Central Scientific and Methodological Veterinary Laboratory. Bluetongue (febris catarrhalis ovium)

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

What kind of disease

Bluetongue is also called catarrhal fever or "blue tongue". This is a viral infection in which arthropods are involved. With it, inflammatory-necrotic lesions of the oral cavity, gastrointestinal tract, epithelium of the skin of the hooves 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 common 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-containing virus from the genus Orbivirus (family Reoviridae). The disease can be both single and large-scale. Sick animals serve as its source. 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 is most active on hot days. Most often it is recorded in swampy areas or in areas characterized by large quantity annual rainfall and stagnant water.

This disease is more susceptible to malnourished animals suffering from worms and infections. Crowding of animals and sunlight are also risk factors for occurrence.
Carrier of a viral infection - wood lice

Incubation period and signs

Bluetongue 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 course of the disease, the following symptoms are observed:

elevated temperature (+41-42 ° C), which lasts from 2 to 11 days;
redness, erosion and sores of the mucous membranes of the mouth;
increased salivation;
the smell of rot from the mouth;
purulent discharge from the nose;
swelling of the ears, lips, tongue, jaw, which gradually captures the neck and chest;
the tongue becomes purple or bluish over time, may hang down (not always);
pododermatitis;
lameness and curvature of the neck;
in advanced cases, diarrhea with bloody patches, great weight loss and weakness are observed.

The acute form of the disease usually takes 6–20 days and can be fatal for the animal on days 2–8 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 weight loss, poor quality of wool, 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 pathogen. In the Republic of South Africa, there is a vaccine containing 14 serotypes of this disease.

The subacute form can last about 30-40 days, and the chronic one bothers for more than a year. The animal with such a course of the disease gradually recovers, but fatal outcome not uncommon, especially in places where bluetongue appeared for the first time.
The abortive form is characterized by little elevated temperature, a slight lesion of the mucous membranes, although sometimes necrotic changes can be observed in the oral cavity. Cows are observed depression and a drop in milk production.

Usually such signs can be seen if vaccination was carried out, and the condition of the animal as a whole is quite satisfactory. Pregnant cows may miscarry or give birth to defective offspring. The infection is most dangerous for the embryo in the first three months of pregnancy.

Laboratory diagnostics

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

The virus of the causative agent of the disease is isolated using serological methods. Most often in recent times used for diagnosis linked immunosorbent assay, 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 outbreak areas. But it is quite suitable for identifying dysfunctional cows for import into the country or farms.

For diagnostic purposes, a polymerase chain reaction can be used to isolate the serogroup and give the most accurate results.

Pathological changes

In catarrhal fever of cattle, the following pathological changes are observed:

severe exhaustion of the whole organism;
circulatory disorders that cause swelling of the lower body;
inflammation of the mucous membranes, which have a bluish tinge;
an increase and cyanosis of the tongue, which often falls out;
gums and internal cavities cheeks are affected by erosion, as well as sores;
the musculature of the skeletal part 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 endothelium of blood vessels, mucous membranes of the gastrointestinal tract and skeletal muscles.

Is it possible to cure

Unfortunately, effective treatment cattle against bluetongue on this moment no. Treatment is more related to preventive measures. Vaccination is important. Sick animals are sent for slaughter.

Immunity

An animal that has been ill with catarrhal fever develops lifelong immunity to this virus serogroup. 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. The development of immunity occurs after 10 days and lasts for more than a year. During the vaccination period, cattle should be protected from the active sun. Vaccination is carried out for animals from the age of three months.

Important! Calves and lambs are recommended to be fedcolostrum from a vaccinated mother, notartificial substitutes, as they develop immunity to bluetongue, which lasts for 3-4 months.

Rules for the prevention and control of bluetongue

Such a disease is better to prevent than to cure. 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 insecticidal preparations, as well as repellents;
do not walk the herd in swampy areas;
keep livestock in specialized barns all year round;
when acquiring a new livestock, observe quarantine for a certain time;
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 room for breeding;
do regular preventive vaccinations, especially 30 days before the appearance of blood-sucking pests (midges, mosquitoes, ticks and others);
hold regular general examination take tests (blood) for timely detection diseases;
observe hygiene rules and carry out regular disinfection.

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

BLUETONGUE Bluetongue (blue tongue, bluetongue, bluetongue) is a viral transmissible disease of ruminants, characterized by damage to the mucous membrane of the oral and nasal cavities, swelling of the tongue, swelling of the front of the head, fever, and damage to the extremities. In cattle, abortions are possible, the birth of ugly offspring. AT vivo young sheep are most susceptible to the disease, less goats, cattle. It poses no danger to humans. Pigs, horses, dogs are not susceptible. The disease was first discovered in sheep in South Africa in 1876, and in 1905 the pathogen was discovered. In cattle, the disease was described in 1933. The first case of bluetongue registration in Russia occurred in 2007, when infected cattle from the Netherlands were brought to the Nizhny Novgorod farm. Etiology. The causative agent is a double-stranded RNA virus belonging to the genus Orbiviruses of the Reovirus family. There are 24 serotypes of the virus that have a common complement-fixing and precipitating antigens. The virus accumulates in the blood and hematopoietic organs of sick animals and can be transmitted transplacentally to the fetus. The maximum concentration of the virus is observed during the period of fever (3-9 days after infection). In some cases, the virus could be detected in the blood of sheep after 3-4 months, and in cattle - more than a year after infection. Cultivation - The virus reproduces in many cell cultures, in chick embryos and in newborn mice. The causative agent is stable in the external environment. In a blood sample, in a preservative solution, stored at room temperature, it remains viable for up to 25 years. Weak solutions of phenol do not inactivate the virus. At t 60 °C, the virus dies within 5 minutes. The virus is rapidly destroyed in acidic environment(pH below 6) and well preserved in alkaline (pH 8-9) Epizootology. sheep are most susceptible, and to a lesser extent cattle and goats. Of the wild animals - white-tailed deer, snow and bighorn sheep, antelopes and moose. Source - the main reservoir of the virus is cattle. This type of animal is more attractive to biting midges compared to sheep. Transmission factors of the pathogen - Transmission of the pathogen is possible only with the help of blood-sucking insects. Major carriers different types midges of the genus Culicoides, in salivary glands which the pathogen replicates. Virus replication in biting midges - 3 days at 300 C, 12-13 days at 200 C, more than 300 C - high death of biting biting. In addition to midges, mosquitoes, mosquitoes, and some types of ticks are carriers of the pathogen. Of the direct methods of infection, sexual transmission of the virus is possible; intrauterine infection has also been noted. Cattle are a natural reservoir of infection. Cows (especially adults) often carry the disease in a mild form without significant clinical changes. Bluetongue is characterized by seasonality, which is associated with the mechanism of transmission of the pathogen. The peak of infection occurs during the summer period of blood-sucking insects, the number of infections decreases in dry years. The disease is more widespread in areas with developed bolt and river systems. Course and symptoms Incubation period can last from 5 to 20 days. The course is observed: acute (sheep, deer), subacute (cattle, sheep in enzootic regions), asymptomatic (common in other animal species) forms. Clinical signs may vary by animal species, but nevertheless, the disease is more severe in small ruminants than in cattle: fever up to 42 degrees in the first days of the disease; - mucous membranes are edematous, reddened; -from mouth frothy saliva is secreted putrid smell; - there is a bilateral purulent discharge from the nasal passages; - swelling in the intermaxillary space, head, chest; - hemorrhages on the conjunctiva; - found on the oral mucosa ulcerative lesions; - respiratory disorders; - the tongue is enlarged in size, acquires a purple color, often hangs down (which is interesting "blue tongue" rare sign diseases). Pathological changes Dead animals - exhausted. Edema is noted lower divisions body (breast, intermaxillary space). The mucous membranes are inflamed, have a juicy texture, cyanotic color, with areas of hyperemia. Typical is the defeat of the oral cavity - the tongue is greatly enlarged, often falls out of the mouth and has a blue tint. on the gums and inner surface cheeks - erosion, weeping ulcers. The skeletal muscles are saturated with exudate, extensive foci of tissue death are noted. The myocardium is loose, the heart itself is enlarged, dropsy is often found, petechial hemorrhages on the epicardium. The defeat of the respiratory system is not typical, signs of bronchopneumonia occur due to concomitant diseases. Diagnosis Based on epizootological, clinical pathological, data, laboratory tests and bioassays. Serological methods are used - neutralization reaction, enzyme immunoassay. Rarely used PCR. AT diagnostic center send samples: spleen, lymph nodes (submandibular, mesenteric) blood and its serum. Economic damage The disease covers a large number of animals and is characterized by high mortality. When a disease occurs in previously prosperous areas, it is 70-90%, in stationary foci it ranges from 10 to 30%. In Spain, for example, in 1956 the disease swept over 200 farms in 4 months, and more than 130,000 sheep died. Significant damage is also caused by a decrease in productivity, loss of wool in sheep and a violation of the reproductive function. Clinically sick animals are sent for slaughter. Meat is used for canned products, sausages after boiling for 2.5 hours. Prevention and control measures. There are no specific control measures. In order to prevent the introduction of the pathogen into the country, a ban on the import of sheep, cattle and wild ruminants from countries affected by the disease is envisaged. Annual serological survey of sheep, cattle and deer, especially young animals of the current year of birth, on farms located in border areas. When importing susceptible animals from countries with an unknown epizootic situation or where bluetongue is detected, it is necessary to conduct a thorough serological, epidemiological and clinical examination, quarantine. Carry out disinfection and disinfection Vehicle from these countries. For disinfection, 3% solutions of formalin or sodium hydroxide are used. When a diagnosis is made (isolation of the pathogen, positive bioassay), quarantine is imposed on the farm, and the surrounding area (within a radius of 150 km) is considered unfavorable. Such a large coverage is associated with the peculiarities of the spread of infection - blood-sucking insects. In the threatened area, more than 0.5% of all susceptible flocks should be clinically examined and bled for serological diagnosis. It is forbidden to import animals into the quarantine area, and it is not allowed to export and drive susceptible species through the affected area. All livestock (large and small cattle) are immediately vaccinated. Clinically sick animals are sent for slaughter. Restrictions are lifted a year after the last case of a case and a subsequent negative laboratory test for the carriage of the virus. Subsequently, on the farm and adjacent territories, it is mandatory to carry out diagnostics and vaccination of livestock.

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

Rosselkhoznadzor detected the bluetongue virus in Russian cattle (cattle) in a five-kilometer zone around the farm in Smolensk region, in which earlier this year the same virus was detected in cattle imported from Germany, follows from the message of the department.

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 the base of the skin of hooves. , as well as dystrophy, changes in skeletal muscles.

For the first time, bluetongue was registered in South Africa in 1876, and at the beginning of the 20th 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 outbreaks of bluetongue in sheep and cattle come from the Netherlands, Belgium and Germany.

The causative agent of the disease is an RNA-containing 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 the infectious agent- sick animals. Virus reservoirs have not been established in nature. 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.

The carriers of the bluetongue virus are biting midges of the genus Culicoides, which determines the seasonal and stationary nature of the disease. It appears in early summer, peaks in the hot, rainy months, and disappears with the onset of frost.

The disease is recorded in swampy, low-lying areas, in areas with copious amounts annual precipitation.

The course of the disease is adversely affected by inadequate feeding, large crowding of animals, chronic infections, helminthiases, solar radiation.

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

In an acute course, 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; edema 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, putrefactive odor from the mouth.

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

Poddermatitis develops (inflammation of the base of the skin of the hoof), lameness, often there is a curvature of the neck and in severe cases- diarrhea with an admixture of blood, severe exhaustion and weakness.

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

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

Characterized by the exhaustion of animals, dryness and hair loss, damage to the limbs, lameness.

Sometimes there is a collapse of the horny shoe and bronchopneumonia caused by secondary infection, abortions in pregnant ewes.

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

The abortive course is characterized by a slight increase in body temperature, quickly 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 mucous membrane of the oral cavity and a decrease in milk yield with a satisfactory general condition of the body.

Recovered animals 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 next year.

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

For immunization, polyvalent live and inactivated vaccines are used.

Specific methods of treatment have not been developed.

Prevention and control measures

In disease-free countries, preventive measures are limited to prohibiting the importation of susceptible animals from bluetongue-prone countries, and quarantine domestic and wild ruminants at the points of entry.

In threatened zones 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 ones; carry out annual vaccination of animals.

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

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

12. Bluetongue in cattle and sheep

Catarrhal fever of sheep (febriscatarrhalisovium) - infectious disease, manifested by a feverish state, inflammatory-necrotic lesions digestive tract, language and degenerative changes skeletal muscles.

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

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

The latter is double-stranded, fragmented (consists of 10 fragments), does not possess infectivity and is not sensitive to RNAse.

epidemiological data. Sheep are most susceptible to catarrhal fever, especially young ones. Their sensitivity to the virus depends on the breed. Merinos and their crosses are more sensitive, Karakul and fat-tailed sheep are insensitive.

In stationary foci of the disease, sheep of imported breeds are more often affected; local ones are more resistant. Under laboratory conditions, it is possible to infect newborn mice and hamsters, which are injected with the virus into the brain.

Hiccup cattle are susceptible to the disease, but their disease proceeds 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 at the beginning of summer, usually with high humidity, and disappears with the onset of cold weather; not recorded in winter. The highest incidence of sheep is observed in the hot rainy months.

The disease is registered in swampy areas, in areas where there is a lot of rainfall. Usually, sheep become infected during their stay on pastures at night.

Inadequate feeding, large crowding in the room, chronic infections, helminthiases, solar exposure 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.

Uovets distinguish between acute, subacute, chronic course and abortive form of the disease.

Acute flow 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, outflow from the nasal cavity of serous or purulent exudate, which subsequently dries up with a crust, appear.

Edema develops in the ears, lips, sometimes tongue, intermaxillary region, spreading to the neck and chest. The lips become sore, the lower lip droops heavily.

On the mucous membrane of the oral cavity, there are hemorrhages, bleeding erosions, ulcers; due to tissue necrosis, a foul smell 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 used to be called a blue tongue. Often, in sick animals, the neck is bent, hair falls out, and in severe cases, bloody diarrhea appears. Lack of appetite, specific muscle lesions lead to severe emaciation, weakness, and deep asthenia.

In the subacute and chronic course of the disease, all symptoms develop slowly and are less pronounced. Characterized by exhaustion of animals, dryness and hair loss, damage to the limbs, accompanied by lameness.

Sometimes there is a fall of the horny shoe and bronchopneumonia caused by a secondary infection. The duration of the disease with a subacute course is 30-40 days, with chronic - 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, a rapidly 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 of clinical signs, pathological and anatomical changes and laboratory results.

Isolation of the virus (from the blood, spleen, lymph nodes) is carried out in the culture of kidney cells of lamb or hamster, in chicken embryos, which are infected intravenously, as well as in mice with intracerebral injection.

The bioassay will be carried out on two sheep, previously serologically tested for the absence of complement-fixing antibodies to the ucacariasis 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 for catarrhal fever of sheep is an increase in temperature to 41 ° C and above on the sixth to eighth day after infection, followed by the development of clinical signs of the disease. in all cases, virus isolation is confirmed 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 next year.

For prophylaxis, 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 catarrhal fever 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/

Bluetongue (febris catarrhalis ovium)

Bluetongue of sheep ( febris catarrhalis ovium) ("Blue tongue", bluetongue) is an infectious disease manifested by a feverish condition, 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 Reoviridae family, the Orbivirus genus.

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

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

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

epidemiological data. Sheep are most susceptible to catarrhal fever, especially young ones. Their sensitivity to the virus depends on the breed.

Merinos and their crosses are more sensitive, Karakul and fat-tailed sheep are insensitive.

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

Under laboratory conditions, it is possible to infect newborn mice and hamsters, which are injected with the virus into the brain. Cattle and goats are susceptible to the disease, but their disease proceeds without clinical symptoms.

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

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, large crowding in the room, chronic infections, helminthiases, solar exposure 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 course and abortive form of the disease are distinguished.
Acute course characterized by a sudden or gradual increase in body temperature up to 40.5-42°C.

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

Edema develops in the ears, lips, sometimes tongue, intermaxillary region, spreading to the neck and chest. The lips become sore, the lower lip droops heavily.

On the mucous membrane of the oral cavity, there are hemorrhages, bleeding erosions, ulcers; due to tissue necrosis comes ichorous smell from the mouth. A swollen and inflamed tongue turns purple or dirty blue and protrudes from the mouth.

For this reason, the disease was previously called blue tongue. Often, in sick animals, the neck is bent, hair falls out, in severe cases, it appears bloody diarrhea. Lack of appetite, specific muscle lesions lead to severe exhaustion, weakness, deep asthenia.

In the subacute and chronic course of the disease, all symptoms develop slowly and are less pronounced. Characterized by the exhaustion of animals, dryness and hair loss, damage to the limbs, accompanied by lameness.

Sometimes there is a collapse of the horn shoe and bronchopneumonia caused by a secondary infection. The duration of the disease with a subacute course is 30-40 days, with a chronic one - 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 of clinical signs, pathological changes and laboratory results.

Isolation of the virus (from the blood, spleen, lymph nodes) is carried out in the culture of kidney cells of lambs or hamsters, in chicken embryos, which are infected intravenously, as well as in mice with intracerebral injection.

The bioassay is placed 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 for catarrhal fever of sheep is an increase in temperature to 41 ° C and above on the sixth to eighth day after infection followed by the development of clinical signs of the disease. In all cases, the isolation of the virus 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. Recovered sheep 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 next year.

For prophylaxis, 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 catarrhal fever is not registered in the Republic of Belarus. Emphasis should be placed on strict controls on the importation 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 large. - presentation

1 bluetongue

2 Bluetongue (or bluetongue) refers to a group of exotic, particularly dangerous diseases of sheep and domestic and wild ruminants, such as cattle, goats, deer, mouflons, most species of African antelopes and various artiodactyls. Infectious catarrhal fever (Febris catarrhalis infectiosa, bluetongue, blue tongue, CBT) is a viral transmissible disease of ruminants, characterized by fever, inflammatory-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 skeletal muscles. Pregnant animals may have abortions and the birth of 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 History reference: The disease was first described in sheep in South Africa in 1876, and then in cattle (1933). Taylor 1905 discovered its causative agent.

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

outbreaks have been reported in India and Malaysia. In Canada, after being free from BT since 1976, this disease reappeared in the 1970s - worsening of the epizootic situation for 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.

head of cattle 2006 - BTV serotype 8 - Netherlands, Belgium, Germany, France and Luxembourg 2007 - further distribution of BTV-8 - UK, Denmark, Luxembourg

4 Map geographical distribution bluetongue

6 The causative agent is an RNA-containing virus belonging to the genus orbivirus of the Reoviriday family. The size of the virion is 68 nm. 24 serovariants are known. 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 on mice 1-2 days old, chicken embryos and in cultures of lambs kidney cells, VNK-21, where CPD is manifested.

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

Cattle are mostly asymptomatic.

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

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

In the inter-epidemic period, the virus apparently persists in the body of many species of wild ruminant cattle, among which a long-term circulation of the virus (over three years) has been established.

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

9 Pathogenesis The BT virus directly affects the muscle tissue and internal organs, causing profound changes in the vessels. As a result, violated metabolic processes. Animals get very thin. The disease is usually complicated by secondary infection.

The virus was found in the highest concentration 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 the parenchymal organs.

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

As a result, an abortion occurs or an ugly offspring is born.

11 Course and symptoms of acute subacute abortive The incubation period under natural conditions lasts about 7 days, in the experiment - 2-18 days. Forms of the course 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 outflows from the nasal cavity are observed.

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

In some animals, the tongue turns dark red to purple or purple which gave the disease its popular name. Nasal discharges become purulent, dry up around the nostrils, partially block the nostrils and make breathing difficult.

Edema extends to the muzzle, intermaxillary space, sometimes to the neck and chest. Pneumonia often develops, diarrhea with blood appears, and skin cracks form. Limbs are affected and lameness develops.

The defeat of the 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 condition of patients, sharp deterioration and animals die. This happens 3 weeks or more after the first signs of the disease appear.

13 SUBACTURE In a subacute course, severe emaciation, prolonged weakness, slow recovery, and sometimes a curvature of the neck are noted. The limbs are often affected, lameness is first noted, then purulent processes occur in the hoof area, and the horn shoe falls off. The illness lasts for days.

14 ABORTION Abortive course of the disease is characterized only by fever, superficial inflammation of the oral mucosa. More commonly seen in cattle. Recovery occurs relatively quickly.

Anorexia, swelling of the mucous membrane of the eyes, salivation, hyperemia of the mucous membrane of the oral and nasal cavities, and fever are observed in approximately 5 percent of cattle.

Ulcers are found on the nasal mirror, lips, gums, limbs, udder and vulva. The tongue is very swollen and protrudes from the mouth. After that, difficult swallowing is recorded. Animals die of thirst and pneumonia.

However, more often BT in cattle causes abortions and the birth of unviable ugly offspring.

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

Under the skin in the neck, shoulder blades and back, red gelatinous areas are found. Numerous hemorrhages are noted in muscle tissue, small intestine, myocardium, epicardium, mucous membranes 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 after 5 minutes. Weak solutions of phenol do not neutralize it. Acids, alkalis, chlorine-containing drugs inactivate the virus.

17 Diagnosis.

The disease is established on the basis of epizootological data (seasonality, association with insect vectors, predominantly affecting sheep, proceeds 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 on the tongue, hemorrhage in the muscle tissue, intestines), as well as, according to the results of a laboratory study, the detection of a virus and the detection of antibodies in recovered animals. The virus is isolated by infecting mice (intracerebrally), chicken embryos (intravenously), cell cultures. To clarify the diagnosis, they resort to setting up a bioassay, infecting a healthy sheep intravenously with blood suspicious of the disease of the animal. In all cases, virus isolation is confirmed by serological methods. Diffusion precipitation in agar gel, RIF, RSK, RDP are group-specific and allow the detection of antibodies to any type of virus; in RN and RPHA, antibodies to the homologous type are detected. An enzyme-linked immunosorbent assay has been developed for the detection of antigen and antibodies. Bluetongue should be suspected if the animals show fever, inflammatory lesions of the oral cavity, and profuse salivation taking into account the seasonal appearance of the disease during the mass attack of blood-sucking dipterous insects.

18 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 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, lesions of the eyes and upper respiratory tract are characteristic), necrobacteriosis (except for sheep, horses, pigs and other animals, chronic course, isolation of the pathogen), Ibaraki disease (cattle are sick, the results of virological and serological studies), epizootic hemorrhagic disease deer (virological and serological studies).

19 Immunity. Sheep that have recovered from illness acquire long-term and intense immunity only against the type of virus that caused the disease; protection against the heterologous type 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 BT from a strain of the virus modified by successive passages in sheep, as well as from strains of the virus passaged in chicken embryos, has been proposed.

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

Intense immunity and specific antibodies in high titer persist 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.

Mandatory is preventive quarantine with, if necessary, virological and serological studies.

In an area that is permanently unfavorable for infectious catarrhal fever of sheep, it is necessary to vaccinate a susceptible livestock at least a month before the onset of the disease season.

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

21 Treatment. Animal treatments have not been developed.

23 conjunctivitis

24 ulceration of the oral mucosa

28 Swelling of the facial part of the head

29 Edema and ulceration of the mucous membrane of the tongue

30 Damage to the teats of the udder in bovine CL

31 Paralysis and tongue prolapse

32 Desquamation of the epithelium of the nasal mirror in patients with cattle

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 in the territory Russian Federation it is necessary: not to import cattle from bluetongue-prone regions; carry out a serological survey for bluetongue of all cattle imported from bordering countries with disadvantaged and suspected bluetongue disease. If you suspect bluetongue, immediately inform the state veterinary service 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", approved by the Main Directorate of the Ministry of Agriculture of the USSR on March 27, 1974.

35 References Murueva G.B. “Natural foci of cptaral fever in sheep.” Sheep, goats, woolen business with Balysheva V.I., Slivko V.V., Zhesterev V.I. - “Cultivation of the bluetongue virus in animal cell cultures” with Strizhakov A.A.

"Creation of tools for epitomous 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 with Shoopala Johannes.

"Features of the manifestation of infectious bluetongue in Namibia." Veterinary medicine with Zharov A.V., Gulyukin M.I., Barabanov I.I.

"Pathological and histological studies in the monitoring system pathological processes in the body of farm animals, birds and fish. Veterinary consultant, 10.-s 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. "Bluetooth fever of sheep: problems of epizootic monitoring". Veterinary consultant p.4-7.

36 Thank you for your attention!

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

Bluetongue (bluetongue) - causes, symptoms and treatment

Bluetongue of sheep having enough exotic name"blue tongue" or "bluetongue" refers to viral diseases, is characterized a high percentage livestock damage, causes significant damage to sheep breeding.

The disease has been known since the end of the century before last. The disease was first reported and described in small ruminants in countries South Africa. The causative agent was discovered in 1905.

In the 1930s, a connection between bluetongue and a similar disease in cattle was proven.

Almost until the middle of the twentieth century, the disease was considered exclusively a problem of the countries of the mainland, on which it was first discovered.

Recently, mainly due to the import of animals and sheep products has become widespread. Registered in many countries, in the Russian Federation refers to quarantine diseases.

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

Upon receipt of information about the epizootic, the import of animals and related animal 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.

Ongoing studies on the detection of specific antibodies in animals in many countries confirm this conjecture.

In particular, serological evidence of the circulation of the causative agent of the disease was obtained in Canada, Mexico, Brazil, Iran and a number of other states that were previously considered safe in relation to 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.

Characteristic for them is the hexagonal shape and the presence of a loose, unstable outer shell. Accumulation of a pathogenic agent occurs in the blood, internal organs infected animal.

Transmission of the virus by the transplacental route has been noted.

In the laboratory, the virus replicates in chicken embryos, some cell cultures. Possible artificial infection of mice and hamsters. Sheep, goats, and less cattle are susceptible to natural infection. Of the wild, the disease is noted in:

moose;
deer;
wild sheep;
antelopes.

The main route of transmission of the virus is considered transmissible. The carriers of the virus are small blood-sucking families of midges, belonging to the components of the 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. They include high temperature environment and high humidity.

It is under the presence of these conditions that mass flying of insects and infection of susceptible animals occurs.

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

At the same time, in 1965, the possibility of infecting sheep with large doses of the virus by the alimentary route was proved. However, if such cases occur naturally, then they are of a single nature, 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 high susceptibility of young animals.

In adult animals, the disease often takes atypical forms that do not cause suspicion in the development of this particular disease.

In cattle, the disease proceeds easily, most often secretly. According to US veterinarians, less than 5% of infected cows are clinically affected.

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

The absence of a clinic and the long-term (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 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 blood of a sheep, 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 rise temperatures to values of 41-42°C (at a rate of 38.5-40°C in adult animals).

Within 1-2 days, catarrhal inflammation of the mucous membranes of the oral and nasal cavity develops, characterized by hyperemia of the mucous membranes, salivation, nasal discharge, shortness of breath, accompanied by sniffing and snorting.

This is followed by swelling of the lips, tongue, and ear area. In the oral cavity, on the lips, hemorrhages and ulcerations occur.

Accession of secondary microflora leads to the development purulent inflammation, noticeable bad smell from the oral cavity of the animal.

The lips hang down, a swollen purple-cyanotic tongue protrudes from the mouth.

Disorders of the digestive tract, a sharp emaciation, and sometimes hair loss are noted.

Death occurs against the background of general weakness and exhaustion.

Subacute and chronic forms develop in a similar way, with lesser severity of symptoms, their 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 carriers of the virus for some time, later the pathogen is eliminated from the blood, and a strong immunity to the type of pathogen with which the animal was infected develops.

Treatment and prevention

There is no specific treatment for bluetongue. Sick sheep are sent for slaughter.

In case of high productive or breeding value and expediency of keeping animals with clinical signs located in separate room improve the conditions of keeping and feeding.

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

Preparations containing arsenic compounds have a certain therapeutic activity in bluetongue.

The basis of the fight against the disease is strict observance quarantine measures for the importation of animals. New arrivals are quarantined for 30 days. It is forbidden to import livestock and individuals from disadvantaged regions.

In the event of an outbreak, grazing in the evening is prohibited (during the mass summer of midges).

Measures are being taken to drain wetlands in the immediate vicinity of pastures, as well as insect control with insecticides and the protection of small ruminants with the use of repellents.

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

Vaccination is done once a year before pasture.

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

Epizootic monitoring for bluetongue in cattle and small cattle

The Department of Virology and Laboratory Animals of the Federal State Budgetary Institution TsNMVL conducted an analysis of the 4-vet reports for 2016. According to the report, Russian veterinary laboratories conducted epidemiological monitoring for bluetongue in cattle and small cattle. A total of 44109 materials were received from KRS and MRS. The studies were carried out by PCR and ELISA methods. 564 positive results for blood serum by ELISA were obtained (163 - FGBU ARRIAH, 206 - Kaliningrad region, 2 - Tver region, 23 - Pskov region, 78 - Irkutsk region, 77 - Belgorod region, 8 - FGBU TsNMVL (Moscow region), 6 - Kemerovo region, 1 - Nizhny Novgorod region). positive results on PCR method not found.

Bluetongue (blue tongue, bluetongue) is a viral transmissible disease of ruminants, characterized by damage to the mucous membrane of the oral and nasal cavities, swelling of the tongue, swelling of the front of the head, fever, and damage to the limbs. In cattle, abortions are possible, the birth of ugly offspring.

The range of the disease is much wider than it is currently believed. The disease is often asymptomatic. Therefore, it is necessary to carry out an extensive program serological survey a large population to obtain at least indirect evidence of the presence or absence of the circulation of the virus. As a rule, several years pass before the final confirmation of the diagnosis by the isolation of the pathogen.

Using the neutralization reaction, 26 virus serotypes are distinguished, which have a common complement-fixing and precipitating antigens. The virus accumulates in the blood and hematopoietic organs of sick animals and can be transmitted transplacentally to the fetus. The maximum concentration of the virus is observed during the period of fever (3-9th day after infection). In some cases, the virus could be detected in the blood of sheep after 3-4 months, and in cattle - more than a year after infection.

One of the epizootological features of bluetongue is its natural focal character. The circulation of the virus in the body of carriers and wild ruminants ensures the existence of persistent natural foci and determines the stationarity of the disease.

The biological transmission of the pathogen underlies the seasonal appearance and spread of catarrhal fever. The disease appears only in the summer and spreads most intensively in years with a damp and warm climate, especially in areas with wetlands where there is a lot of rainfall. In the absence of insects - biological carriers of the virus, the disease does not spread. The main carriers of the virus are different types of biting midges of the genus Culicoides. In the USA it is S. variipenis, C. brevitarsis in Australia (Jones, 1966; Luedke, 1967; Foster, 1968).

Three ways of transmission of the virus are known: 1) horizontal - from animal to animal with the help of carriers; 2) vertical - from mother to fetus through the placenta; 3) horizontal-vertical - transmission of the virus to cows with infected sperm during mating, and then vertical transmission from mother to fetus through the placenta.

The main reservoir of the bluetongue virus is cattle. This type of animal is more attractive to biting midges as a host compared to sheep.

For the diagnosis of bluetongue, PCR, ELISA, RSK, MFA (fluorescent antibody method) and the agar gel diffusion precipitation reaction (RDP) can be used.

On the issue of the need for immunization of cattle, experts do not have a unanimous opinion, and there are no vaccines tested for these purposes. Even under experimental conditions, the possibility and expediency of using vaccine preparations used in sheep breeding have not been studied.