Bluetongue in ruminants; cause, symptom, prevention and control

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Bluetongue in ruminants; cause, symptom, prevention and control

Bluetongue in ruminants; cause, symptom, prevention and control Bluetongue is caused by the pathogenic virus, Bluetongue virus (BTV),[3] of the genus Orbivirus, of Unlike other arboviruses, BTV lacks a lipid envelope.

Bluetongue is caused by the pathogenic virus, Bluetongue virus (BTV),[3] of the genus Orbivirus, of the Reoviridae family. Twenty-six serotypes are now recognised for this virus.[7]

The virus particle consists of ten strands of double-stranded RNA surrounded by two protein shells. The particle has a diameter of 86 nm.[8] The structure of the 70 nm core was determined in 1998 and was at the time t

he largest atomic structure to be solved.[9]

The two outer capsid proteins, VP2 and VP5, mediate attachment and pe*******on of BTV into the target cell. The virus makes initial contact with the cell with VP2, triggering receptor-mediated endocytosis of the virus. The low pH within the endosome then triggers BTV's membrane pe*******on protein VP5 to undergo a conformational change that disrupts the endosomal membrane.[8] Uncoating yields a transcriptionally active 470S core particle which is composed of two major proteins VP7 and VP3, and the three minor proteins VP1, VP4 and VP6 in addition to the dsRNA genome. There is no evidence that any trace of the outer capsid remains associated with these cores, as has been described for reovirus. The cores may be further uncoated to form 390S subcore particles that lack VP7, also in contrast to reovirus. Subviral particles are probably akin to cores derived in vitro from virions by physical or proteolytic treatments that remove the outer capsid and causes activation of the BTV transcriptase. In addition to the seven structural proteins, three non-structural (NS) proteins, NS1, NS2, NS3 (and a related NS3A) are synthesised in BTV-infected cells. Of these, NS3/NS3A is involved in the egress of the progeny virus. The two remaining non-structural proteins, NS1 and NS2, are produced at high levels in the cytoplasm and are believed to be involved in virus replication, assembly and morphogenesis.[3]

02/10/2022

Bluetongue (BT) is a haemorrhagic disease of wild and domestic ruminants with a huge economic worldwide impact on livestock. The disease is caused by BT-virus transmitted by Culicoides biting midges and disease control without vaccination is hardly possible. Vaccination is the most feasible and cost-effective way to minimize economic losses. Marketed BT vaccines are successfully used in different parts of the world. Inactivated BT vaccines are efficacious and safe but relatively expensive, whereas live-attenuated vaccines are efficacious and cheap but are unsafe because of under-attenuation, onward spread, reversion to virulence, and reassortment events. Both manufactured BT vaccines do not enable differentiating infected from vaccinated animals (DIVA) and protection is limited to the respective serotype. The ideal BT vaccine is a licensed, affordable, completely safe DIVA vaccine, that induces quick, lifelong, broad protection in all susceptible ruminant species. Promising vaccine candidates show improvement for one or more of these main vaccine standards. BTV protein vaccines and viral vector vaccines have DIVA potential depending on the selected BTV antigens, but are less effective and likely more costly per protected animal than current vaccines. Several vaccine platforms based on replicating BTV are applied for many serotypes by exchange of serotype dominant outer shell proteins. These platforms based on one BTV backbone result in attenuation or abortive virus replication and prevent disease by and spread of vaccine virus as well as reversion to virulence. These replicating BT vaccines induce humoral and T-cell mediated immune responses to all viral proteins except to one, which could enable DIVA tests. Most of these replicating vaccines can be produced similarly as currently marketed BT vaccines. All replicating vaccine platforms developed by reverse genetics are classified as genetic modified organisms. This implies extensive and expensive safety trails in target ruminant species, and acceptance by the community could be hindered. Nonetheless, several experimental BT vaccines show very promising improvements and could compete with marketed vaccines regarding their vaccine profile, but none of these next generation BT vaccines have been licensed yet.

02/10/2022

Supportive care of blue tooth
Prevention
There is no specific treatment for animals with bluetongue apart from rest, provision of soft food, and good husbandry. Complicating and secondary infections should be treated appropriately during the recovery period.
Prophylactic immunization of sheep remains the most effective and practical control measure against bluetongue in endemic regions. Attenuated and inactivated vaccines against BTV are commercially available in some countries. Three polyvalent vaccines, each comprising five BTV serotypes, are widely used in southern Africa and elsewhere. A monovalent (BTV type 10) modified live virus vaccine is available for use in sheep in the US. Use of vaccines with different serotypes does not provide consistent cross-protection. Live, attenuated virus vaccines should not be used during Culicoides vector seasons because these insects may transmit the vaccine viruses from vaccinated to nonvaccinated animals (eg, other ruminant species). The result may be reassortment of genetic material, giving rise to new viral strains. Passive immunity in lambs usually lasts 2–4 months.
Control of bluetongue is different in areas where the disease is not endemic. During an outbreak, when one or a limited number of serotypes may be involved, vaccination strategy depends on the serotypes causing infection. Use of vaccine strains other than those causing infection affords little or no protection and is not recommended. The potential risk from vaccine virus reassortment with wild-type viral strains, virus transmission by the vectors to other susceptible ruminants, and reversion to virulence of vaccine virus strains or even the production of new BTV strains of uncertain virulence should also be considered. The use of inactivated vaccines in BTV incursions into northern Europe has played a major part in controlling virus transmission in those regions where extensive vaccination rates (>80%) have been achieved.
Control of vectors by the use of insecticides or protection from vectors may lower the number of Culicoides bites and subsequently the risk of exposure to BTV infection. However, these measures alone are unlikely to effectively halt a bluetongue epidemic and should be regarded as mitigation measures to be used alongside a comprehensive and vigorous vaccination program.

02/10/2022

Diagnosis of Bluetongue in Ruminants
Clinical evaluation
Postmortem examination
Virus identification
Serologic testing
The typical clinical signs of bluetongue enable a presumptive diagnosis, especially in areas where the disease is endemic.
Suspicion is confirmed by the presence of petechiae, ecchymoses, or hemorrhages in the wall of the base of the pulmonary artery and focal necrosis of the papillary muscle of the left ventricle. These highly characteristic lesions are usually obvious in severe clinical infections; in mild or convalescent cases, however, they may be barely visible. These lesions are often described as pathognomonic for bluetongue, but they also occur occasionally in other ovine diseases, such as heartwater, pulpy kidney disease, and Rift Valley fever. Hemorrhages and necrosis are usually found where mechanical abrasion damages fragile capillaries, such as on the buccal surface of the cheek opposite the molar teeth and the mucosa of the esophageal groove and omasal folds. Other necropsy findings include subcutaneous and intermuscular edema and hemorrhages, skeletal myonecrosis, myocardial and intestinal hemorrhages, hydrothorax, hydropericardium, pericarditis, and pneumonia.
Laboratory confirmation of bluetongue is based on virus isolation in embryonated chicken eggs or mammalian and insect cell cultures, or on identification of viral RNA by PCR assay. The identity of isolates may be confirmed by group-specific antigen-capture ELISA, group-specific PCR assay, immunofluorescence, immunoperoxidase technique, serotype-specific virus neutralization tests, serotype-specific PCR assay, or hybridization with complementary gene sequences of group- or serotype-specific genes. For virus isolation, blood (10–20 mL) is collected as early as possible from febrile animals into an anticoagulant such as heparin, sodium citrate, or ethylenediaminetetraacetic acid (EDTA) and transported at 4°C (39.2°F) to the laboratory. For long-term storage when refrigeration is not possible, blood is collected in oxalate-phenol-glycerin (OPG). Blood to be frozen should be collected in buffered lactose peptone and stored at or below −70°C (−94°F). Blood collected later during the viremic period should not be frozen because lysing of the RBCs on thawing releases the cell-associated virus, which may then be neutralized by early humoral antibody. The virus does not remain stable very long at −20°C (−4°F). In fatal cases, specimens of spleen, lymph nodes, or red bone marrow are collected and transported to the laboratory at 4°C (39.2°F) as soon as possible after death.
A serologic response in ruminants can be detected 7–14 days after infection by BTV and is generally lifelong after a field infection. Current recommended serologic techniques for detection of BTV antibody include agar gel immunodiffusion (AGID) and competitive ELISA. The latter is the test of choice and does not detect cross-reacting antibody to other orbiviruses, especially anti-EHDV (epizootic hemorrhagic disease virus) antibody. Various forms of the serum neutralization test, including plaque reduction, plaque inhibition, and microtiter neutralization, can be used to detect type-specific antibody.

02/10/2022

Clinical Findings of Bluetongue in Ruminants
The course of bluetongue in sheep can vary from peracute to chronic, with a mortality rate of 2%–90%. Peracute cases die within 7–9 days of infection, mostly as a result of severe pulmonary edema leading to dyspnea, frothing from the nostrils, and death by asphyxiation. In chronic cases, sheep may die 3–5 weeks after infection, mainly because of bacterial complications (especially pasteurellosis) and exhaustion. Animals with mild cases usually recover rapidly and completely. The major production losses include deaths, unthriftiness during prolonged convalescence, wool breaks, and reproductive losses.
In sheep, BTV causes vascular endothelial damage, resulting in changes to capillary permeability and subsequent intravascular coagulation, leading to edema, congestion, hemorrhage, inflammation, and necrosis. The clinical signs in sheep are typical. After an incubation period of 4–6 days, a fever of 40.5°–42°C (105°–107.5°F) develops. Affected animals are listless and reluctant to move. Clinical signs in young lambs are more apparent, and the mortality rate can be high (up to 30%). Approximately 2 days after onset of fever, additional clinical signs may be evident, such as edema of the lips, nose, face, submandibular area, eyelids, and sometimes ears; congestion of mouth, nose, nasal cavities, conjunctiva, and coronary bands; and lameness and depression. A serous nasal discharge is common, later becoming mucopurulent. The congestion of nose and nasal cavities produces a “sore muzzle” effect, the term used to describe the disease in sheep in the US.
Sheep eat less because of oral soreness and will hold food in their mouths to soften before chewing. They may champ to produce a frothy oral discharge at the corners of the lips. On close examination, small hemorrhages are visible on the mucous membranes of the nose and mouth. Ulceration develops where the teeth come in contact with lips and tongue, especially in the areas of most friction. Some affected sheep have severe swelling of the tongue, which may become cyanotic (hence the term "blue tongue”) and even protrude from the mouth. Animals walk with difficulty as a result of inflammation of the hoof coronets. A purple-red color is obvious as a band at the junction of the skin and the hoof. Later in the course of disease, lameness or torticollis develops due to skeletal muscle damage. In most affected animals, abnormal wool growth results from dermatitis.
Clinical signs of bluetongue in cattle are rare but may be similar to those that occur in sheep. They are usually limited to fever, increased respiratory rate, lacrimation, salivation, stiffness, oral vesicles and ulcers, hyperesthesia, and a vesicular and ulcerative dermatitis. Susceptible cattle and sheep infected during pregnancy may abort or deliver malformed calves or lambs. The malformations include hydranencephaly or porencephaly, which results in ataxia and blindness at birth. White-tailed deer and pronghorn antelope develop severe hemorrhagic disease leading to sudden death.
In many areas of the world, BTV infection in sheep, and especially in other ruminants, is subclinical. Although clinical signs in cattle are rare and limited, exposure to BTV can influence international trade and movement of serologically positive animals.

02/10/2022

Epidemiology and Transmission of Bluetongue in Ruminants
There are at least 29 serotypes of BTV worldwide, although not all serotypes exist in any one geographic area. Distribution of BTV throughout the world parallels the spatial and temporal distribution of vector species of Culicoides biting midges (the only important natural transmitters of the virus) as well as the temperatures at which BTV will replicate in and be transmitted by these vectors. Continued cycling of the virus among competent Culicoides vectors and susceptible ruminants is critical to viral ecology. In the US, the principal vectors are C sonorensis and C insignis, which limit the distribution of BTV to southern and western regions. In northern and eastern Australia, the principal vector is C brevitarsis, whereas in Africa, southern Europe, and the Middle East, it is C imicola. In northern Europe, the major vectors are species within the C obsoletus-dewulfi complex. In each geographic region, secondary vector species may attain local importance.
Vectors become infected with BTV by imbibing blood from infected vertebrates; transovarial transmission has not been reported. The high affinity of the virus to blood cells, especially the sequestering of viral particles in invaginations of RBC membranes, contributes to prolonged viremia in the presence of neutralizing antibody. The extended viremia in cattle (occasionally up to 11 weeks), as well as the host preference for cattle that some vector species of Culicoides display, provides a mechanism for year-round transmission in domestic ruminants in locations where the vector-free period (ie, winter) is relatively short. Mechanical transmission by other bloodsucking insects is of minor importance.
Vector-borne transmission through Culicoides spp is the primary way that BTV is transmitted. Virus concentrations in secretions and excretions are minimal, making direct, indirect, or aerosol transmission unlikely. However, in-contact transmission of BTV serotype 26 has been demonstrated in goats. The importance of this form of transmission in the ecology of this serotype is not known. Semen from viremic bulls can serve as a source of infection for cows through natural service or artificial insemination. Embryo transfer is regarded as safe, provided that donors are not viremic and an appropriate washing procedure for embryos is used. Transplacental transmission of field strains of BTV from dam to fetus, leading to the birth of viremic calves, is reported in cattle; however, the epidemiological importance of this mechanism is unclear. Bluetongue is listed by the World Organisation for Animal Health (OIE) as a notifiable disease. Bluetongue virus is not zoonotic.

02/10/2022

Bluetongue is a viral disease of ruminants worldwide. Clinical signs in sheep result from vascular endothelial damage, including edema of the muzzle, tongue, and coronary bands. Diagnosis is made on clinical suspicion and viral identification. Control and prevention measures consist of vaccination, where available, and vector control.
Bluetongue is a noncontagious, infectious, arthropod-borne viral disease primarily of domestic and wild ruminants. Infection with bluetongue virus (BTV) is common in a broad band across the world, which until recently stretched from ~35°S to 40°–50°N. Since the 1990s, BTV has extended considerably north of the 40th and even the 50th parallel in some parts of the world (eg, Europe). The geographic restriction is in part related to the climatic and environmental conditions necessary to support the Culicoides vectors. Most infections with BTV in wild ruminants and cattle are subclinical. Bluetongue (the disease caused by BTV) is usually considered to be a disease of improved breeds of sheep, particularly the fine-wool and mutton breeds, although it has also been recorded in cattle and some wild ruminant species, including white-tailed deer (Odocoileus virginianus), pronghorn antelope (Antilocapra americana), and desert bighorn sheep (Ovis canadensis) in North America, and European bison (Bison bonasus) and captive yak (Bos grunniens grunniens) in Europe.

02/10/2022

25/08/2022

Bluetongue
Multiple species
Bluetongue (BT) is an infectious, non-contagious, vector-borne viral disease that affects wild and domestic ruminants such as sheep, goats, cattle, buffaloes, deer, most species of African antelope and camels. Infection with bluetongue virus (BTV) is inapparent in the vast majority of animals but can cause fatal disease in a proportion of infected sheep, deer and wild ruminants. Insect vector of just a few species in the genus Culicoides transmit bluetongue virus (BTV) among susceptible ruminants, having become infected by feeding on viraemic animals. Twenty-six (26) different serotypes have been identified and the ability of each strain to cause disease varies considerably. There is no public health risk associated with BT, as the virus is not transmitted through contact with animals or wool, or through consumption of milk. Vaccination is used as the most effective and practical measure to minimize losses related to the disease and to potentially interrupt the cycle from infected animal to vector along with insect control measures.

10/08/2022

Bluetongue is an insect-borne viral disease to which all species of ruminants are susceptible, although sheep are most severely affected. Cattle and goats which appear healthy can carry high levels of the virus and provide a source of further infection.

04/08/2022

Clinical Signs
Bluetongue disease has two different manifestations—reproductive problems and acute vasculitis of several organ systems. With vasculitis, a spiking fever often precedes depression, anorexia, and rapid weight loss. Leukopenia is present. Affected animals may exhibit edema of the lips, tongue, throat, ears, and brisket. Other signs include excessive salivation and hyperemia or cyanosis of the oral mucosa, including the tongue (hence the name bluetongue). A common finding is a profuse serous nasal discharge that soon becomes mucopurulent, with crusting and excoriations apparent around the nose and muzzle. Oral lesions progress to petechial hemorrhages, erosions, and ulcers. Pulmonary edema often is severe, and pneumonia may develop. Skin lesions can pro-gress to localized dermatitis. Affected sheep may exhibit stiffness or lameness because of muscular changes and laminitis. Cyanosis or hemorrhagic changes of the skin of the coronet can extend into the h***y tissue. After recovery, a definite ridge in the horn of the hoof may be present for many months. In severe cases, the hoof sloughs. Mortality varies widely. In Africa, the virus is much more virulent than in the United States, and mortality rates range from 2% to 30%.
The reproductive or teratogenic form of the disease varies greatly with strain, host, and environmental factors. Teratogenic effects include abortions, stillbirths, and weak, live “dummy lambs.” Congenital defects may include hydranencephaly.

04/08/2022

Bluetongue is an insect-borne, viral disease primarily of sheep, occasionally goats and deer and, very rarely, cattle. The disease is non-contagious and is only transmitted by insect vectors. The disease is caused by a virus belonging to the family Reoviridae.
Primarily a disease of sheep but other species such as goats, cattle, buffaloes, camels, antelopes and deer can be infected. Humans are not affected.
The virus is present in most countries of Africa, the Middle East, India, China, the United States, and Mexico. Bluetongue virus infection, without associated clinical disease, is present in Southeast Asia, Papua New Guinea, northern South America and northern Australia. A strain of bluetongue virus was first identified in Australia in 1975 from trapped insects but despite its long-term presence, it has not caused any clinical disease.
The disease is characterised by fever, widespread haemorrhages of the oral and nasal tissue, excessive salivation, and nasal discharge. In acute cases the lips and tongue become swollen and this swelling may extend below the lower jaw. Lameness, due to swelling of the cuticle above the hoofs and emaciation, due to reduced feed consumption because of painful inflamed mouths, may also be symptoms of this disease. The blue tongue that gives the disease its name occurs only in small number of cases. Convalescence of surviving sheep is slow. The high fever in sheep results in wool breaks, which adds to production losses.
The virus cannot be transmitted between susceptible animals without the presence of the insect carriers. The incidence and geographical distribution of bluetongue depends on seasonal conditions, the presence of insect vectors, and the availability of the susceptible species of animals. The insect carriers, biting midges, prefer warm, moist conditions and are in their greatest numbers and most active after rains.

27/04/2022

Bluetongue is an insect-borne, viral disease affecting sheep, cattle, deer, goats and camelids (camels, llamas, alpacas, guanaco and vicuña). Although sheep are most severely affected, cattle are the main mammal reservoir of the virus and are critical in the disease epidemiology. The disease is non-contagious and is only transmitted by insect vectors (midges of the Culicoides species). The disease is caused by a virus belonging to the family Reoviridae. Bluetongue virus is a notifiable disease in many countries.
Species affected
BTV affects sheep, cattle, deer, goats and camelids (camels, llamas, alpacas, guanaco and vicuña). Humans are not affected.
Distribution
Historically, bluetongue virus has been confined to tropical and subtropical areas. However, endemic areas now exist in Africa, Europe, the Middle East, North and South America and Asia as well as on islands such as Australia, the South Pacific and the Caribbean. Multiple serotypes are found in many regions. Outbreaks can occur outside endemic areas, but in most cases, the virus does not persist once cold weather kills the Culicoides (midges) vectors.
More recently, climate change and trade patterns have seen increasing outbreaks in temperate regions (including Northern Europe) in recent years with outbreaks of up to 9 different serotypes occurring in Europe over the last 10 years. The most significant of which was the BTV-8 outbreak in Northern Europe in 2006-2008. Even more recently has been the circulation of BTV-8 in southern France in autumn 2017.
Bluetongue restricted zones in Europe as of the 18th of April 2018
Map: Bluetongue restricted zones in Europe as of the 18th of April 2018. For updated maps please click here
Key symptoms
Clinical signs are most apparent in sheep, where the disease is characterized by fever, widespread hemorrhages of the oral and nasal tissue, excessive salivation, and nasal discharge. In acute cases the lips and tongue become swollen and this swelling may extend below the lower jaw. Lameness, due to swelling of the cuticle above the hoofs and emaciation, due to reduced feed consumption because of painful inflamed mouths, may also be symptoms of this disease. The blue tongue that gives the disease its name occurs only in small number of cases. Convalescence of surviving sheep is slow. The high fever in sheep results in wool breaks, which adds to production losses.
Goats, cattle, and wild ruminants such as deer can appear healthy when infected. This can lead to silent spread by midges feeding on the infected animals.
Spread
The virus cannot be transmitted between susceptible animals without the presence of the insect carriers. The incidence and geographical distribution of bluetongue depends on seasonal conditions, the presence of insect vectors, and the availability of the susceptible species of animals. The insect carriers, biting midges, prefer warm, moist conditions and are in their greatest numbers and most active after rains.
The virus
Bluetongue virus does not survive outside the insect vectors or susceptible hosts. Animal carcasses and products such as meat and wool are not a method of spread. Survival of the virus within a location is dependent on whether the vector can overwinter in that area.
At least 26 different serotypes of the bluetongue virus have been identified (with potential for still more to be discovered). The BTV genome evolves rapidly via mutations. Some virus variants may be selected as they are better adapted to the environmental conditions. This evolution and selection of variants during the transmission of BTV between susceptible animals and vector (midges) appear to be the main mechanism that leads to the genetic diversity amongst BTV field strains.
Disease control measures
The strategy is to contain the outbreak and minimize trade impact. Activities include:
Restriction of movement of animals if BTV is suspected
Confirmation of suspected cases by laboratory tests
Zoning to define infected and disease-free areas
Vaccination of susceptible animals
Surveillance to determine the extent of virus and vector distribution
Vector surveillance and control strategies
See e.g. GB Bluetongue Virus Disease Control Strategy (Defra) There is no justification for stamping out but some animals may need to be destroyed for welfare reasons. It is not possible to eradicate the bluetongue vectors.
Diagnostics
If you suspect BTV in your herd, the first step is to contact your veterinarian. The next step is to work with your veterinarian to obtain blood samples from animals for diagnostic testing to confirm whether the animals are infected with BTV. At least 26 different serotypes of BTV have been identified (with potential for still more to be discovered), therefore it is important to have a single test that can detect any of these viruses. If BTV is verified, the next step is to serotype the strain to apply the appropriate vaccine.
Real-time polymerase chain reaction (qPCR) detection tools can quickly and reliably identify whether BTV is present in the herd and identify specific genotypes.
Virus diversity needs to be closely monitored and diagnostic test tools’ capabilities regularly tested to detect new variants. Here, the collaboration with national reference institutes is required to regularly monitor virus sequences and update diagnostic tools if needed.
For more information about BTV diagnostic tools visit the Thermo Fisher Scientific website.
Many countries are establishing surveillance and management programmes to help veterinarians and farmers battle BTV when detected. As always, remain vigilant monitoring for BTV in your herd, especially in warm, humid weather conditions.

27/04/2022

Advice for farmers
Bluetongue does not pose a threat to human health or food safety, but can have a negative impact on farm incomes, for example by causing reduced milk yield in cows and infertility in sheep.
Farmers must be vigilant when importing livestock from high risk or restricted areas, and perhaps even reconsider importing animals from areas where BTV is present. If imports are required farmers must consider pre-export testing consignments of animals imported from BTV affected areas. Farmers are urged to seek advice from their vet about the risks and the health status of animals they'd like to import, prior to importing them. When importing animals, farmers should make sure that the animals have the correct paperwork confirming they've been vaccinated against the right strain/s of bluetongue.
The UK has robust disease surveillance procedures and continue to carefully monitor the situation in France, where Bluetongue disease control measures are in place.
The latest assessment shows the risk of outbreak in the UK is currently low, but the detection of further BTV-4 and BTV-8 in France and BTV-8 in Belgium and Germany is a reminder for farmers to remain vigilant for disease and report any suspicions to the Animal and Plant Health Agency.
The impact of bluetongue on a farm business
Hear from Ken Proctor, he had Bluetongue on his dairy farm back in 2008, read about his experience, the short and longer term losses that his herd suffered and why the disease must not be treated with complacency.
An outbreak of bluetongue will affect farm incomes directly and indirectly. In addition to direct costs for treatment, loss of production, the necessary imposition of animal movement restrictions during a bluetongue outbreak might have an even greater negative impact on a farm business.
The current bluetongue disease control strategy imposes a control zone (CZ) of at least 20km around an infected premises (IP). No animal movements are permitted within the control zone.
At the same time, a restriction zone, consisting of a protection zone (PZ) and surveillance zone (SZ) is declared. The minimum size of the PZ is 100km and the SZ 150km from the infected premises.
Animals are free to move into the PZ and SZ from zone free areas, but are not then allowed to move out of the zones unless they have been effectively vaccinated at least 60 days previously, or have developed natural full immunity to the BTV serotype circulating. Any such moves maybe be subject to compliance with Government licensing requirements.
Movement within a zone is allowed, assuming that an animal does not show clinical signs of disease on the day of movement. Movement is allowed from the SZ into the PZ, but not from the PZ into the SZ unless certain criteria are fulfilled. Farmers on the border of these zones may also find their business disrupted
The zones may be expanded beyond their minimum, but this decision will only be taken in light of the specific outbreak situation and will be influenced by the rate of spread, time of year (vector activity) and other veterinary and commercial factors.
It is therefore very important, that any farmers who rely on long distance movements of their stock as part of their business model should consider vaccination as a sensible precaution, since if they find their farm premises located in a zone or part of a zone, there could be implications for their ability to trade.
Vaccination
Vaccination remains a proven technique for the prevention and control of Bluetongue and keepers are advised to speak to their private vet.
Although vaccine is not currently available in the UK, where there is a justifiable need, vaccine may be imported from mainland Europe on a case by case basis through a special import licence. Vets can apply to the Veterinary Medicines Directorate for a Special Import Certificate (SIC), therefore, farmers need to talk to their vet about vaccination if this is something they are considering.
The certificate allows keepers to import safe and effective bluetongue vaccine directly from the EU to vaccinate their stock.
If there is wide demand then vaccine manufacturers may again be persuaded to provide vaccine direct to the UK market.
Importing livestock from restricted areas
Farmers are urged to carefully consider whether or not to import animals into the UK from a restricted area, if a farmer does wish to import animals they should:
Make sure that animals have the correct paperwork confirming they’ve been vaccinated against the right strains of bluetongue - this will depend on which country they’re importing from
Consider what additional guarantees the seller can provide - such as a pre-export test to prove immunity to BTV
Consider pre-vaccinating their flock or herd against the relevant strains of bluetongue before introducing new animals
What you can do now
Monitor stock carefully and report any clinical signs of disease. Your local vet can provide help in the diagnosis.
Source animals responsibly and check the health status of animals you are looking to buy.
Maintain good biosecurity such as washing equipment after use.
Consider vaccination as the only effective means of protecting susceptible animals from BTV. You are advised to contact a vet about the benefits and availability of a vaccine.
What to do if you suspect disease
If you suspect bluetongue you must report it immediately to the Animal and Plant Health Agency (APHA).

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Bluetongue and Lumpy skin disease – awareness and prevention

Clinical Signs Bluetongue disease has two different manifestations—reproductive problems and acute vasculitis of several organ systems. With vasculitis, a spiking fever often precedes depression, anorexia, and rapid weight loss. Leukopenia is present. Affected animals may exhibit edema of the lips, tongue, throat, ears, and brisket. Other signs include excessive salivation and hyperemia or cyanosis of the oral mucosa, including the tongue (hence the name bluetongue). A common finding is a profuse serous nasal discharge that soon becomes mucopurulent, with crusting and excoriations apparent around the nose and muzzle. Oral lesions progress to petechial hemorrhages, erosions, and ulcers. Pulmonary edema often is severe, and pneumonia may develop. Skin lesions can pro-gress to localized dermatitis. Affected sheep may exhibit stiffness or lameness because of muscular changes and laminitis. Cyanosis or hemorrhagic changes of the skin of the coronet can extend into the horny tissue. After recovery, a definite ridge in the horn of the hoof may be present for many months. In severe cases, the hoof sloughs. Mortality varies widely. In Africa, the virus is much more virulent than in the United States, and mortality rates range from 2% to 30%. The reproductive or teratogenic form of the disease varies greatly with strain, host, and environmental factors. Teratogenic effects include abortions, stillbirths, and weak, live “dummy lambs.” Congenital defects may include hydranencephaly.

Bluetongue virus of ruminants Bluetongue disease (initially known as ‘malarial catarrhal fever’) was first observed in the late eighteenth century in sheep, goats, cattle, and other domestic animals, as well as in wild ruminants (e.g., white-tailed deer, elk, and pronghorn antelope) in Africa. A distinctive lesion in the mouths of the infected animals with severely affected, dark blue tongues was a characteristic symptom. That the disease was caused by a filterable agent was discovered in 1905. The first confirmed outbreak outside of Africa occurred in sheep in Cyprus in 1924 and this was followed by a major outbreak in 1943–44 with 70% mortality. The disease was recognized subsequently in the USA in 1948 and in Southern Europe in 1956 where approximately 75% of the affected animals died. The outbreaks of bluetongue disease in the Middle East, Asia, Southern Europe, and the USA in the early 1940s and 1950s led to its subsequent description as an ‘emerging disease’. To date, based on serum-neutralization tests, 24 different serotypes have been isolated in tropical, semitropical, and temperate zones of the world including Africa, North and South America, Australia, Southeast Asia, the Middle East, and, more recently, Southern and Central Europe. An important factor in the distribution of bluetongue virus (BTV) worldwide is the availability of suitable vectors, usually biting midges (gnats) of the genus Culicoides.

Bluetongue is an insect-borne, viral disease primarily of sheep, occasionally goats and deer and, very rarely, cattle. The disease is non-contagious and is only transmitted by insect vectors. The disease is caused by a virus belonging to the family Reoviridae. Primarily a disease of sheep but other species such as goats, cattle, buffaloes, camels, antelopes and deer can be infected. Humans are not affected. The virus is present in most countries of Africa, the Middle East, India, China, the United States, and Mexico. Bluetongue virus infection, without associated clinical disease, is present in Southeast Asia, Papua New Guinea, northern South America and northern Australia. A strain of bluetongue virus was first identified in Australia in 1975 from trapped insects but despite its long-term presence, it has not caused any clinical disease. The disease is characterised by fever, widespread haemorrhages of the oral and nasal tissue, excessive salivation, and nasal discharge. In acute cases the lips and tongue become swollen and this swelling may extend below the lower jaw. Lameness, due to swelling of the cuticle above the hoofs and emaciation, due to reduced feed consumption because of painful inflamed mouths, may also be symptoms of this disease. The blue tongue that gives the disease its name occurs only in small number of cases. Convalescence of surviving sheep is slow. The high fever in sheep results in wool breaks, which adds to production losses. The virus cannot be transmitted between susceptible animals without the presence of the insect carriers. The incidence and geographical distribution of bluetongue depends on seasonal conditions, the presence of insect vectors, and the availability of the susceptible species of animals. The insect carriers, biting midges, prefer warm, moist conditions and are in their greatest numbers and most active after rains.