Bluetongue - an ever present threat to UK ruminants?

In September 2007 bluetongue virus (BTV), a vector-borne virus of ruminants, reached the UK for the first time in recorded history following the incursion and sustained spread of a BTV-8 strain in Northern Europe. In the last 20 years multiple incursions of different BTV strains into Europe have changed the landscape and perception of the threat of arthropod-borne viruses (arboviruses) to livestock in temperate climate regions. The clinical and economic consequences of the BTV-8 epidemic throughout Northern Europe during 2006-2009 have been far more damaging to the farming sector than originally imagined, especially for those countries at the centre of the outbreak e.g. Netherlands, Belgium, Germany and France: Although mass vaccination of ruminants allowed Northern European countries to regain their bluetongue free status, new incursions of other BTV strains still occurred into Southern and Eastern Europe. In 2015 French authorities announced the re-emergence of the BTV-8 strain in mainland France, while at the same time a BTV-4 strain spread through Eastern Europe as far north as Austria. The recent events of further bluetongue outbreaks in Northern Europe seem to highlight that BTV, and possibly other arboviruses, now pose a continuous risk to livestock even in temperate climate zones. In this paper the clinical, ecological and epidemiological features of BTV and future implications for the UK ruminant livestock sector will be reviewed.