Bluetongue (febris catarrhalis ovium) (blue tongue, bluetongue). Bluetongue (catarrhal fever) cattle
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Presentation on the topic: bluetongue
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Bluetongue (or catarrhal fever sheep) belongs to the group of exotic highly dangerous diseases of sheep and domestic and wild ruminants, such as large cattle, goats, deer, mouflons, most species of African antelopes and various artiodactyls. 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, CLO) is a viral transmissible disease of ruminants, characterized by fever, inflammatory-necrotic lesions digestive tract, especially the tongue, corolla epithelium and the base of the skin of the hooves, as well as degenerative changes skeletal muscles. Pregnant animals may have abortions and the birth of malformed offspring. Clinical manifestations diseases and morphological changes vary depending on the pathogenicity of the strain, individual features and breeds of animals, the influence of environmental conditions (meteorological factors, solar radiation, etc.).
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The disease was first described in sheep in South Africa in 1876, and then 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 1987-1988. outbreaks have been reported in India and Malaysia. In Canada, after being free of TB since 1976, the disease reappeared in 1987-1988. 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. The largest number of outbreaks was noted in South Africa and Israel. For the first time in 1987-1988. outbreaks have been reported in India and Malaysia. In Canada, after being free of TB since 1976, the disease reappeared in 1987-1988. 1998 - 2005 - deterioration of the epizootic situation of 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 spread of BTV-8 - UK, Denmark, Luxembourg
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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 of 1-2 days of age, chicken embryos and in cultures of lambs kidney cells, VNK-21, where CPD is manifested. - 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 of 1-2 days of age, chicken embryos and in cultures of lambs kidney cells, VNK-21, where CPD is manifested.
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AT vivo 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. 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 bluetongue 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 a more severe course of the disease in animals exposed to solar radiation. Biological carriers of the virus different kinds midges of the genus Culicoides; sheep bloodsucker Melophagus ovinus (mechanical vector). During the inter-epizootic 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 during 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.
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The BTV virus directly affects muscle tissue and internal organs, causing deep changes in the vessels. As a result, violated metabolic processes. Animals get very thin. The disease is usually complicated by secondary infection. The BTV virus directly affects the muscle tissue and internal organs, causing profound changes in the vessels. As a result, metabolic processes are disrupted. 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 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.
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Acute course 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 discharges 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. Defeat oral cavity and gastrointestinal tract lead to exhaustion. After 3-4 weeks, the hair begins to fall out. AT 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. 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 discharges 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 purplish or violet, giving 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, a sharp deterioration occurs and the animals die. This happens 3 weeks or more after the first signs of the disease appear.
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At subacute course note severe exhaustion, prolonged weakness, slow recovery, sometimes a curvature of the neck. 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 15-30 days. In the subacute course, severe exhaustion, prolonged weakness, slow recovery, and sometimes neck curvature 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 15-30 days.
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The 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. The 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.
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The corpse is emaciated. The mucous membranes of the oral cavity and tongue are hyperemic, cyanotic, edematous with numerous hemorrhages. The epithelium is desquamated, 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. The corpse is emaciated. The mucous membranes of the oral cavity and tongue are hyperemic, cyanotic, edematous with numerous hemorrhages. The epithelium is desquamated, 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 the muscle tissue, small intestine, myocardium, epicardium, on the mucous membranes of the respiratory tract, bladder and ureters.
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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. 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.
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The disease is established on the basis of epizootological data (seasonality, association with insect vectors, predominant lesion 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), pathoanatomical changes (necrosis of the mucous membranes, erosion and ulcers in the oral cavity and tongue, hemorrhage in the muscle tissues, 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 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 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 was confirmed 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. Designed enzyme immunoassay for antigen and antibody detection. 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.
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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, a 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 are sick, 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). 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), necrobacillosis (horses, pigs and other animals are sick in addition to sheep, chronic course, pathogen excretion), Ibaraki disease (bovine livestock, results of virological and serological studies), epizootic hemorrhagic disease of deer (virological and serological studies).
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.
Incubation period 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 putrid smell from 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, neck curvature often appears and, in severe cases, diarrhea mixed with 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 disease with subacute course is 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 oral mucosa and a decrease in milk yield with satisfactory general condition organism.
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 from mother's milk) for up to 3 months. For immunization, polyvalent live and inactivated vaccines.
Specific methods of treatment have not been developed.
Prevention and control measures
In disease-free countries preventive actions are limited to prohibition of importation of susceptible animals from bluetongue-prone countries, quarantine of domestic and wild ruminants at 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
In order to significantly increase the efficiency of the Agro-industrial complex in animal husbandry, Russia is importing a large number of pedigree highly productive livestock 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 the Smolensk region, a bovine bluetongue virus of an unknown serotype was detected. Initially, the virus was detected on 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 subjects of the Russian Federation, as well as from Russian cattle, which is kept in a 5-kilometer zone around the farm in the Smolensk region, where this cattle was imported from Germany. “Currently, data have been received that there are Russian cattle in the 5-kilometer zone around this farm, which are also infected with the same bluetongue virus.”
Bluetongue ("blue tongue", bluetongue) is a zooanthroponotic natural focal disease. Under natural conditions, sheep, cattle, deer, camels, buffaloes, goats and some other species of wild ruminants are susceptible to infection with the virus.
The first report of the disease in sheep with symptoms of bluetongue was received from South Africa in 1876. For 135 years, the disease has spread globally, periodically manifesting itself in the form of mass epizootics among susceptible animals Analysis of the epizootic situation of bluetongue in the world for last years indicates that the area of infection is constantly expanding. According to the OIE, by 1937 the disease was registered in 13 African countries, and 10 years later - in more than 80 countries of the Western and Eastern Hemisphere. In recent years, the disease has taken on new dimensions, 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, and also in 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 disadvantaged area. The infection can be simultaneously among cattle and sheep in mixed farms. There are currently 24 known serotypes.
An important epizootological feature of bluetongue, which greatly complicates the fight against the disease, is the ability of the virus to form natural foci even when it is once introduced into a certain territory.
Bluetongue is a viral transmissible disease of ruminants, characterized by a feverish condition, inflammatory-necrotic lesions of the oral cavity, digestive tract, corolla epithelium and the base of the skin of the hooves.
The carriers of the causative agent of bluetongue are several types of midges, mosquitoes, mites and sheep bloodsuckers.
Bluetongue, or "blue tongue", is not dangerous to humans, but among animals it can cause epizootics and mass deaths. Mortality in this disease can reach 90-100%.
The economic impact of bluetongue in primary focus amounts to direct losses (death and forced slaughter of animals) and the costs of conducting anti-epizootic measures, in stationary - direct losses, reduced 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 other products of animal origin.
Diagnosis of bluetongue is made on the basis of data from epizootological, clinical and post-mortem examinations, as well as the results of laboratory research- isolation of the virus from the organs and tissues of sick individuals, or the detection of virus-specific antibodies in the blood serum of sick animals.
In order to reduce the risk of introduction and eliminate the possibility of bluetongue spreading on the territory of the Russian Federation, it is necessary: serological survey on bluetongue of all cattle, which are imported from countries bordering on disadvantaged and suspected of being unfavorable for bluetongue.
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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 (Febriscatarrhalisinfectiosa, bluetongue, blue tongue, CBT) is a viral transmissible disease of ruminants, characterized by fever, inflammatory-necrotic lesions of the digestive tract, especially the tongue, epithelium of the corolla and the 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.).
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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. The largest number of outbreaks was noted in South Africa and Israel. For the first time in 1987-1988. outbreaks have been reported in India and Malaysia. In Canada, after being free of TB since 1976, the disease reappeared in 1987-1988. 1998 - 2005 - worsening of the epizootic situation of 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 spread of BTV-8 - UK, Denmark, Luxembourg
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Map of the geographic distribution of bluetongue
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Pathogen
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 of 1-2 days of age, chicken embryos and in cultures of lambs kidney cells, VNK-21, where CPD is manifested.
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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 bluetongue 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 a more severe course of the disease in animals exposed to solar radiation. Biological carriers of the virus are various species of 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 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 during 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.
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Pathogenesis
The BTV virus directly affects the muscle tissue and internal organs, causing profound changes in the vessels. As a result, metabolic processes are disrupted. Animals get very thin. 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, then in the blood (associated with erythrocytes). 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.
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Course and symptoms
The incubation period under natural conditions lasts about 7 days, in the experiment - 2-18 days. Forms of the course 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 discharges 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 purplish or violet, giving 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, a sharp deterioration occurs and the animals die. This happens 3 weeks or more after the first signs of the disease appear.
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SUBACTURAL
In the subacute course, severe exhaustion, prolonged weakness, slow recovery, and sometimes neck curvature 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 15-30 days.
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ABORTIVE
The 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.
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pathological changes.
The corpse is emaciated. The mucous membranes of the oral cavity and tongue are hyperemic, cyanotic, edematous with numerous hemorrhages. The epithelium is desquamated, 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 the muscle tissue, small intestine, myocardium, epicardium, on the mucous membranes of the respiratory tract, bladder and ureters.
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Sustainability
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.
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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 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. Catarrhal fever of sheep should be suspected when animals are found to have 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 Diptera.
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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 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), necrobacillosis (horses, pigs and other animals are sick in addition to sheep, chronic course, pathogen excretion), Ibaraki disease (bovine livestock, results of virological and serological studies), epizootic hemorrhagic disease of deer (virological and serological studies).
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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.
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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. 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.
slide 21
Treatment.
Animal treatments have not been developed.
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Bluetongue (bluetonge) It is an infectious, non-contagious disease of cattle, sheep, goats and wild ruminants. Under the names "blue tongue". According to the OIE classification, it is classified as a dangerous disease.
Bluetongue disease in cattle was first reported on the African continent in South Africa and was almost asymptomatic among local cattle. It acquired a malignant character in connection with the importation to Africa of European sheep breeds highly sensitive to the pathogen.
Outside the African continent, the disease has been recorded since 1943.
The causative agent of the disease is a virus of the genus Orbivirus of the Reoviriclae family. The serogroup of the Bluetongue virus includes 24 serotypes.
Heating to 60 C◦ inactivates the virus in 5 minutes, treatment with 3% sodium hydroxide solution and 70◦ alcohol in 5 minutes.
In beef, mutton, at a meat pH of 5.6-6.3, the virus is quickly inactivated, and in meat at a pH above 6.3, it persists for up to 30 days. In the blood, in an aqueous 1% phenol solution with the addition of 1% potassium oxalate at room temperature the virus persists for several years. It is well preserved when dried, as well as at temperatures below minus 20 C. Slow freezing to minus 10 C◦ or to minus 20 C◦ destroys the virus.
The virus is found in blood, plasma, serum and hematopoietic organs sick animals. The causative agent of the disease is transmitted from sick to healthy animals blood-sucking insects. It is enough to introduce 0.01 ml of blood containing the virus into the animal's blood to cause the disease. Experimentally it is possible to infect animals when the material is administered orally, intranasally, intravenously, intraperitoneally, intradermally, subcutaneously, intracerebral and intramuscularly.
Bluetongue disease is seasonal and coincides with the period of the greatest activity of insects. The main carriers of the pathogen are biting midges (Culscosdes variipenniss uc.des.brevitaris), which are widespread almost everywhere, carrying both pathogenic and vaccine viruses. Mosquitoes, mosquitoes and bloodsuckers are involved in the spread of the virus. Migratory birds may be an intermediate through which insects indirectly transmit the virus from virus carriers to susceptible animals. The most significant reservoir of the virus in nature are cattle, as well as bighorn elks, sheep, antelopes, white-tailed deer, some rodents, on which biting midges mainly feed.
Young animals are more susceptible to the disease. The severity of the course of the disease depends on the pathogenicity of the strains and the breed of the animal. 6-8 days after infection, an increase in body temperature to 40.5-42.0°C is observed and is maintained at this level for 6-12 days.
The temperature level does not correlate with the severity of the process. With a slight increase in body temperature, death can occur and. on the contrary, when high temperature(42.0°С) may occur fast recovery. After 24-48 hours from the moment the temperature rises, conjunctivitis develops, hyperemia and swelling of the skin of the muzzle, hyperemia of the mucous membranes of the oral and nasal cavities with the appearance pinpoint hemorrhages and the formation of ulcers. The muzzle of the animal is constantly wet due to nasal discharge, saliva and constant licking.
Intensive hyperemia of the tongue is noted before the development of edema, cyanosis and prolapse of the tongue from the mouth, which served as the name of the disease "blue tongue" in the Russian version. in the groin and axillary areas skin hyperemia develops. Dermatitis develops, leading to hair loss. On the hind limbs develop hyperemia and painful swelling hoof corolla, which leads to lameness, immobilization and atrophy of muscle tissue. Nasal discharge becomes purulent, dry around the mouth in the form of a crust. Because of mouth ulcers, animals cannot drink, eat, and because of pain in the legs they cannot move. Progressive exhaustion is observed for up to 10 days with the development of a state of prostration and death. If the animal survives, then 10-15 days after the normalization of body temperature, a visible improvement in health occurs, and after 3-4 weeks the hair begins to fall out. In cattle with the initial introduction of the pathogen Clinical signs reminiscent of yashur. In enzootic zones in cattle, the disease occurs more often in latent form. In lambs, pneumonia is noted, leading to death. Mortality among animals reaches 2-30%. but with the initial introduction of infection can reach 100%.
For the reason that. that the causative agent of Bluetongue is able to cross the placenta, in sick animals, muhsfication of embryos, disturbances in the development of fetuses and the birth of non-viable calves and lambs are noted.
At autopsy of the corpses of ruminants that died from Bluetongue, gelatinous edema of the tissues of the head, lips, tongue, and pharynx is noted. larynx and intermaxillary region. The edematous fluid is gelatinous. with an admixture of blood, is also found in the chest and abdominal cavities, and in the pericardium. The mucous membranes of the oral cavity are edematous, cyanotic, covered with hemorrhages. but on the lips, tongue and inner surface cheeks - ulcers. Mucous membranes of the stomach and pancreas, thin department intestines are hyperemic with hemorrhages. The spleen is enlarged, filled with blood, juicy on the cut.
Lymph nodes are enlarged, hyperemic. juicy cut. Intermuscular connective tissue soaked in a red gelatinous liquid.
Diagnosis is based on epizootic data, clinical picture diseases, pathological changes and laboratory results. To make a final diagnosis, it is necessary to isolate the virus and identify it with a bioassay.
Recovered animals acquire lifelong immunity to the serotype of the virus that caused the disease, but it is possible for this animal to be re-infected with another serotype. Used to immunize animals live vaccine"Alexander" from 4 strains, developed in 1947.
In South Africa, a culture vaccine has been developed from 14 serotypes of the virus. There are mono- and bivalent vaccines. Live vaccines do not meet requirements due to co-circulation in nature more serotypes of the pathogen than is present in the vaccine, and, according to researchers, manifestations of virus reversibility. Due to the high reactogenicity of live vaccines, the appearance of recombinant strains in the case of the use of polyvalent vaccines, scientists recommend inactivated vaccines in practice. Such vaccines have been developed in the world that protect animals from 3-4 virus serotypes and provide stable immunity throughout the year.
