Among domestic animals, clinical disease occurs most often in sheep, and can result in significant morbidity. Bluetongue has been recognized as a specific disease of sheep since the commencement of the sheep breeding industry in the early days of the colonization of the cape colony. Bluetongue is a noncontagious, infectious viral disease of domestic and wild ruminants. Although bluetongue virus is present in a monitored zone across northern australia, bluetongue disease has never been reported in australia. Bluetongue is a viral disease affecting sheep, cattle, deer, goats and camelids camels, llamas, alpacas, guanaco and vicuna. Severe disease can also occur in wild ruminants, such as whitetailed deer, pronghorn, and desert bighorn sheep.
The idexx bluetongue competition ab test detects antibodies specific to the bluetongue virus btv in individual sheep, goat and cattle sera. Bluetongue virus btv does not infect humans and, consequently, the disease has no. Bluetongue virus can infect all ruminants but it usually only causes serious disease in sheep. Lambs typically become infected when they swallow water, milk or feed that has been contaminated by manure from infected animals. Nadis animal health skills bluetongue in cattle and sheep. Indirect elisa o shown to be reliable and useful for surveillance purposes for bulk milk samples for more detailed information regarding laboratory diagnostic methodologies, please refer to chapter 2. Initially, the disease was reported in sheep in south africa in 1881 and it was ascribed as epizootic catarrh. Bluetongue is a viral disease of ruminants eg cattle, sheep goats, deer and is primarily transmitted by midges culicoides species. Bluetongue is a noncontagious, viral disease spread by biting insects. View enhanced pdf access article on wiley online library html view download pdf for offline viewing. The epidemiology of bluetongue virus infection is poorly defined in many parts of the world, including a wide.
It is caused by the bluetongue virus btv and is placed in the office international des epizooties list of diseases. Neitz, section of protozoology and virus diseases, onderstepoort. The confirmation of bluetongue virus serotype 8 btv8 in the netherlands on august 17, 2006 marked the onset of the first outbreak of bluetongue in northwest europe. Bluetongue outbreaks have been reported rarely, involving only a relatively few animals and usually affecting imported european breeds of sheep. Bluetongue virus btv is an economically important orbivirus of the reoviridae family, causes a haemorrhagic disease mainly in sheep and occasionally in cattle and some species of deer. This is acute infectious but not contagious disease of sheep characterized by fever, inflammation and ulceration of buccal mucosa and tongue. Despite the normally low mortality rate of bluetongue disease, susceptible breeds of sheep in africa face much higher mortality rates. Bluetongue virus is the typespecies of the genus orbivirus in the family reoviridae. Outbreaks of bluetongue in cyprus in 1943 caused between 60 and 70% losses in some flocks. The severity of disease is influenced by factors such as the virulence of the bluetongue strain, the livestock breed and individual susceptibility. An insect vector spreads the virus and it only occurs where the vector is present. Although sheep are most severely affected, cattle are the main mammal reservoir of the virus and are critical in the disease epidemiology.
Wildlife notebook series alaska department of fish. Affected animals can have a slight to severe blue discolouration of the. A study of the role of cellmediated immunity in bluetongue virus infection in sheep, using cellular adoptive transfer techniques. However, they can become dangerous especially when.
The bluetongue situation in the eu has changed in recent times with incursions of new serotypes. Bluetongue bt and epizootic hemorrhagic disease ehd are similar viral diseases spread by biting gnats which results in similar clinical signs in cattle, sheep and whitetail deer. Differential diagnosis of bluetongue in cattle and sheep. Bluetongue in sheep and cattle was first described in the late 18th century. Dall sheep are found in relatively dry country and frequent a special combination of open. Diagnosis, prevention and control of blue tongue in sheep. National sheep association is an organisation which represents the views and interests of sheep producers throughout the uk. Bluetongue is usually a much more serious disease in sheep than in cattle. Although sheep are most severely affected, cattle are the main mammalian reservoir of the virus and are very important in the epidemiology of the disease. Bluetongue disease an overview sciencedirect topics. Pdf investigation of bluetongue in sheep in western iran. Bluetongue was first described in south africa where it was likely endemic in wild ruminants.
Nsa is funded by its membership of sheep farmers and it activities involve it in every aspect of the sheep industry. Pdf diagnosis, prevention and control of blue tongue in. Pdf epidemiological investigation of bluetongue virus. Get a printable copy pdf file of the complete article 907k, or click on a page image below to browse page by page. These diseases were first noted in south africa in the late 1800s and have since spread over much of the world where conditions. The control of bluetongue disease relies essentially on vaccination. The aim of this study was to describe the seroprevalence. Before 1998, bt was considered an exotic disease in europe. Bluetongue bt disease is not a major animal health problem in the countries to the east and southeast of the indian subcontinent. Blue tongue is an insectborne, viral, noncontagious disease that occurs in some areas of new mexico. Bluetongue virus can replicate in many species of ruminants, often asymptomatically. The virus is transmitted by the midges culicoides imicola, culicoides variipennis, and. Bovine viral diarrhea in captive rocky mountain bighorn. Following vaccination, at least 14 of 28 50% vaccinated bighorn sheep developed hemorrhagic diarrhea, and 6 of 28 21% vaccinated bighorn sheep died.
Sheep flocks with high rates of infection may lose up to 10 percent of their adult ewes due to wasting loss of body condition. Bluetongue can be a severe disease in sheep with mortality varying from 580% depending on the virus serotype and on the immune status of the sheep populations. Bluetongue epidemiology in the european union volume 14. Bluetongue informationleaflet forveterinarypractitioners.
Affected sheep may have erosions and ulcerations on the mucous membranes, dyspnea, or lameness from muscle necrosis and inflammation of the coronary band. Bluetongue virus affects many domestic and wild ruminants. There is still disagreement as to the extent of the clinical effects of bt in cattle. The incursion of btv8 into europe was preceded by epizootics of. In october 2008, a 15yearold female alpaca vicugna pacos housed at a breeding farm in. In late summer 2017, we observed acute, fatal cases of bovine viral diarrhea in captive rocky mountain bighorn sheep ovis canadensis canadensis in colorado following use of a contaminated modifiedlive bluetongue virus vaccine. Bluetongue bluetongue virus can infect all ruminants, although clinical disease in endemic regions is mainly associated with certain breeds of sheep, while cattle remain subclinically infected. If possible, keep sheep separate from cattle and wild game. Dall sheep ovis dalli dalli inhabit the mountain ranges of alaska. Common diseases and health problems in sheep and goats.
Bluetongue disease is an insectborne multiserotype viral disease affecting sheeps, cattles, goats and other ruminants. Bluetongue virus is known to be present in southern europe, serotypes 1, 2, 4 and 16 have all been. Bluetongue bt is an arthropodtransmitted viral disease of nonafrican ungulates, principally sheep. Sheep are large domestic animals that are normally docile. Control dont graze sheep in wet lowlying areas where the midge is present.
The virus was originally collected in 1981 in the blood of a sheep with bt and had been previously passaged twice in sheep, thus the blood inoculum was from the second sheep passage. There is no treatment against the blue tongue virus, but antibiotics will treat secondary bacterial infections. It affects species of ruminants, particularly sheep. Experimental reproduction of severe bluetongue in sheep. Bluetongue causes many different symptoms in affected animals, including ulcers, sores, painful hooves, lameness and reproductive problems. Blue tongue is a noncontagious, infectious, arthropodborne viral disease of sheep, goat, cattle and deer, with a worldwide distribution. Cattle may be infected with the virus but rarely show disease. Veterinary research institute, onderstepoort, south africa. Review beyan amin, abdu moham med and kula jilo school of veterinary medicine, colleg e of agriculture and veterinary medicine. Fatal bluetongue virus infection in an alpaca vicugna. Bluetongue is an insectborne viral disease of ruminants.
A closely related virus causes epizootic hemorrhagic disease ehd in deer. This disease mostly affects sheep and goat and cattle are very rarely affected. Sheep with lesions in the mouth and esophagus may vomit and this may lead to aspiration of the ruminal contents, pneumonia and death. From 1998 through 2005, at least 6 bt virus strains belonging to 5 serotypes btv1, btv2, btv4, btv9, and btv16 were continuously present in the mediterranean basin. Btv orbivirus, reoviridae is a vectorborne, doublestranded rna virus with 24 known serotypes, which causes a noncontagious infectious disease in ruminants. Bluetongue is an infectious, noncontagious disease of ruminants and camelids transmitted by culicoides biting midges. While all symptoms usually develop within a month, the incubation period is 520 days. It was first recognized in south africa in the early 1930s after the introduction of european breeds. Clinical cases tend to occur mainly in sheep, but cattle, goats. It is transmitted from infected animals to susceptible sheep by the bites of a small insect commonly referred to as a gnat. The disease results from vascular injury analogous to that of human haemorrhagic viral fevers. The manifestations of bluetongue range from an inapparent to a fatal outcome depending on the. Bluetongue bt is a reportable disease of considerable socioeconomic concern and of major importance in the international trade of animals and animal products. The fatality rate is very high for this virus in deer but its effects on cattle and sheep are relatively mild.
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