title: Quantitative assessment of the probability of bluetongue virus overwintering by horizontal transmission: application to Germany.
abstract: Even though bluetongue virus (BTV) transmission is apparently interrupted during winter, bluetongue outbreaks often reappear in the next season (overwintering). Several mechanisms for BTV overwintering have been proposed, but to date, their relative importance remain unclear. In order to assess the probability of BTV overwintering by persistence in adult vectors, ruminants (through prolonged viraemia) or a combination of both, a quantitative risk assessment model was developed. Furthermore, the model allowed the role played by the residual number of vectors present during winter to be examined, and the effect of a proportion of Culicoides living inside buildings (endophilic behaviour) to be explored. The model was then applied to a real scenario: overwintering in Germany between 2006 and 2007. The results showed that the limited number of vectors active during winter seemed to allow the transmission of BTV during this period, and that while transmission was favoured by the endophilic behaviour of some Culicoides, its effect was limited. Even though transmission was possible, the likelihood of BTV overwintering by the mechanisms studied seemed too low to explain the observed re-emergence of the disease. Therefore, other overwintering mechanisms not considered in the model are likely to have played a significant role in BTV overwintering in Germany between 2006 and 2007.
authors.affiliation: Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autónoma de Barcelona, 08193 Bellaterra, Barcelona, Spain. sebastian.napp@cresa.uab.es.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Napp
authors.forename: Simon
authors.initials: S
authors.lastname: Gubbins
authors.forename: Paolo
authors.initials: P
authors.lastname: Calistri
authors.forename: Alberto
authors.initials: A
authors.lastname: Allepuz
authors.forename: Anna
authors.initials: A
authors.lastname: Alba
authors.forename: Ignacio
authors.initials: I
authors.lastname: García-Bocanegra
authors.forename: Armando
authors.initials: A
authors.lastname: Giovannini
authors.forename: Jordi
authors.initials: J
authors.lastname: Casal
mesh_terms: D000818:Animals; D001819:Bluetongue / Q000453:epidemiology / Q000635:transmission* / Q000821:virology; D001820:Bluetongue virus / Q000502:physiology*; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000635:transmission* / Q000821:virology; D002519:Ceratopogonidae / Q000821:virology*; D004196:Disease Outbreaks / Q000662:veterinary*; D005858:Germany / Q000453:epidemiology; D006799:Housing, Animal; D007303:Insect Vectors / Q000821:virology*; D008954:Models, Biological; D011336:Probability; D018570:Risk Assessment; D012621:Seasons; D012756:Sheep; D013269:Stochastic Processes