- viral transmissible disease of ruminants, characterized by fever, inflammatory necrotic lesions of the oral cavity (especially the tongue), gastrointestinal tract, corolla epithelium and the basis of the skin of the hoof, as well as degenerative changes in skeletal muscles.
Causative agentRNA - virus containing the genus Orbivirus is included in this. Reoviridae.
The spectrum of pathogenicity.Sheep are the most sensitive to the KLO virus from domestic animals. It is shown that European breeds are more sensitive than African and Asian, such as Persian black, karakul. Lambs born to unimmunized queens are very sensitive to the virus. Cattle and goats are sensitive to the KLO virus.
Sources of infection and routes of transmission.The KLO virus is able to multiply in mammals (ruminants) and insects. Under natural conditions, vertebrates become infected with bites of blood-sucking insects.
CLO is a seasonal disease, as it is associated with periods of summer biting midges. Usually CLO occurs in spring and early summer, it spreads predominantly in river valleys, lowlands, swampy places, full of biting midges. Grazing sheep in such places, especially in the evening and at night, is fraught with increased danger of infecting CLO. It is established that cattle lamb is the main host of the CLO virus.
Epizootological data. Under natural conditions, sheep of all breeds are most susceptible to the pathogen, but merino are more sensitive. Infectious catarrhal fever occurs in the form of epizootic with a large coverage of the population (50-60% 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 - various types of biting midges of the genus Culicoides, sheep bloodsucker Melophagus ovinus (mechanical carrier). In the interepizoonichesky period, the virus persists, apparently, in the body of many species of wild ruminants and cattle, among which there is a long-term circulation of the virus (over three years). Being the main reservoir of the pathogen, infected cattle provides the stationarity of epizootic foci of the disease.
The incubation period is 6-8 days. After the incubation period, the temperature rises to 40.6 - 42.0 °, fever lasts from 6-8 to 12 days. In 24-36 hours after the first temperature rise, the skin of the muzzle, lips, ears, mucous membranes of the oral and nasal cavities develops, accompanied by the expiration of foamy saliva and peculiar continuous movements of the tongue. Muco-catarrhal effusions appear from the nasal cavity, sometimes with an admixture of blood. The lips and tongue are noticeably swollen, the muzzle is enlarged, it becomes darker in color, point hemorrhages appear on the mucous membranes of the mouth, nose, eyes. In a small percentage of cases, the language becomes red-blue (hence the name of the disease). Hair falls on the muzzle, erosions are formed on the mucous membranes of the mouth and nose, which bleed easily. In more severe cases, the mucous membranes of the cheeks, gums and tongue ulcerate and bleed, saliva mixes with blood and necrotic tissues, takes on an unpleasant odor. Nasal effusions become purulent and dry crusts around the nose, causing anxiety to animals, thirst develops. Because of the pain in the mouth, the feed intake stops, the animal lies on its side. In cases of death, enteritis develops, accompanied by diarrhea. Sometimes at the height of a fever, but more often after a decrease in temperature, on the hind limbs, one can see redness of the corolla of the hoofs, with increased temperature and soreness under pressure. Redness then turns blue with dark red foci, after which the hoof grows incorrectly with waviness. By the number of these wavy lines, you can judge the number of virus types that an animal had had. Soreness leads to lameness, unwillingness to move, connectedness of gait. The back arches, and the sheep often, driven by hunger, move toward the stern on their knees. The inability to take food and muscle damage leads to progressive exhaustion, accompanied by a violation of intestinal activity. In this state, animals can remain up to 10 days and further to death - in prostration and exhaustion. 3-4 weeks after the cessation of fever, hair begins to fall, hanging down in tufts. The duration of the disease is different. Mouth lesions can heal slowly (depending on the secondary microflora). With a mild course of the disease, a short fever and transient hyperemia of the mucous membranes of the mouth are noted. In acute cases, edema of the pharynx and paresis of the esophagus can cause severe aspiration pneumonia, leukopenia in the blood, poikilocytosis, and later anemia. In severe cases, hemoglobin and total nitrogen are reduced. After the 8th day from the moment of infection, a marked increase in γ-globulins and a less pronounced increase in globulins are noted, the levels of α1 and α2-globulins and albumin are lowered.
In subacute course, the described symptoms are less pronounced; changes in the mucous membranes of the head, inflammation of the skin, hooves, exhaustion, loss of hair, can be noted; death can occur only after a year.
In the case of an abortive course (sometimes), which is possible after vaccination, mild fever occurs, mild mucous hyperemia without ulceration, the appetite is preserved.
In cattle, CLO occurs in most cases as a latent infection, especially in enzootic zones. At the initial occurrence of the disease described symptoms resembling foot and mouth disease and CLO in sheep. Recently, there have been reports of abortions and the birth of ugly, dwarf and underdeveloped calves.
Pathological changes.At autopsy, the following changes are found: subcutaneous tissue and muscular connective tissue are swollen, soaked in yellowish liquid. The tissues of the lips, tongue, ears, the pharynx and larynx, the maxillary region, the thorax are also swollen. The edematous fluid sometimes becomes reddish from a mixture of blood or a gelatinous consistency. In the thoracic and abdominal cavities, there may be a collection of edematous fluid in the pericardium.
If the animal fell in the acute period of the disease, then the most pronounced changes are noted in the digestive system: the mucous membrane of the mouth is hyperemic, edematous, cyanotic, covered with different sizes and shapes of hemorrhages. On the lips, tongue, inner surface of the cheeks, ulcerations, sometimes extensive, covered with dirty grayish necrotic masses, through which blood leaks. In the rumen and the mesh, in the rennet, hyperemia and hemorrhages are observed, most pronounced on the papillae and leaflets. The esophagus can be hyperemic, covered with ulcerations and even foci of necrosis. The mucous membrane of the abomasum is diffusely hyperemic, sometimes cyanotic and covered with various forms and hemorrhages. In the intestinal chamber, inflammatory changes range from focal hyperemia to catarrhal process throughout (to the thick section). The nasal cavity is filled with dirty yellow catarrhal contents flowing from the nose. The nasal septum is swollen, filled with blood and ulcerated. The trachea contains a frothy liquid that appears when there is edema or pulmonary hyperemia.
Changes in the vascular system are characterized by hyperemia of all tissues, edema and hemorrhage. There is a small amount of fluid in the heart shirt, as well as hemorrhages under the epicardium and endocardium. In the medial layer at the base of the pulmonary artery in acute cases, as a rule, hemorrhages. Sometimes in the papillary muscle of the left ventricle, foci of necrosis are found, which can spread throughout the heart muscle.
The spleen and lymph nodes are usually only slightly enlarged. The most frequently affected are the pharyngeal, cervical, mediastinal, maxillary, bronchial, mesenteric, pre-lobe, hypoglossal lymph nodes, which in this case are enlarged, reddened and swollen. In the liver - venous congestion and degenerative changes. In the kidneys - hyperemia, edema.
The main changes most consistently occur in the skin and muscles. Sometimes the lesions on the skin of the muzzle and the crown of the hoof are limited only to redness. More often, the reddening on the corolla is replaced by the appearance of point foci, which merge and form vertical reddish stripes in the substance of the horns. These changes are more often observed on the hind limbs.
Changes in the muscles are expressed by edema of the intermuscular connective tissue and fasciae with a reddish gelatinous fluid. The muscles of the hips, shoulder blades, back, sternum are often affected (Moulten, 1961). They reveal small (1-2 mm) hemorrhages, as well as foci of necrosis. Degenerative changes in the muscles are sometimes so deep that the muscles become grayish and become similar to boiled ones.
Diagnostics.The diagnosis of CLO is made on the basis of epizootological, clinical, pathological and morphological data and laboratory results.
The appearance of the disease in the hot rainy period, the simultaneous increase in the number of blood-sucking insects, the nature of the terrain (lowlands, wetlands, river valleys, etc.), the presence of imported stock (from safe zones) of animals are important from epizootological data.
Clinical symptoms include fever, depression, cyanosis of the tongue, lips, gums, swelling of the muzzle, curvature of the neck, and lameness. The degree of their severity can vary within very wide limits.
From pathoanatomical changes deserve attention. exhaustion, swelling of the subcutaneous and intermuscular connective tissue, degenerative changes of skeletal muscles, necrosis of the mucous membranes of the mouth, tongue, lips, etc.
The presence of these signs and the detection by CSC of antibodies in the blood of animals to the KLO virus make it possible to make a preliminary diagnosis for sheep catarrhal fever.
The final diagnosis is based on the results of experimental infection of sheep, isolation and identification of the virus. The virus can be identified:
1) from whole blood obtained during fever,
3) from the lymph nodes (especially the mesenteric, taken in the acute stage of the disease). Material for virus isolation is taken in Edington's preservative fluid. For virus isolation, pathological material is infected with either 6-8 days old chicken embryos, or cell cultures (PU, VNK-21, L, BEP, etc.)> or mouse-suckers (intracerebrally), or sheep (the most sensitive object). As a rule, the virus is released after several blind passages. Even on sheep sometimes it is necessary to spend 2-3 passages.
For differentiation of the isolated virus from other viruses, CSCs are used, and for typification, a neutralization reaction. CSC in CLO is group-specific and can be used to detect antibodies to any strain of CLO virus. RSK is used for serological intelligence of the area for the circulation of the CLO virus in it. The neutralization reaction is used to study the immune status of the animal and for the typing of the isolated virus. Best results are obtained with prolonged (24 h) contact of the virus with serum at a temperature of + 37 °.
A quick result is obtained by using the fluorescent antibody method with a culture of infected cells. Specific luminescence It is detected already in the 1st passage of the virus on a cell culture, when there is no CPD yet. In addition, in the infected cell culture, as early as the 1st passage, specific bodies-inclusions can be detected.
Differential diagnosis.Infectious Bluetongue be distinguished from FMD (high contagiousness characteristic aphthous lesions of the oral cavity udder extremities of virological studies), contagious ecthyma sheep (contagious pustular lesions of mucous membranes and skin, smear microscopy of pathological material bioassay for lambs and rabbits), malignant catarrhal fever (sheep rarely get sick, the disease is mostly sporadic, eye and upper respiratory tract diseases are typical), some robakterioza (except for sheep suffer from horses, pigs and other animals, chronic course, pathogen isolation), Ibaraki disease (cattle are sick, the results of virological and serological studies), epizootic hemorrhagic disease of deer (virological and serological studies).
CLO must be differentiated from the following diseases:
Hydropericarditis. (Extremely dangerous non-contagious disease of sheep caused by Ricketsia ruminantum and transmitted by mites of the Amblioma River. It is characterized by fever and nerve symptoms. It is common in the same areas of Africa as CLO. There are no nerve phenomena in CLO, fever is longer, the course is slower, it is not amenable to antibiotics .
Rift Valley Fever. Sheep mortality is up to 100%, calves - 70-100%, abortions. On necrosis and degeneration in the liver, acidophilic inclusions in the liver cells.
Differentiation from CLO for RA, MFA, RSK, RZGA.
Sheep pox Lesions of the skin and mucous membranes of the mouth,
respiratory tract, gastrointestinal tract. When K. LO - lesions only in (oral and nasal cavities, lack of contagiousness.
Contagious ecthyma of sheep. Formation of papules and vesicles on the lips and nostrils, sometimes around the eyes. They are replaced by pustules and a thick crust, are not accompanied by edema and hyperemia of the mucous membranes, which is characteristic of CLO. Difference from CLO and by epizootology.
Foot and mouth disease. Lesions develop rapidly, cover a large percentage of animals, the disease is highly contagious, and there are aphthae. None of this is at CLO.
"Weeping disease". This disease occurs in calves aged from 1 week to 6 months, is transmitted by ticks, characterized by stomatitis, hyperemia of the mucous membranes and skin with the development of wet eczema. Difterter inflammation often develops in the mouth and throat. The disease is not transmitted with the blood of the sheep is characterized by severe course and mortality.
Vesicular stomatitis. Can be differentiated from CLO by epizootology. Horses get sick too.
Three-day disease of cattle. (Stiffsickness - stiffness). It is manifested by lameness, stiffness of movements, paresis (pass quickly), high fever (passes quickly). There is no hyperemia, sheep is not transmitted (as CLO).
Immunity and prevention.Recovered sheep acquire lifelong immunity to the type of virus that caused the disease. Repeated illness is possible during the same season or next year, but only in the event of infection with another type of virus.
Annual vaccination is recommended, since the post-vaccination immunity is established a year later, but how long it lasts is not known. To avoid post-vaccination complications, mass vaccination is recommended after shearing sheep.
Avoid vaccination of the swine females, since the attenuated strains cause abortions and the birth of ugly lambs. Vaccination of manufacturing rams can cause their temporary sterility, therefore, rams are vaccinated after the season of mating. Lambs born to immune queen cells remain immune until 3-6 months old and during this period do not respond to vaccine immunization.
For immunization use: vaccine against bluetongue (catarrhal fever of sheep) culture inactivated (VNIIViM), mono - and bivalent inactivated adsorbed vaccines, etc.
Treatment.Currently there are no drugs specifically acting on the CLO virus in vivo. The success of the use of antibiotics and sulfonamides is explained by their effect on the secondary infection, especially with the development of bronchopneumonia.
Careful care of sick animals is the most important measure. Sick animals must be placed in rooms protected from direct sunlight. A small amount of tender green food at the time when the lesions on the mucous membrane of the mouth cause pain when taking food, improves the condition of animals. Superficial lesions moistened with disinfectants, make alcohol lotions. During the recovery period, it is most important to maintain and, if necessary, stimulate the activity of the scar. Careful and good feeding and care helps to reduce the recovery period and restore normal condition.
Control measures.Infectious catarrhal fever is not registered with us. The main attention is paid to preventing its entry into our country with imported domestic (sheep, goats, cattle) and wild ruminants. Preventive quarantine is mandatory, and virological and serological studies are carried out if necessary.
In a locally unfavorable area of infectious catarrhal fever, it is necessary to vaccinate susceptible livestock no less than a month before the onset of the disease season.
При появлении болезни также следует проводить вакцинацию с использованием вакцин против того типа возбудителя, который вызвал заболевание в данном очаге. Одновременно применяют меры по предохранению животных от нападения насекомых. Вводят также ограничительные меры.
В настоящее время нет принятой в международном масштабе инструкции по борьбе с КЛО. The International Epizootic Bureau has developed only the following basic principles for preventing the introduction of CLO in prosperous countries.
1. Prohibition of the importation of sheep, goats, cattle and wild ruminants into the safe zones of CLO, as well as their sperm, blood and serum from countries (or foci) unfavorable according to CLO.
2. Destruction of KLO carriers on all vehicles (ships, airplanes, cars, trains, etc.) arriving from countries (outbreaks) unfavorable for KLO.
3. When importing susceptible animals from countries considered to be safe for CLO, it is necessary to require the presentation of an international veterinary sanitary certificate certifying that imported animals from the safe CLO zone (country), that they have been quarantined for 40 days and subjected to diagnostic studies.
4. Animals imported from other countries must last for 30 days. In the period of quarantine, conduct:
a) daily clinical examination and thermometry,
b) a study in the RAC serum for the presence of antibodies to the CLO virus,
c) pathological material (blood, affected muscles) for virological and pathological-morphological studies is taken from animals suspected of the disease.
In the event of the discovery of diseased animals or animals with a virus carrier, the entire group of imported animals is killed using meat for sausage cans.
5. When a CLO is established in a farm, the settlement with allocated grazing is declared unfavorable, it is quarantined and the following measures are taken:
a) It is prohibited to export domestic and wild ruminants to other farms,
b) It is prohibited to export semen, blood and serum from domestic and wild ruminants,
i) All transport outside the disadvantaged area must be treated with insecticides,
d) For unsuccessful flocks of sheep establish permanent veterinary surveillance. Sick sheep are isolated, subjected to symptomatic treatment and treated with insecticides.
e) The premises, pens, where the unfavorable flocks were kept, as well as the places of slaughter must be disinfected: with 2-3% sodium hydroxide solution, sodium hypochlorite solution, bleach or 2% formaldehyde solution.
f) During the period of insect activity, it is necessary for sheep to be kept on elevated areas of pastures, and to drive them to the premises at night and free them from "insects."
6. Slaughter and use for meat of sheep suffering from CLO is allowed within the limits of unfavorable points with the permission of veterinary authorities.
In the presence of degenerative changes in the musculature, gelatinous infiltrated connective tissue in the intermuscular spaces, reddening of the internal and subrenal fat, hemorrhages in the subcutaneous tissue of the carcass are sent entirely for technical disposal.
7. Skins obtained from the slaughter of sick animals or removed from corpses are neutralized by rubbing with a curing mixture containing 83% sodium chloride, 7.5% ammonium chloride and 2% soda ash, followed by storing and curing for at least 10 days.
8. In unfavorable points (outbreak), all the livestock of sheep are subjected to preventive vaccination:
adult sheep - 3-4 weeks before the start of mating,
sheep-producers - after mating,
lambs - on reaching 5 - 6 months of age.
Vaccinated animals within 10 - 14 days after vaccination contain in cool, protected from the sun, insects and ticks places.
9. Sale, exchange, transfer to other households of domestic and wild ruminants from disadvantaged areas are prohibited.
Symptoms and diagnosis
The incubation period for cattle bluetongue is 7-10 days. However, recently there has been a tendency to an increase in the incubation period, in some cases it can be 30-40 days. After this period, the animal can observe the following signs of the disease:
- Temperature increase to 42 ° С. Characteristic for the first days of illness.
- Swelling of the mucous membranes, their redness, up to purple and dirty blue. The tongue protrudes from the mouth due to swelling.
- The appearance of a putrid odor in the mouth and frothy saliva. Discharge of pus from the nose.
- When viewed in the oral cavity marked ulcerative foci.
- The appearance of hemorrhage on the conjunctiva.
For the diagnosis of the disease using the available clinical signs, pathological changes, as well as special laboratory tests. It is possible to isolate a virus-pathogen using serological methods: enzyme immunoassay and neutralization reactions. When making a diagnosis, it is important to exclude diseases such as foot and mouth disease, smallpox, vesicular stomatitis, contagious pustular dermatitis, a malignant form of catarrhal fever.
The tongue protrudes from the mouth due to puffiness.
The main measure of prevention of bluetongue in cattle is the use of culture vaccine, which gives stable immunity for 12 months. The ill animal has lifelong immunity and does not get sick again, however, it is possible that the disease will recur with another type of virus. Lambs born to cattle with immunity from bluetongue, have passive colostral immunity for 3 months after birth.
Blutang cattle has a high lethality. In stationary foci, it can be 10–30%, while in new territories, the loss of livestock from virus damage can reach 90%. That is why it is important to observe preventive measures and systematically control the disease vectors, which are the biting midges of Culicoides.
Pathogen, sources and routes of infection
Blutang is caused by an RNA-containing virus from the Orbivirus genus (family Reoviridae). The disease is both single and widespread. Its source is sick animals. Biting midges of the genus Culicoides are involved in the transmission of this viral infection.
This gives it a stationary nature and makes it dependent on the seasons. The disease usually occurs in the summer and is most actively spread on hot days. Most often it is recorded in swampy areas or in areas characterized by a large amount of annual precipitation and water stagnation.
This disease is more susceptible to malnourished animals suffering from worms and infections. Risk factors for occurrence are also crowded animals and sunlight. Carrier of viral infection - woodlouse
Incubation period and signs
Blutang is characterized by an incubation period of 6–9 days and can occur in various forms (acute, subacute, chronic, abortive).
In the acute form of the disease, the following symptoms are observed:
- increased temperature (+ 41–42 ° C), which lasts from 2 to 11 days,
- redness, erosion and ulcers of the mucous membranes of the mouth,
- increased salivation,
- the smell of rot from the mouth,
- purulent nasal discharge
- puffiness of the ears, lips, tongue, jaw, which gradually engulfs the neck and chest,
- over time, the tongue becomes crimson or bluish shades, it may hang (not always),
- limp and curvature of the neck,
- in advanced cases, there are diarrhea with bloody patches, large weight loss and weakness.
The acute form of the disease usually takes 6–20 days and can be fatal for an animal at 2–8 days after the first signs are detected. In subacute or chronic forms of the disease, all of the above symptoms appear slowly and are not very pronounced. With this course of the disease, the animal has a loss of weight, a poor quality of coat, and a lesion on the limbs leading to lameness. On the background of a sluggish disease, bronchitis, pneumonia and other secondary infectious diseases may appear.
The subacute form can last about 30–40 days, and the chronic bothers for more than a year. An animal with this course of the disease gradually recovers, but death is not uncommon, especially in places where bluetang appeared for the first time. The abortive form is characterized by a slightly increased temperature, a slight lesion of the mucous membranes, although necrotic changes can sometimes be observed in the oral cavity. Cows have a depressed state and a drop in milk production.
Usually such signs can be seen if vaccination has been carried out, and the condition of the animal as a whole is quite satisfactory. Pregnant cows can have a miscarriage or give birth to inferior offspring. The most dangerous for the embryo infection in the first three months of pregnancy.
Since the clinical signs of bluetongue do not always appear, laboratory blood tests should be performed for livestock brought into the farm. This is very important, since for areas where this disease has never been observed, the death of the herd may amount to about 90% of the total population.
The pathogen virus is secreted by serological methods. The most frequently used for the diagnosis of enzyme immunoassay, 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 the full picture in the outbreak areas of the disease. But it is quite suitable for identifying disadvantaged cows to be imported into the country or into farms.
For diagnostic purposes, they can use polymerase chain reaction, which allows to isolate the serogroup and give the most accurate results. Blood sampling for laboratory diagnosis
When catarrhal fever cattle observed the following pathological changes:
- severe exhaustion of the whole organism
- poor circulation, which causes swelling of the lower body,
- inflammation of mucous membranes that have a bluish tint,
- the increase and blueness of the tongue, which often falls outside,
- the gums and internal cavities of the cheeks are affected by erosion, as well as sores,
- skeletal musculature has 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 found,
- dystrophic changes in the vascular endothelium, gastrointestinal mucosa and skeletal muscles.
Is it possible to cure
Unfortunately, there is currently no effective treatment for cattle against bluetongue. Treatment is more concerned with preventive measures. An important point is vaccination. Sick animals are given for slaughter.
An animal that has had catarrhal fever develops lifelong immunity to this virus serogroup. Corresponding antibodies appear in the blood that can be transmitted to the young 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. The development of immunity occurs after 10 days and lasts more than a year. During the vaccination period, cattle should be protected from the active sun. Vaccination is carried out on animals from three months of age.
Rules for the prevention and control of bluetooth
Such a disease is better to prevent than to cure. The main prevention against it is, as mentioned above, the timely vaccination against the disease. Disinfection of the barn, as a method for the prevention of bluetongue
To prevent the spread of infection, you should adhere to the following recommendations:
- use insecticidal drugs, as well as repellents,
- Do not walk a herd in swampy areas
- keep cattle in specialized barns year round,
- when purchasing a new livestock, observe a certain time quarantine,
- conduct serological diagnostics with a time interval of 20 days,
- control the quality of purchased sperm for fertilization,
- do not keep cattle with sheep in the same breeding room
- make regular prophylactic vaccinations, especially 30 days before the appearance of blood-sucking pests (midges, mosquitoes, ticks and others),
- conduct regular general examinations, take blood tests for timely detection of diseases,
- observe hygienic rules and carry out constant disinfection.
If, nevertheless, the disease is detected and the tests have shown a positive result, then the entire farm moves to quarantine, and the terrain within a radius of 150 km is considered to be unfavorable. This is due to the transmission of infection by mosquitoes, flies and other insects.
Quarantine is canceled only one year from the last recorded case of the disease and with normal results when taking tests for the presence of the causative agent. But diagnostics and vaccinations are carried out constantly in this zone and the territories nearest to it.
Blutang is a rare cow disease in our territory, but outbreaks of this disease are often recorded in Europe and have reached our territory. Purchased animals from other countries should be checked and vaccinations should be carried out if cases of this disease have been recorded somewhere near or on the farm.
The disease has been known since the end of the nineteenth century. For the first time, the disease was recorded and described in small cattle in South African countries. The causative agent was discovered in 1905. In the 1930s, the link between bluetongue and a similar disease in cattle was proved. Almost until the mid-twentieth century, the illness was considered solely a problem of the countries of the continent, which was first discovered.
Recently, mainly due to the import of animals and sheep products, it has become widespread. Registered in many countries in the Russian Federation refers to quarantine diseases.
Information about outbreaks of the disease periodically come from the territory of France, Germany, the Netherlands, Belgium and other European countries.
Upon receipt of information about the epizootic, 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 a wider distribution of bluetongue than is commonly believed. Ongoing research to identify specific antibodies in animals in many countries confirms this conjecture. In particular, serological evidence of the circulation of the causative agent was obtained in Canada, Mexico, Brazil, Iran and a number of other countries previously considered prosperous with respect to catarrhal fever.
Treatment and Prevention
Specific treatment for bluetongue is not developed. Sick sheep are sent for slaughter. In the case of high productive or breeding value and the feasibility of preserving animals with clinical signs are placed in a separate room, improve conditions of detention and feeding. Apply symptomatic therapy aimed at improving the general condition. Grazing of sick animals is prohibited, since ultraviolet irradiation provokes the aggravation of the pathological process. Certain therapeutic activity in bluetongue have drugs that contain arsenic compounds.
The basis of the fight against the disease is strict adherence to quarantine measures for the importation of animals. New arrivals are quarantined for 30 days. It is prohibited to import livestock and individuals from disadvantaged regions.
When an outbreak occurs, it is prohibited to graze in the evening (during the mass summer of the nasal season).
Measures are being taken to drain wetlands in the immediate vicinity of grazing, as well as to fight insects with insecticides and to protect small ruminants with repellents.
Susceptible livestock is subjected to active immunization with live and inactivated bluetongue vaccines. Vaccination is carried out once a year before pasture to pasture. Lambs up to the age of three months, obtained from ill and immunized mothers, have colostral immunity.