect vectors, predominant damage to sheep, occurs in the form of epizootics), clinical signs (fever, damage to the mucous membrane of the oral and nasal cavities, swelling of the head, lameness, hair loss), pathological changes ( necrosis of the mucous membranes, erosions and ulcers in the oral cavity and tongue, hemorrhage in muscle tissue, intestines), as well as according to the results laboratory research- detection of the virus and detection of antibodies in recovered animals. The virus is isolated by infecting mice (intracerebrally), chicken embryos (intravenously), and cell cultures. To clarify the diagnosis, they resort to a bioassay, infecting a healthy sheep intravenously with blood that is suspicious for the disease of the animal. In all cases, virus isolation is confirmed by serological methods. Diffusion precipitation in agar gel, RIF, RSC, RDP are group specific and allow the detection of antibodies to any type of virus; antibodies to the homologous type are detected in the RN and RPGA. An enzyme immunoassay method has been developed for the detection of antigen and antibodies. Bluetongue of sheep should be suspected when fever is detected in animals, inflammatory lesions oral cavity and profuse salivation, taking into account the seasonal appearance of the disease during the period of mass attacks of blood-sucking dipterous insects.

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Differential diagnosis.

Infectious catarrhal fever must be distinguished from foot and mouth disease (high contagiousness, characteristic foot and mouth lesions of the oral cavity, udder, limbs, results virological research), contagious ecthyma of sheep (contagiousness, pustular lesions of the mucous membranes and skin, microscopy of smears from pathological material, bioassay on lambs and rabbits), malignant catarrhal fever(sheep are ill rarely, the disease is mostly sporadic, lesions of the eyes and upper respiratory tract are characteristic), necrobacteriosis (in addition to sheep, horses, pigs and other animals are ill, chronic course, pathogen isolation), Ibaraki disease (cattle are ill, results of virological and serological research), epizootic hemorrhagic disease deer (virological and serological studies).

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Immunity.

Sheep that have recovered from the disease acquire long-term and intense immunity only against the type of virus that caused the disease; against the heterologous type, the protection is weak. Complement-fixing, precipitating and virus-neutralizing antibodies accumulate in the blood. Lambs born from immune sheep remain immune to this disease for 3 months. A vaccine against BLO has been proposed from a virus strain modified by successive passages on sheep, as well as from virus strains passaged on chicken embryos. Immunity in vaccinated sheep appears after 10 days and lasts for at least a year. Abroad and here (V.A. Sergeev et al., 1980) inactivated vaccines have been proposed that are harmless to pregnant ewes and non-reversible. Strong immunity and specific antibodies in high titer remain for at least a year.

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Prevention and control measures.

Infectious catarrhal fever is not registered with us. The main attention is paid to preventing its introduction into our country with imported domestic (sheep, goats, cattle) and wild ruminants. Preventive quarantine is mandatory, with virological and serological studies carried out if necessary. In areas that are permanently unaffected by infectious bluetongue in sheep, it is necessary to vaccinate susceptible livestock at least a month before the onset of the disease season. When a disease appears, vaccination should also be carried out using vaccines against the type of pathogen that caused the disease in a given outbreak. At the same time, measures are taken to protect animals from insect attacks. Restrictive measures are also being introduced.

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Treatment.

No treatments have been developed for animals.

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Bluetongue affects cattle less frequently than sheep. This disease, originally from Africa, is increasingly being recorded in cows in European countries. We will find out what kind of disease this is, how it is dangerous for the animal, how to treat it and what are the preventive measures.

What kind of disease

Bluetongue is also called bluetongue or “blue tongue.” This is a viral infection caused by arthropods. With it, inflammatory-necrotic lesions of the oral cavity, gastrointestinal tract, and hoof skin epithelium are observed.

Did you know? Bluetongue was first discovered in southern Africa in 1876 and was initially considered an African problem. Now this livestock disease is widespread on almost all continents. Outbreaks of this disease have recently been reported in many European countries.

Pathogen, sources and routes of infection

Bluetongue is caused by an RNA virus of the genus Orbivirus (family Reoviridae). The disease can be either isolated or widespread. Its source is sick animals. In transferring this viral infection biting midges from the genus Culicoides take part.

This gives it a stationary character and makes it dependent on the seasons. The disease usually occurs in the summer and spreads most actively on hot days. Most often it is recorded in swampy areas or in areas characterized by big amount annual precipitation and water stagnation.

Animals with poor nutrition and suffering from worms and infections are more susceptible to this disease. Crowded housing and sunlight are also risk factors.
The carrier of viral infection is woodlice

Incubation period and symptoms

Bluetongue is characterized by an incubation period of 6–9 days and can occur in different forms(acute, subacute, chronic, abortive).

In the acute form of the disease, the following symptoms are observed:

• elevated temperature (+41–42 °C), which lasts from 2 to 11 days;
• redness, erosion and ulcers of the oral mucosa;
• increased salivation;
• smell of rot from the mouth;
• purulent nasal discharge;
• swelling of the ears, lips, tongue, jaw, which gradually affects the neck and chest;
• the tongue becomes purple or purple over time bluish shades, may hang down (not always);
• pododermatitis;
• lameness and curvature of the neck;
• in advanced cases, diarrhea with bloody spots, severe weight loss and weakness are observed.

The acute form of the disease usually takes 6–20 days and can be fatal for the animal 2–8 days after the first signs are detected. In subacute or chronic forms of the disease, all of the above signs appear slowly and are not very pronounced.

With this course of the disease, the animal experiences weight loss, poor quality hair, damage to the limbs leading to lameness. Against the background of a sluggish illness, bronchitis, pneumonia and other secondary infectious diseases may appear.

Did you know? A total of 24 bluetongue serogroups have been identified. Vaccines against this disease usually include 4 common strains of the causative virus. The Republic of South Africa has a vaccine containing 14 serotypes of this disease.

The subacute form can last about 30–40 days, while the chronic form lasts for more than a year. The animal with this course of the disease gradually recovers, but death not uncommon, especially in places where bluetongue first appeared.
The abortive form is characterized slightly elevated temperature, minor damage to the mucous membranes, although sometimes necrotic changes can be observed in the oral cavity. Cows experience a depressed state and a drop in milk production.

Usually such signs can be seen if vaccination has been carried out, and the animal’s condition is generally quite satisfactory. Pregnant cows may miscarry or give birth to inferior offspring. Infection is most dangerous for the embryo in the first three months of pregnancy.

Laboratory diagnostics

Since clinical signs of bluetongue are not always evident, laboratory blood tests should be carried out on livestock imported into the farm. This is very important, since in areas where this disease has never been observed, the death of the herd can be about 90% of the entire population.

The causative virus is isolated using serological methods. Most often in Lately For diagnosis, an enzyme-linked immunosorbent assay is used, which accurately detects antibodies to bluetongue.

An animal that has already recovered retains such antibodies for a long time, so this study will not show full picture in places of outbreak of disease epidemics. But it is quite suitable for identifying disadvantaged cows for import into the country or into farms.

For diagnostic purposes, polymerase assay can be used chain reaction, allowing you to identify the serogroup and give the most accurate results.

Pathological changes

With bluetongue in cattle, the following pathological changes are observed:

• severe exhaustion of the whole body;
• poor circulation, which causes swelling in the lower body;
• inflammation of the mucous membranes, which have a bluish tint;
• enlargement and cyanosis of the tongue, which often falls out;
• gums and internal cavities the cheeks are affected by erosion, as well as ulcers;
• the muscles of the skeletal part have multiple foci of tissue death;
• the heart muscle is enlarged and has a loose structure;
• changes in the structure of internal organs;
• dropsy is often detected;
• dystrophic changes in the vascular endothelium, gastrointestinal mucosa and skeletal muscles.

Is it possible to cure

Unfortunately, there is no effective treatment for bluetongue in cattle. this moment No. Treatment is more related to preventive measures. An important point is vaccination. Sick animals are sent for slaughter.

Immunity

An animal that has had bluetongue develops lifelong immunity to this serogroup of the virus. Corresponding antibodies appear in the blood, which can be transmitted to young animals when fed with colostrum. To develop immunity against this disease, a vaccine containing several strains is used.

It is administered to animals under the skin in a volume of 1–2 ml. Immunity develops within 10 days and lasts for more than a year. During the vaccination period, cattle should be protected from active sun. Animals are vaccinated from three months of age.

Important! It is recommended to feed calves and lambscolostrum from a vaccinated mother, notartificial substitutes, since in this case they develop immunity to bluetongue, which lasts for 3–4 months.

Rules for the prevention and control of bluetongue

It is better to prevent such a disease than to treat it. The main prevention against it is, as mentioned above, timely vaccination against the disease.

To prevent the spread of infection, you must adhere to the following recommendations:

• use insecticides and repellents;
• do not walk the herd in swampy areas;
• keep livestock in specialized barns all year round;
• when purchasing new livestock, observe quarantine for a certain period of time;
• carry out serological diagnostics with a time interval of 20 days;
• control the quality of purchased sperm for fertilization;
• do not keep cattle and sheep in the same breeding premises;
• do regular preventive vaccinations, especially 30 days before the appearance of blood-sucking pests (midges, mosquitoes, ticks and others);
• carry out regular general examination, take tests (blood) for timely detection diseases;
• observe hygiene rules and carry out constant disinfection.

If the disease is discovered and tests show positive result, then the entire farm goes into quarantine, and the area within a radius of 150 km is considered unfavorable. This occurs due to the transmission of infection by mosquitoes, flies and other insects.

In order to significantly increase the efficiency of the agro-industrial complex in livestock farming, they import a large number of breeding highly productive cattle from abroad.

Due to the increase in imports of cattle (cattle) to Russia, the risk of bluetongue in Russian Federation.

According to the Information and Analytical Center of Rosselkhoznadzor in Smolensk region A bovine bluetongue virus of an unknown serotype has been identified. The virus was initially detected in cattle imported from Germany. To conduct additional laboratory tests and clarify its origin, samples were taken from cattle imported from Germany at the same time (July - September 2011) to other constituent entities of the Russian Federation, as well as from Russian cattle kept in a 5-kilometer zone around a farm in the Smolensk region, where this cattle was imported from Germany. “Currently, evidence has been received that in the 5-kilometer zone around this farm there are individuals of Russian cattle that are also infected with the same bluetongue virus.”

Bluetongue (“blue tongue”, bluetongue of sheep) is a zooanthroponotic natural focal disease. Under natural conditions, sheep, cattle, deer, camels, buffalo, goats and some other species of wild ruminants are susceptible to infection with the virus.

The first report of a disease in sheep with symptoms of bluetongue was received from South Africa in 1876. Over 135 years, the disease has spread globally, periodically manifesting itself in the form of mass epizootics among susceptible animals Analysis of the epizootic situation for bluetongue in the world last years indicates that the area of ​​infection is constantly expanding. According to the OIE, by 1937 the disease was registered in 13 countries in Africa, and 10 years later - in more than 80 countries in the Western and Eastern Hemispheres. In recent years, the disease has acquired new proportions and is registered in the countries of America, Africa, Asia, and Europe. In August 2006, the disease spread to the countries of Central and Western Europe: Belgium, Germany, the Netherlands, as well as Poland, where the pathogen was introduced with imported livestock.

Modern epizootological features of bluetongue in Europe are that several antigenic types of the virus can circulate simultaneously in one unfavorable area. Infection can occur simultaneously among cattle and sheep on mixed farms. Currently, 24 of its serotypes are known.

An important epizootological feature of bluetongue, which significantly complicates the fight against the disease, is the ability of the virus to form natural foci even if it is introduced once into a certain territory.

Bluetongue is a viral vector-borne disease of ruminants, characterized by feverish state, inflammatory-necrotic lesions of the oral cavity, digestive tract, corolla epithelium and base of the skin of the hooves.

The bluetongue pathogen is transmitted by several species of midges, mosquitoes, ticks and sheep bloodsuckers.

Bluetongue, or “blue tongue,” is not dangerous to humans, but among animals it can cause an epizootic and mass mortality. The mortality rate for this disease can reach 90-100%.

Economic damage from bluetongue in primary focus constitutes direct losses (death and forced slaughter of animals) and the costs of carrying out proto-epizootic measures, in stationary ones - direct losses, decreased productivity of domestic ruminants, disruption of reproduction, as well as restrictions on the export of agricultural products, in particular on trade in livestock, meat, wool and others products of animal origin.

The diagnosis of bluetongue is made on the basis of epizootological, clinical and pathological examination data, as well as the results of laboratory tests - isolation of the virus from the organs and tissues of sick animals, or detection of virus-specific antibodies in the blood serum of sick animals.

To reduce the risk of introduction and eliminate the possibility of the spread of bluetongue on the territory of the Russian Federation, it is necessary: ​​do not import livestock from regions unaffected by bluetongue: conduct a serological examination for bluetongue of all livestock that is imported from countries bordering unaffected and suspected of being unaffected by bluetongue.

Bluetongue – viral disease ruminants, characterized by inflammatory-necrotic lesions of the oral mucosa, especially the tongue, gastrointestinal tract and base of the skin of the hooves, as well as dystrophy and changes in skeletal muscles.

Rosselkhoznadzor detected the bluetongue virus in Russian cattle in a five-kilometer zone around a farm in the Smolensk region, where earlier this year the same virus was detected in imported cattle from Germany, according to the agency’s statement.

Bluetongue (bluetongue, bluetongue) is a viral transmissible disease of ruminants, characterized by inflammatory-necrotic lesions of the mucous membrane of the oral cavity, especially the tongue, gastrointestinal tract, corolla epithelium and base of the skin of the hooves. , as well as dystrophy, changes in skeletal muscles.

Bluetongue was first recorded in South Africa in 1876, and at the beginning of the twentieth century, this problem was considered relevant only for the countries of the African continent.

However, the disease has now been reported on all continents.

Some of the latest reports of bluetongue outbreaks in sheep and cattle come from the Netherlands, Belgium and Germany.

The causative agent of the disease is an RNA virus of the Orbivirus genus of the Reoviridae family.

Sheep, especially lambs, are most susceptible to bluetongue, and to a lesser extent, cattle and goats. Wild ruminants also get sick.

Source of infectious agent– sick animals. Reservoirs of the virus in nature have not been identified. The disease manifests itself in the form of sporadic (isolated) cases and in the form of epizootics (widespread distribution) involving a significant number of susceptible animals.

Bluetongue virus is transmitted by biting midges of the genus Culicoides, which determines the seasonal and stationary nature of the disease. It appears in early summer, reaches a peak incidence in the hot rainy months and disappears with the onset of frost.

The disease is recorded in swampy, low-lying areas, in areas with abundant annual rainfall.

The course of the disease is negatively affected by inadequate feeding, overcrowding of animals, chronic infections, helminthiases, solar radiation.

Incubation period of the disease– 6-9 days. There are acute, subacute, chronic and abortive course of the disease.

In acute cases, the main symptom is a sudden or gradual increase in temperature to 41-42°C, accompanied by depression. The duration of the temperature reaction is from 2-3 to 11 days.

After 1-2 days, hyperemia appears (overflow of blood vessels circulatory system) mucous membranes of the oral and nasal cavities, salivation, serous or purulent discharge from the nose; swelling develops in the head (ears, lips, tongue), intermaxillary space, spreading to the neck and chest, hemorrhages, bleeding erosions, ulcers on the oral mucosa and due to tissue necrosis appear putrid smell from mouth.

A swollen and inflamed tongue becomes purple or dirty blue in color and hangs out of the mouth (this symptom is very rare).

Pododermatitis develops (inflammation of the base of the skin of the hoof), lameness, neck curvature often appears, and in severe cases, diarrhea mixed with blood, severe exhaustion and weakness.

In acute cases, the disease lasts from 6 to 20 days. Death may occur 2-8 days after the first symptoms of the disease appear.

In subacute and chronic course all symptoms develop slowly and are less pronounced.

The animals are characterized by emaciation, dryness and hair loss, damage to the limbs, and lameness.

Collapse of the horny shoe and bronchopneumonia caused by secondary infection and abortions in pregnant ewes are sometimes noted.

The duration of the disease in the subacute course is 30-40 days, in the chronic course - up to a year. Animals recover slowly. Sometimes after apparent recovery, death occurs.

The abortive course is characterized by a slight increase in body temperature, rapidly passing hyperemia of the mucous membranes of the oral cavity, and slight depression.

This course of the disease is observed in sheep of more resistant breeds, in cattle and goats after vaccination.

In cattle, the disease is sometimes accompanied by necrosis of the oral mucosa and a decrease in milk yield with satisfactory general condition body.

Animals that have recovered from the disease acquire lifelong immunity to the type of virus that caused the disease. Reinfection with another type of virus is possible during the same season or the following year.

Lambs born from immune ewes acquire passive colostral immunity (transmitted through mother's milk) lasting up to 3 months.

Polyvalent live and inactivated vaccines are used for immunization.

No specific treatment methods have been developed.

Prevention and control measures

In disease-free countries preventive actions are limited to prohibiting the import of susceptible animals from countries affected by bluetongue, and quarantining domestic and wild ruminants at points of entry.

In threatened areas and stationary foci of the disease, systematic control of vectors is carried out, grazing is prohibited in the evening; during the period of mass summer, insects drive animals from swampy pastures to drier, higher-lying ones; carry out annual vaccination animals.

The material was prepared based on information from open sources

Source: https://ria.ru/spraa/20111230/530031392.html

12. Bluetongue of cattle and sheep

Bluetongue of sheep (febriscatarrhalisovium) - infectious disease, manifested by a febrile state, inflammatory-necrotic lesions of the digestive tract, tongue and degenerative changes in skeletal muscles.

Etiology. The causative agent is an RNA genomic virus that belongs to the family Reoviridae, genus Orbivirus. The particle diameter of the purified culture virus is 50-65 nm.

The virion has a single-layer capsid consisting of 32 capsomers. Viral particles contain 80% protein and 20% ribonucleic acid.

The latter is double-stranded, fragmented (consists of 10 fragments), is not infectious and is not sensitive to cRNAase.

Epizootological data. Sheep, especially young ones, are most susceptible to bluetongue. Their sensitivity to the virus depends on the breed. Merino sheep and their crosses are more sensitive, while Karakul and fat-tailed sheep are less sensitive.

In stationary foci of the disease, sheep of imported breeds are more often affected; local ones are more resistant.B laboratory conditions manages to infect newborn mice and hamsters by injecting the virus into the brain.

Icosis cattle are susceptible to the disease, but their disease has no clinical symptoms. However, they can act as a reservoir of the virus during the inter-epizootic period. The disease is characterized by seasonality.

It appears at the beginning of summer, usually with high humidity, and disappears with the onset of cold weather; not registered in winter. The highest incidence of disease in sheep is observed in hot, rainy months.

The disease is recorded in swampy areas, in areas where there is a lot of rainfall. Sheep usually become infected while on pastures at night.

Inadequate feeding, overcrowding in the room, chronic infections, helminthiases, and solar radiation aggravate the course of the disease.

Course and symptoms. The incubation period of the disease is 7-10 days, with experimental infection - 2-18 days.

In sheep, acute, subacute, chronic and abortive forms of the disease are distinguished.

Acute disease is characterized by a sudden or gradual increase in body temperature to 40.5-42°C.

1-2 days after this, hyperemia of the mucous membranes of the oral and nasal cavities, salivation, and discharge of serous or purulent exudate from the nasal cavity, which subsequently dries up as a crust, appear.

Swelling develops in the ears, lips, sometimes tongue, intermaxillary area, spreading to the neck and chest. Lips become painful underlip droops a lot.

On the mucous membrane of the oral cavity, there are hemorrhages, bleeding erosions, ulcers; due to tissue necrosis, a bad odor comes from the mouth.

A swollen and inflamed tongue acquires a purple or dirty blue color and protrudes from the oral cavity. For this reason, the disease was previously called blue tongue. Often, sick animals have a crooked neck, hair loss, and in severe cases, bloody diarrhea appears. Lack of appetite and specific muscle lesions lead to severe exhaustion, weakness, and deep asthenia.

In subacute and chronic courses of the disease, all symptoms develop slowly and are less pronounced. The animals are characterized by emaciation, dryness and hair loss, and damage to the limbs, accompanied by lameness.

Sometimes the collapse of the horny shoe and bronchopneumonia caused by secondary infection are noted. The duration of the disease in the subacute case is 30-40 days, in the chronic case - up to a year. Animals recover slowly.

Sometimes after an apparent recovery, death occurs. The abortive form is manifested by a slight increase in body temperature, quickly passing hyperemia of the mucous membranes of the oral cavity. Other symptoms of the disease do not develop.

This course of the disease is observed in sheep of more resistant breeds, and in cattle and goats after vaccination.

Diagnosis. The diagnosis is made on the basis of epizootological data, clinical signs, pathological changes and laboratory results.

Isolation of the virus (from blood, spleen, lymph nodes) is carried out in cultured kidney cells of lambs or hamsters, in chicken embryos, which are infected intravenously, and also in mice by intracerebral injection.

The biotest will be carried out on two sheep, previously serologically tested for the absence of complement-fixing antibodies to the catarrhal fever virus; They are injected intravenously with 10 ml of the blood of a sick animal, a suspension prepared from the organs of dead sheep, or a virus isolated in cell culture or in chicken embryos. An increase in temperature to 41 ° C and higher on the sixth to eighth day after infection with the subsequent development of clinical signs of the disease is considered characteristic of bluetongue. In all cases, virus isolation is confirmed by serological methods (RDP, ELISA, MFA, RSK, RN, RNGA).

Differential diagnosis. It is necessary to exclude foot and mouth disease, contagious pustular dermatitis (ecthyma), smallpox, vesicular stomatitis, malignant catarrhal fever, necrobacteriosis

Treatment not developed

Prevention and control measures. Sheep that have recovered from the disease acquire lifelong immunity to the type of virus that caused the disease.

Reinfection with another type of virus is possible during the same season or the following year.

For prevention, a cultural vaccine is used, as a result of which the animal is immune for a year.

Lambs born from immune sheep have passive colostral immunity lasting up to three months.

Infectious bluetongue is not registered in the Republic of Belarus. The main attention should be paid to strict control over the import of animals.

Source: https://StudFiles.net/preview/5710032/page:72/

Sheep bluetongue (febris catarrhalis ovium) (“Blue tongue”, bluetongue)

Sheep bluetongue (febris catarrhalis ovium) (“Blue tongue”, bluetongue) is an infectious disease manifested by a febrile state, inflammatory-necrotic lesions of the digestive tract, tongue and degenerative changes in skeletal muscles.

Etiology. The causative agent - an RNA genomic virus - belongs to the family Reoviridae, genus Orbivirus.

The particle diameter of the purified culture virus is 50-65 nm. The virion has a single-layer capsid consisting of 32 capsomeres.

Viral particles contain 80% protein and 20% ribonucleic acid.

The latter is double-stranded, fragmented (consists of 10 fragments), is not infective and is not sensitive to RNase.

Epizootological data. Sheep, especially young ones, are most susceptible to bluetongue. Their sensitivity to the virus depends on the breed.

Merinos and their crosses are more sensitive; Karakul and fat-tailed sheep are less sensitive.

In stationary foci of the disease, sheep of imported breeds are more often affected; locals are more resilient.

In laboratory conditions, it is possible to infect newborn mice and hamsters by injecting the virus into the brain. Cattle and goats are susceptible to the disease, but in them the disease occurs without clinical symptoms.

However, they can act as a reservoir of the virus during the inter-epizootic period. The disease is characterized by seasonality.

It appears in early summer, usually with high humidity, and disappears with the onset of cold weather; not registered in winter. The highest incidence of disease in sheep occurs during the hot, rainy months.

The disease is recorded in swampy areas, in areas where there is a lot of rainfall. Sheep usually become infected while on pasture at night.

Inadequate feeding, overcrowding in the room, chronic infections, helminthiases, and solar radiation aggravate the course of the disease.

Course and symptoms. The incubation period of the disease is 7-10 days, with experimental infection - 2-18 days.

In sheep, acute, subacute, chronic and abortive forms of the disease are distinguished.
The acute course is characterized by a sudden or gradual increase in body temperature to 40.5-42°C.

1-2 days after this, hyperemia of the mucous membranes of the oral and nasal cavities, salivation, and discharge of serous or purulent exudate from the nasal cavity appear, which subsequently dries into a crust.

Swelling develops in the ears, lips, sometimes tongue, and intermaxillary area, spreading to the neck and chest. The lips become painful, the lower lip droops greatly.

On the mucous membrane of the oral cavity, there are hemorrhages, bleeding erosions, ulcers; due to tissue necrosis, a foul odor emanates from the mouth. A swollen and inflamed tongue becomes purple or dirty blue in color and protrudes from the mouth.

For this reason, the disease was previously called blue tongue. Often, sick animals have a crooked neck, hair loss, and in severe cases, bloody diarrhea appears. Lack of appetite and specific muscle lesions lead to severe exhaustion, weakness, and deep asthenia.

In subacute and chronic courses of the disease, all symptoms develop slowly and are less pronounced. The animals are characterized by emaciation, dryness and hair loss, damage to the limbs, accompanied by lameness.

Collapse of the horny shoe and bronchopneumonia caused by secondary infection are sometimes noted. The duration of the disease in the subacute course is 30-40 days, in the chronic course - up to a year. Animals recover slowly.

Sometimes after an apparent recovery, death occurs. The abortive form is manifested by a slight increase in body temperature, quickly passing hyperemia of the mucous membranes of the oral cavity. Other symptoms of the disease do not develop.

This course of the disease is observed in sheep of more resistant breeds, in cattle and goats after vaccination.

Diagnosis. The diagnosis is made on the basis of epidemiological data, clinical signs, pathological changes and laboratory results.

Isolation of the virus (from blood, spleen, lymph nodes) is carried out in cultured kidney cells of lambs or hamsters, in chicken embryos, which are infected intravenously, and also in mice by intracerebral injection.

The bioassay is performed on two sheep, previously serologically tested for the absence of complement-fixing antibodies to the bluetongue virus; they are injected intravenously with 10 ml of the blood of a sick animal, a suspension prepared from the organs of dead sheep, or a virus isolated in cell culture or in chicken embryos. A characteristic of bluetongue in sheep is considered to be an increase in temperature to 41 ° C and higher on the sixth - eighth day after infection with subsequent development of clinical signs of the disease. In all cases, virus isolation is confirmed by serological methods (RDP, ELISA, MFA, RSK, RN, RNGA).

Differential diagnosis. It is necessary to exclude foot and mouth disease, contagious pustular dermatitis (ecthyma), smallpox, vesicular stomatitis, malignant catarrhal fever, necrobacteriosis

Treatment not developed.

Prevention and control measures. Sheep that have recovered from the disease acquire lifelong immunity to the type of virus that caused the disease.

Reinfection with another type of virus is possible during the same season or the following year.

For prevention, a cultural vaccine is used, as a result of which the animal is immune for a year.

Lambs born to immune ewes have passive colostral immunity lasting up to three months.

Infectious bluetongue is not registered in the Republic of Belarus. The main focus should be on strict controls on the import of animals.

Source: http://webmvc.com/bolezn/livestock/infect/cattle/blue.php

Bluetongue bluetongue (or bluetongue) belongs to a group of exotic, especially dangerous diseases of sheep and domestic and wild ruminants, such as cattle. - presentation

1 BLUETHANG

2 Bluetongue (or bluetongue) belongs to a group of exotic, especially dangerous diseases of sheep and domestic and wild ruminants, such as cattle, goats, deer, mouflon, most species of African antelope and various artiodactyls. Infectious bluetongue (Febris catarrhalis infectiosa, bluetongue, blue tongue, BLO) is a viral vector-borne disease of ruminants, characterized by fever, inflammatory and necrotic lesions of the digestive tract, especially the tongue, corolla epithelium and base of the skin of the hooves, as well as degenerative changes in the skeletal muscles. Pregnant animals can have abortions and give birth to malformed offspring. Clinical manifestations of the disease and morphological changes vary depending on the pathogenicity of the strain, individual characteristics and breed of animals, the influence of environmental conditions (meteorological factors, solar radiation, etc.).

3 Historical reference: The disease was first described in sheep in South Africa in 1876, and then in cattle (1933). Taylor discovered its causative agent in 1905.

Currently, the disease is registered in 36 countries in Europe, Asia, Africa, North and Latin America, Australia and Oceania. The largest number of outbreaks was noted in South Africa and Israel. For the first time in

Outbreaks have been reported in India and Malaysia. In Canada, after freedom from BT since 1976, this disease reappeared in 1976 - a worsening of the epizootic situation with bluetongue in the countries of southern and central Europe.

Outbreaks of bluetongue (BTV serotypes 1, 2, 4, 9 and 16) in sheep and cattle have been reported in Italy, Turkey, Greece, and Tunisia. Losses – more than 1.8 million.

livestock 2006 – BTV serotype 8 – Netherlands, Belgium, Germany, France and Luxembourg 2007 – further spread of BTV-8 – UK, Denmark, Luxembourg

4 Geographic distribution map of bluetongue

6 The causative agent is an RNA-containing virus belonging to the genus Orbivirus of the Reoviriday family. The virion size is 68 nm. There are 24 known serovars. The virus is stable in the pH zone 6.5-8.0.

Resistant to ether and sodium deoxycholate, sensitive to acetone. In a sick animal, the virus can be detected in the blood, spleen and other organs.

The virus is cultivated in mice 1-2 days old, chicken embryos and in cultures of lamb kidney cells, BHK-21, where CPD manifests itself.

7 Epizootological data. Under natural conditions, sheep of all breeds are most susceptible to the pathogen, but Merino sheep are more sensitive. Cases of the disease have also been described in cattle, goats, deer, and antelope.

Cattle become ill mostly asymptomatically.

Infectious bluetongue occurs in the form of epizootics with a large coverage of the population (50-60 percent of the herd), characterized by seasonality (warm, wet season) and a more severe course of the disease in animals exposed to solar radiation.

Biological carriers of the virus are various species of midges of the genus Culicoides; sheep bloodsucker Melophagus ovinus (mechanical vector).

The virus persists between epizootic periods, apparently, in the body of many species of wild ruminant cattle, among which long-term circulation of the virus has been established (over three years).

Being the main reservoir of the pathogen, infected cattle ensure the stationarity of epizootic foci of the disease. In insects, transovarial transmission of the pathogen and transmission during metamorphosis have not been established; they apparently do not take part in the preservation of the virus between epizootic periods. In primary epizootic foci, mortality reaches 90 percent, in stationary ones - 30 percent.

9 Pathogenesis The BLO virus acts directly on muscle tissue and internal organs, causing profound changes in blood vessels. As a result, metabolic processes are disrupted. Animals lose a lot of weight. The disease is usually complicated by secondary infection.

The highest concentration of the virus was found between the 5th and 11th days after infection in the spleen, tonsils, regional lymph nodes, and then in the blood (associated with red blood cells). After 6 weeks, the virus disappears from parenchymal organs.

Neutralizing antibodies circulate in the blood simultaneously with the virus, which is in high titer. In pregnant females, the virus penetrates the fetus and reproduces in the vascular endothelium, causing hyperemia, impaired permeability and subsequent inflammation.

As a result, abortion occurs or malformed offspring are born.

11 Course and symptoms of acute subacute abortive incubation period in natural conditions lasts about 7 days, in experiments – 2-18 days. Forms of the disease

12 Acute The acute course is characterized by short-term fever.

Usually the temperature rises to 40.5-42 °C, the mucous membranes of the oral and nasal cavities turn red, salivation is observed, and bloody mucopurulent discharge from the nasal cavity is observed.

Then the epithelium of the mucous membrane is desquamated, the lips, gums and tongue swell, ulcers appear, and stomatitis develops.

In some animals, the tongue turns dark red to purple or violet, which gives the disease its popular name. Nasal discharge becomes purulent, dries around the nostrils, partially closes the nostrils and makes breathing difficult.

The swelling spreads to the muzzle, intermaxillary space, and sometimes to the neck and chest. Pneumonia often develops, diarrhea with blood appears, and skin cracks form. The limbs are affected and lameness develops.

Damage to the oral cavity and gastrointestinal tract leads to exhaustion. After 3-4 weeks, the hair begins to fall out. In severe cases, patients die within 1-6 days from the onset of the disease. Sometimes, after a visible improvement in the condition of patients, a sharp deterioration occurs and the animals die. This happens 3 weeks or more after the first signs of the disease appear.

13 SUBACUTE In the subacute course, severe exhaustion, prolonged weakness, slow recovery, and sometimes curvature of the neck are noted. The limbs are often affected, first there is lameness, then purulent processes occur in the hooves, and collapse of the horny shoe. The illness lasts for days.

14 ABORTIVE The abortive course of the disease is characterized only by fever, superficial inflammation of the oral mucosa. More often observed in cattle. Recovery occurs relatively quickly.

In approximately 5 percent of cattle, anorexia, swelling of the mucous membrane of the eyes, salivation, hyperemia of the mucous membrane of the oral and nasal cavities, and increased body temperature are observed.

Ulcers are found on the nasal planum, lips, gums, limbs, udder and vulva. The tongue becomes very swollen and protrudes from the mouth. Difficulty swallowing is then recorded. Animals die from thirst and pneumonia.

However, more often BLO in cattle causes abortions and the birth of non-viable, malformed offspring.

15 Pathological changes. The corpse is exhausted. The mucous membranes of the oral cavity and tongue are hyperemic, cyanotic, edematous with the presence of numerous hemorrhages. The epithelium is sweetened, erosions, necrosis, and ulcers are observed on the lips, gums, and tongue.

Red gelatinous areas are found under the skin in the neck, shoulder blades and back. Numerous hemorrhages are noted in muscle tissue, small intestine, myocardium, epicardium, and on the mucous membranes of the respiratory tract, bladder and ureters.

16 The stability of the virus in the external environment is quite high. In preserved blood, at room temperature, it is viable for 25 years.

At a temperature of 60 C it dies in 5 minutes. Weak solutions of phenol do not neutralize it. Acids, alkalis, and chlorine-containing preparations inactivate the virus.

17 Diagnosis.

The disease is established on the basis of epizootic data (seasonality, connection with insect vectors, predominant damage to sheep, occurs in the form of epizootics), clinical signs (fever, damage to the mucous membrane of the oral and nasal cavities, swelling of the head, lameness, hair loss), pathological changes ( necrosis of the mucous membranes, erosions and ulcers in the mouth and tongue, hemorrhage in muscle tissue, intestines), as well as according to the results of laboratory tests - detection of the virus and detection of antibodies in recovered animals. The virus is isolated by infecting mice (intracerebrally), chicken embryos (intravenously), and cell cultures. To clarify the diagnosis, they resort to a bioassay, infecting a healthy sheep intravenously with blood that is suspicious for the disease of the animal. In all cases, virus isolation is confirmed by serological methods. Diffusion precipitation in agar gel, RIF, RSC, RDP are group specific and allow the detection of antibodies to any type of virus; antibodies to the homologous type are detected in the RN and RPGA. An enzyme immunoassay method has been developed for the detection of antigen and antibodies. Bluetongue of sheep should be suspected when fever, inflammatory lesions of the oral cavity and profuse salivation are detected in animals, taking into account the seasonal occurrence of the disease during the period of mass attacks of blood-sucking dipterous insects.

18 Differential diagnosis.

Infectious bluetongue must be distinguished from foot-and-mouth disease (high contagiousness, characteristic foot-and-mouth lesions of the oral cavity, udder, limbs, results of virological studies), contagious ecthyma of sheep (contagiousness, pustular lesions of the mucous membranes and skin, microscopy of smears from pathological material, bioassay on lambs and rabbits), malignant catarrhal fever (sheep rarely get sick, the disease is mostly sporadic, damage to the eyes and upper respiratory tract is typical), necrobacteriosis (in addition to sheep, horses, pigs and other animals get sick, chronic course, excretion of the pathogen), Ibaraki disease (cattle get sick livestock, results of virological and serological studies), epizootic hemorrhagic disease of deer (virological and serological studies).

19 Immunity. Sheep that have recovered from the disease acquire long-term and intense immunity only against the type of virus that caused the disease; against the heterologous type, the protection is weak. Complement-fixing, precipitating and virus-neutralizing antibodies accumulate in the blood.

Lambs born from immune sheep remain immune to this disease for 3 months. A vaccine against BLO has been proposed from a virus strain modified by successive passages on sheep, as well as from virus strains passaged on chicken embryos.

Immunity in vaccinated sheep appears after 10 days and lasts for at least a year. Abroad and here (V.A. Sergeev et al., 1980) inactivated vaccines have been proposed that are harmless to pregnant ewes and non-reversible.

Strong immunity and specific antibodies in high titer remain for at least a year.

20 Prevention and control measures. Infectious catarrhal fever is not registered with us. The main attention is paid to preventing its introduction into our country with imported domestic (sheep, goats, cattle) and wild ruminants.

Preventive quarantine is mandatory, with virological and serological studies carried out if necessary.

In areas that are permanently unaffected by infectious bluetongue in sheep, it is necessary to vaccinate susceptible livestock at least a month before the onset of the disease season.

When a disease appears, vaccination should also be carried out using vaccines against the type of pathogen that caused the disease in a given outbreak. At the same time, measures are taken to protect animals from insect attacks. Restrictive measures are also being introduced.

21 Treatment. No treatments have been developed for animals.

23 conjunctivitis

24 ulceration of the oral mucosa

28 Swelling of the facial part of the head

29 Swelling and ulceration of the mucous membrane of the tongue

30 Damage to the udder teats in cattle clotting

31 Paralysis and prolapse of tongue

32 Desquamation of the epithelium of the nasal planum in cattle patients

33 Hemorrhagic lesion of the muzzle of cattle

34 Conclusion.

To minimize the risk of introduction and eliminate the possibility of the spread of bluetongue on the territory of the Russian Federation, it is necessary: ​​not to import livestock from regions unfavorable for bluetongue; Conduct serological testing for bluetongue of all livestock imported from countries bordering and suspected of being bluetongue-affected. If there is a suspicion of bluetongue, immediately inform the state veterinary service of the region and send samples of pathological material for testing for bluetongue; When bluetongue appears, act in accordance with the “Temporary instructions on measures to combat bluetongue in sheep”, approved by the Main Directorate of Internal Affairs of the USSR Ministry of Agriculture on March 27, 1974.

35 List of used literature Murueva G.B. “Natural focality of cptral fever in sheep.” Sheep, goats, wool industry with V.I. Balysheva, V.V. Slivko, V.I. Zhesterev - “Cultivation of bluetongue virus in animal cell cultures” with A.A. Strizhakov.

“Creation of means for epitome analysis of structural and non-structural polypeptides of the bluetongue virus.” Bulletin of the Russian Academy of Agricultural Sciences Strizhakov A.A. "TF inhibition ELISA method for serological monitoring of Bluetongue." Veterinary medicine with Shoopala Johannes.

“Features of the manifestation of infectious bluetongue in sheep in Namibia.” Veterinary science with Zharov A.V., Gulyukin M.I., Barabanov I.I.

“Pathoanatomical and histological studies in the monitoring system pathological processes in the body of farm animals, birds and fish.” Veterinary consultant, 10. - Strizhakov A.A.

“Sandwich method of enzyme-linked immunosorbent assay based on monoclonal antibodies for the detection of bluetongue virus antigens.” Agricultural biology with Kolomytsev A.A. “Bluetongue of sheep: problems of epizootic monitoring.” Veterinary consultant pp. 4-7.

36 Thank you for your attention!

Source: http://www.myshared.ru/slide/1247420

Bluetongue (bluetongue) - causes, symptoms and treatment

Bluetongue of sheep, which has the rather exotic name “blue tongue” or “bluetongue”, refers to viral diseases, characterized by a high percentage of livestock damage, causes significant damage to sheep farming.

The disease has been known since the end of the last century. The disease was first recorded and described in small cattle in Southern Africa. The pathogen was discovered in 1905.

In the 30s of the last century, the connection between bluetongue and a similar disease in cattle was proven.

Almost until the mid-twentieth century, the disease was considered exclusively a problem of the continental countries where it was first discovered.

Recently, mainly due to the import of animals and sheep products, it has become widespread. It is registered in many countries; in the Russian Federation it is classified as a quarantine disease.

Information about outbreaks of the disease periodically comes from France, Germany, the Netherlands, Belgium and other European countries.

When information about an epizootic is received, the import of animals and related livestock products from the territory of disadvantaged countries is limited.

The frequent asymptomatic course of the disease gives scientists reason to assume that bluetongue is more widespread than is commonly believed.

Conducted research to identify specific antibodies in animals in many countries confirms this guess.

In particular, serological evidence of the circulation of the pathogen was obtained in Canada, Mexico, Brazil, Iran and a number of other countries previously considered free from bluetongue.

Pathogen and epidemiological data

The cause of the disease in sheep is a small RNA-containing microorganism belonging to the genus Orbivirus of the reovirus family.

They are characterized by a hexagonal shape and the presence of a loose, unstable outer shell. The accumulation of the pathogenic agent occurs in the blood and internal organs of the infected animal.

Transplacental transmission of the virus has been noted.

In the laboratory, the virus replicates in chicken embryos, some cell cultures. Artificial infection of mice and hamsters is possible. Sheep, goats, and less so cattle are susceptible to natural infection. Among wild animals, the disease is observed in:

• moose;
• deer;
• wild sheep;
• antelope

The main route of transmission of the virus is transmissible. The carriers of the virus are small blood-sucking families of biting midges, which belong to the components of midges.

It is this fact that determines the natural focal nature of the disease, as well as the presence necessary conditions for an outbreak to occur. These include high temperature environment and high humidity.

It is under these conditions that a massive outbreak of insects and infection of susceptible animals occurs.

In the cold season, in the absence of natural carriers, the disease does not occur.

However, in 1965 the possibility of infection of sheep was proven large doses virus through the nutritional route. However, if such cases arise naturally, then they are isolated in nature and do not take the form of an epizootic.

Sheep of all ages and breeds, regardless of gender, are susceptible to the bluetongue virus.

A proven fact is the increased infectivity of merino breeds and the greater susceptibility of young animals.

In adult animals, the disease often takes atypical forms, which do not raise suspicions about the development of this particular disease.

In cattle, the disease is mild, most often hidden. According to US veterinarians, the disease is clinically manifested in less than 5% of infected cows.

The latent course of the disease in cattle leads to the emergence of a focus of the disease and its rapid expansion among sheep located within a given area. In addition to large ruminants, wild animals are the natural reservoir of the pathogen.

The absence of a clinic and the long (about 3 years) existence of the pathogen in their blood helps the microorganism survive the inter-epizootic interval.

Symptoms

The incubation period for natural infection lasts about a week. With artificial infection it is 2-18 days.

After the end of the incubation period, clinical signs of the disease appear.

Depending on the number of viruses that have entered the sheep’s blood and the state of its immunity, the disease can develop in one of the possible forms:

• acute;
• subacute;
• chronic;
• abortive.

The acute form is the most indicative in terms of the manifestation of clinical signs. First of all, it is noted sharp increase temperatures up to 41-42°C (at a norm of 38.5-40°C in adult animals).

It develops within 1-2 days catarrh mucous membranes of the oral and nasal cavities, characterized by hyperemia of the mucous membranes, salivation, nasal discharge, difficulty breathing, accompanied by snoring and snorting.

Following this, swelling of the lips, tongue, and ear area develops. Hemorrhages and ulcerations occur in the oral cavity and on the lips.

The addition of secondary microflora leads to the development purulent inflammation, noticeable unpleasant smell from the animal's mouth.

The lips droop, a swollen tongue of a purplish-bluish color protrudes from the mouth.

There are disorders of the digestive tract, sudden weight loss, and sometimes hair loss.

Death occurs against a background of general weakness and exhaustion.

Subacute and chronic forms develop in a similar way, with less severity of symptoms and a slower development. The abortive form is characterized by an asymptomatic course, a satisfactory general condition and often ends in self-healing.

Those who have recovered remain virus carriers for some time; subsequently, the pathogen is eliminated from the blood, and stable immunity to the type of pathogen with which the animal was infected develops.

Treatment and prevention

Specific treatment for bluetongue has not been developed. Sick sheep are sent to slaughter.

In case of high productive or breeding value and the feasibility of preserving animals with clinical signs placed in a separate room, improve living and feeding conditions.

Apply symptomatic therapy aimed at improving general condition. Grazing of sick animals is prohibited, since ultraviolet irradiation provokes aggravation of the pathological process.

Certain therapeutic activity bluetongue is treated with drugs containing arsenic compounds.

The basis of the fight against the disease is strict adherence to quarantine measures when importing animals. New arrivals are quarantined for 30 days. The import of livestock and individuals from disadvantaged regions is prohibited.

If an outbreak occurs, grazing in evening time(during the mass summer of midges).

Measures are being taken to drain wetlands in the immediate vicinity of grazing areas, as well as to combat insects using insecticides and protect small livestock using repellents.

Susceptible livestock are subjected to active immunization using live and inactivated vaccines against bluetongue.

Vaccination is carried out once a year before pasture.

Lambs up to three months of age, obtained from recovered and immunized mothers, have colostral immunity.

Rosselkhoznadzor detected the bluetongue virus in Russian cattle in a five-kilometer zone around a farm in the Smolensk region, where earlier this year the same virus was detected in imported cattle from Germany, according to the agency’s statement.

Bluetongue (bluetongue, blue tongue) is a viral transmissible disease of ruminants, characterized by inflammatory and necrotic lesions of the mucous membrane of the oral cavity, especially the tongue, gastrointestinal tract, corolla epithelium and base of the skin of the hooves. , as well as dystrophy, changes in skeletal muscles.

Bluetongue was first recorded in South Africa in 1876, and at the beginning of the twentieth century, this problem was considered relevant only for the countries of the African continent. However, the disease has now been reported on all continents. Some of the latest reports of bluetongue outbreaks in sheep and cattle come from the Netherlands, Belgium and Germany.

The causative agent of the disease is an RNA virus of the Orbivirus genus of the Reoviridae family.

Sheep, especially lambs, are most susceptible to bluetongue, and to a lesser extent, cattle and goats. Wild ruminants also get sick.

Source of infectious agent- sick animals. Reservoirs of the virus in nature have not been identified. The disease manifests itself in the form of sporadic (isolated) cases and in the form of epizootics (widespread distribution) involving a significant number of susceptible animals.

Bluetongue virus is transmitted by biting midges of the genus Culicoides, which determines the seasonal and stationary nature of the disease. It appears in early summer, reaches a peak incidence in the hot rainy months and disappears with the onset of frost. The disease is recorded in swampy, low-lying areas, in areas with abundant annual rainfall. The course of the disease is negatively affected by inadequate feeding, overcrowding of animals, chronic infections, helminthiasis, and solar radiation.

Incubation period of the disease- 6-9 days. There are acute, subacute, chronic and abortive course of the disease. In acute cases, the main symptom is a sudden or gradual increase in temperature to 41-42°C, accompanied by depression. The duration of the temperature reaction is from 2-3 to 11 days. After 1-2 days, hyperemia (overflow of blood in the vessels of the circulatory system) of the mucous membranes of the oral and nasal cavities, salivation, serous or purulent discharge from the nose appears; swelling develops in the head (ears, lips, tongue), intermaxillary space, spreading to the neck and chest, hemorrhages, bleeding erosions, ulcers on the oral mucosa and, due to tissue necrosis, a putrid odor from the mouth appear.

A swollen and inflamed tongue becomes purple or dirty blue in color and hangs out of the mouth (this symptom is very rare). Pododermatitis develops (inflammation of the base of the skin of the hoof), lameness, neck curvature often appears, and in severe cases, diarrhea mixed with blood, severe exhaustion and weakness.

In acute cases, the disease lasts from 6 to 20 days. Death may occur 2-8 days after the first symptoms of the disease appear.

In subacute and chronic cases, all symptoms develop slowly and are less pronounced. The animals are characterized by emaciation, dryness and hair loss, damage to the limbs, and lameness. Collapse of the horny shoe and bronchopneumonia caused by secondary infection and abortions in pregnant ewes are sometimes noted.

The duration of the disease in the subacute course is 30-40 days, in the chronic course - up to a year. Animals recover slowly. Sometimes after apparent recovery, death occurs.

The abortive course is characterized by a slight increase in body temperature, rapidly passing hyperemia of the mucous membranes of the oral cavity, and slight depression. This course of the disease is observed in sheep of more resistant breeds, in cattle and goats after vaccination. In cattle, the disease is sometimes accompanied by necrosis of the oral mucosa and a decrease in milk yield with a satisfactory general condition of the body.

Animals that have recovered from the disease acquire lifelong immunity to the type of virus that caused the disease. Reinfection with another type of virus is possible during the same season or the following year. Lambs born from immune ewes acquire passive colostral immunity (transmitted through mother's milk) lasting up to 3 months. Polyvalent live and inactivated vaccines are used for immunization.

No specific treatment methods have been developed.

Prevention and control measures

In disease-free countries, preventive measures are limited to prohibiting the import of susceptible animals from countries unaffected by bluetongue, and quarantining domestic and wild ruminants at the points of entry.

In threatened areas and stationary foci of the disease, systematic control of vectors is carried out, grazing is prohibited in the evening; during the period of mass summer, insects drive animals from swampy pastures to drier, higher-lying ones; Animals are vaccinated annually.

The material was prepared based on information from open sources