Bluetongue (BT) is a disease in ruminants caused by an Orbivirus that is transmitted by midges. There are at least 24 serotypes of Bluetongue virus (BTV).

Infected midges naturally infect domestic and wild ruminants (for example, sheep, cattle, goats and deer) and camelids (for example, llama and alpaca) by bites during feeding. Cattle show higher and longer viraemia than sheep, but the disease is seen more frequently and more severe in sheep (depending on the serotype of BTV). The disease is characterized by inflammation of the mucus membranes around the mouth and nose, this inflammation causes the rarely seen 'blue tongue' that gives the disease its name.   

In Europe, BTV-spread was formerly associated to the presence of Culicoides imicola. In 2006 it became clear that BTV could also be spread by endemic species of Culicoides in Northern parts of Europe. Bluetongue does not affect humans so there are no public health implications.

More information:

Disease facts: Bluetongue (IAH)

Disease facts: Bluetongue (DEFRA)

Publications and factsheets: Bluetongue (DEFRA)

Technical disease cards OIE

EPIZONE and bluetongue


  • Numerous activities for harmonization and standardization of real time RT-PCR assays for BTV
  • A list could define of validated, functional real-time RT-PCR assays useful for the sensitive, specific and robust detection of BTV based on information of collected data has been compiled and summarized in a review article.
  • Ring trial results for BTV. As the most useful tool to improve the standardization and harmonization of the real-time PCR diagnostics the realization of ring trials was favoured.
  • Bluetongue virus (BTV) serotype 8 ELISA tests have been designed, in collaboration with ID-VET (Philippe POURQUIER).

  Intervention Strategies

  • A discussion group on bluetongue disease has been established in which experts from both outside and inside EPIZONE were invited to participate. Information on research activities is collected and a plan for future joint activities prepared.  
  • Bluetongue virus (BTV) is used for the in vitro and in vivo infection experiments. A better knowledge of the functional states (cytokines, chemokines, co-stimulatory molecules etc.) of antigen presenting cells and the influence caused by epizootic diseases will improve the design of vaccine formulation and will provide the basis for a better and more rational use of adjuvants and immunomodulators.

  Surveillance and Epidemiology

  • Molecular epidemiology is studying genetic relationships between pathogens, bluetongue and also bacterial and mycoplasmal diseases such as e.g. contagious bovine pleuropneumonia. To support this, two web-based molecular epidemiology servers are being developed.

 Risk Assessment 

  • Experts are consulted to identify and prioritize potential disease threats to Europe as a result of changing environments. An expert opinion workshop was held where a questionnaire based on a qualitative risk assessment framework was used to obtain data to assess the impact of climate change on the risks of incursion of vector-borne livestock viruses into the EU. The results of the expert opinion workshop allow predictions on emerging animal diseases in the next decades.
  • A first stage of implementation of a definition of a standardized data set was completed

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