Bluetongue is an animal disease affecting domestic and wild ruminants including sheep, cattle, goats and deer. It is a non-contagious infection transmitted by flying midge insects belonging to the Culicoides genus. 24 serotypes of the virus are currently known to science, each of which can have differing virulence and mortality rates. The way it can be transmitted and the susceptible species are continually being investigated by scientists.
Bluetongue is not known to be harmful to humans. However, it can cause considerable damage to livestock populations. It is a trans-boundary disease and the epidemiological situation in one country can affect neighbouring ones, while national measures tend not to be sufficient to control its spread.
The central role of flying insects in Bluetongue epidemiology means that the prevalence of the disease is governed by ecological factors that favour insect survival such as temperature, humidity and soil characteristics. Bluetongue outbreaks generally occur seasonally and in warm climates.
Until recently Bluetongue had only been recorded in southern regions of the EU including parts of Italy, Spain, France and Portugal. In August 2006 several Northern European countries reported the first ever outbreaks of Bluetongue, including in Holland, Belgium, Germany and France. Further outbreaks were reported in 2007 and 2008 including in the UK and Sweden.
EU control measures to combat Bluetongue are in place since the year 2000 through Council Directive 2000/75/EC, including the establishment of protection and surveillance zones and a ban on susceptible animal species leaving those zones. Further control rules have been adopted to tackle the recent outbreak through coordinated European action. They are informed by EFSA’s scientific advice and are decided on by the European Commission and EU Member States. Commission Regulation (EC) No 1266/2007 contains detailed implementing rules for the control, monitoring, surveillance of animals and flying midge insects plus restrictions on the movement of certain animal species. Details on the restriction zones in EU Member States are made available by the European Commission.
Vaccination against Bluetongue is an important tool for the control of the disease and is also used to permit ‘safe’ trade in live ruminants based on EU legislation and in accordance with World organisation for animal health (OIE) standards.
EFSA’s role and activities
EFSA provides scientific support on Bluetongue to the European Commission, European Parliament and the Member States. As the recent Bluetongue outbreak is a newly emerging and ongoing risk issue affecting many regions of the EU, EFSA has a key role in working with Member States to monitor the evolving situation closely and ensure the latest scientific advice is available to risk managers.
EFSA’s activities focus on increasing scientific understanding of the dynamics and spreading patterns of the disease in Europe, and on providing a scientific basis for integrated risk management measures.
Part of EFSA’s role involves networking actively with Member States and EU institutions in the collection, sharing and updating of the latest scientific data on Bluetongue. Shortly after the first outbreaks in Northern Europe, EFSA published a scientific note in September 2006 to launch this activity, asking Member States to work closely with EFSA to collect information and share national risk assessments on recent outbreaks.
In 2007 EFSA provided regular weekly reports on the disease situation and an epidemiological analysis of surveillance data from ongoing outbreaks, in order to characterise the epidemic that started in August 2006 and to conduct modeling of future scenarios. Rapid access to animal population databases at national level is a key factor allowing such epidemiological analyses to be carried out promptly. EFSA co-ordinated an epidemiological working group involving experts from affected countries. The report of the global epidemiological analysis of the Northern European outbreak was issued in April 2007. It covered the origin, clinical signs, and spread of the disease. Wind had a great impact on disease spread. This allowed EFSA to make an accurate prediction of the area in the UK where the disease would most likely occur in 2007.
Scientific advice and recommendations
The epidemiological work supported the conclusions of EFSA’s Panel on animal health and welfare (AHAW Panel), that continues to provide scientific opinions on the disease based on mandates from the European Commission and self-task activities. They focus on issues such as:
- The origins and occurrence of exotic Bluetongue serotypes in the EU, to improve understanding of the possible future spread of the disease.
- The epidemiology and clinical diagnosis of different Bluetongue strains.
- The precise role of flying insects in spreading the disease, including their seasonal activity patterns and flight ranges.
- The suitability of means to control the insects involved in spreading Bluetongue, such as insecticides, repellents and other ways of protecting animals from insect bites for instance using animal housing.
- The use of vaccines to reduce the risk of infection and their effectiveness, based on experience in EU Member States and elsewhere in the world.
- The risks of disease transmission during animal transit when animals are transported from or through restricted zones within the EU, including the effectiveness of using insecticide or repellents in vehicles.
Among its recommendations, EFSA maintains that the use of vaccines (preferably inactivated) is a priority and that measures to stimulate the development of these vaccines should be encouraged. The approval of such vaccines is within the remit of the European Medicines Agency (EMEA).
Based on developments in the epidemiology of Bluetongue in Europe and changes in climatic conditions, EFSA has recommended the use of effective insecticides and other preventive measures at ports of entry into Europe and during trade of animals between infected and Bluetongue-free areas of Europe.
EFSA has stressed the need to carry out surveillance of vectors not only for Bluetongue but also for other possible emerging animal diseases. While research funding is in the remit of the European Commission’s DG Research, EFSA has launched a collaborative project on three such diseases which will include the evaluation of the distribution of arthropod vectors in the EU and their potential role in transmitting exotic or emerging vector-borne diseases and zoonoses. This report should be available in the second half of 2008.