IFAH Statement on Bluetongue

Bluetongue is a viral disease that affects ruminants, especially sheep.  It can also affect cattle, goats, camels and wild ruminants. It has been named after one of the symptoms that can occur in infected animals particularly sheep, which is a bluish coloration of the tongue.  

Bluetongue does not infect people, nor is there any risk of the disease being contracted or spread through meat or milk.

Sheep are particularly susceptible to the disease, with diverse symptoms. Some sheep become seriously ill and die, while others exhibit hardly any symptom at all. In most cases the first symptom is high fever, followed by swelling and pain in and around the mouth, which in turn causes excessive salivation. The tongue may be ulcerated and develop a swollen, purple colour due to cyanosis (lack of oxygen), hence the name bluetongue.

Infected cattle normally develop milder if any symptoms. However, productivity and reproduction can be severely affected. Other ruminants generally display milder symptoms.

Ruminants cannot directly infect one another. The bluetongue virus is transmitted exclusively by a very small insect (midge – Culicoides species), which passes the virus by first biting an infected animal before biting an uninfected one.

At present 24 types (serotypes) of the virus have been identified. The virulence and mortality rate of the different virus strains vary considerably.

An newly emerging disease distribution pattern

Globally, the bluetongue disease has until recently been distributed between latitudes of approximately 50° north and 34° south, but is known to be expanding into the northern hemisphere.  

In the last two years Europe, particularly, witnessed an unexpected spread of the disease: Before 2006, bluetongue had been confirmed in sheep flocks in the Balearic Islands, Corsica, Sardinia, Sicily, other parts of Italy, Spain, France and Portugal. 

Since 2006 Northern Europe has been affected by serotype 8, a new virus type in the continent, which spread significantly in 2007. As from 25 March 2008, the restriction zone covers Austria, Belgium, the Czech Republic, Denmark, France, Germany, Luxemburg, the Netherlands, Poland, the United Kingdom and Switzerland.

 
Development of vaccines against bluetongue

While it has proven impossible to eradicate disease-carrying midges, vaccination against bluetongue has been successful in combating the disease.  Several animal health companies have developed vaccines against various virus types, including serotype 8.

It normally takes 5 to 7 years to develop a new or improved vaccine serotype. IFAH and its members are striving to shorten the process and so increase the availability of vaccines against new disease serotypes.

The animal health industry is of the view that a clear strategy by the responsible authorities on bluetongue vaccination is necessary and is willing to support them and other stakeholders in its implementation.  This should encompass predictability and timely planning, as industry needs to know the demand envisaged by national vaccination programmes to ensure the sufficient supply of bluetongue vaccine doses on time. 

Long term, it is important for all stakeholders, including the authorities and the vaccine industry to work together to prepare for emerging diseases. One such initiative is the European Technology Platform for Global Animal Health (ETPGAH), a stakeholder-led initiative chaired by IFAH-Europe, which is working on disease prediction.

The platform is currently setting up a disease information database with the aim to analyse gaps in the ability to control disease and a better coordination of research on vaccine development.

March 2008