Report on Epidemiological analysis of the 2006 bluetongue virus serotype 8 epidemic in north-western Europe
Last updated: 4 June 2007
Publication Date: 4 April 2007
Bluetongue (BT) is an arthropod-borne viral disease of domestic and wild ruminants, affecting particularly certain breeds of sheep with severe clinical disease, including mortality. On 14 August 2006, a private veterinary practitioner in the southern province of Limburg, in The Netherlands, notified the veterinary authorities of BT-suspect cases on four different holdings in that Member State (MS) These were the first suspicions of a rapidly-spreading BT virus (BTV)-epidemic in north-western Europe, which has since affected cattle and sheep holdings in Belgium, Germany, France, Luxembourg, and The Netherlands. On 28 August 2006, the CRL in Pirbright announced that BTV-serotype 8 (BTV-8) was causing the outbreaks.
The provisional results, to be delivered by 31 January 2007, were presented to the BTV-8WG on the 6th of February 2007 and to the European Commission and Chief Veterinary Officers (CVOs) at an EC meeting on the 7th of February 2007 in Brussels. Taking into account the feedback from the meetings on the 6th and the 7th of February 2007 the reports were then revised. For the final report additional data through 31 January 2007 were considered as well, where relevant.
4. The BTV-8 virus was found to be present in vectors (Culicoides species) which are endemic to north-western Europe. C. imicola, which is thought to be responsible for at least 90% of BTV transmission in the Mediterranean Basin, was not found amongst a total of approximately 100,000 Culicoides collected in the infected MS. This demonstrates that species endemic to the palaearctic region are capable of transmitting BTV and – judging from the rapid spread of the virus – no pre-adaptive phase was required in the indigenous Culicoides. Species found to be PCR-positive were C. dewulfi (a species breeding exclusively in the dung of cattle and horses) and C. obsoletus / C. scoticus.
The movement of cattle mainly occurred in a north-western direction and the extension of the epidemic to the east can therefore not be explained by these transports.