title: Seasonal spread and control of Bluetongue in cattle.
abstract: Bluetongue is a seasonal midge-borne disease of ruminants with economic consequences on herd productivity and animal trade. Recently, two new modes of transmission have been demonstrated in cattle for Bluetongue virus serotype 8 (BTV8): vertical and pseudo-vertical transmission. Our objective was to model the seasonal spread of BTV8 over several years in a homogeneous population of cattle, and to evaluate the effectiveness of vaccination strategies. We built a deterministic mathematical model accounting for the seasonality in vector abundance and all the modes of transmission. We proposed a counterpart of the basic reproduction number (R(0)) in a seasonal context (R(S)). Set A(t) is the number of secondary cases produced by a primary case introduced at time t. R(S) is the average of A(t). It is a function of midge abundance and vaccination strategy. We also used A*, the maximum of A(t), as an indicator of the risk of an epidemic. Without vaccination, the model predicted a large first epidemic peak followed by smaller annual peaks if R(S)>1. When R(S)<1, small epidemics could occur if A* >1. Vaccination reduced R(S) and A* to less than one, but almost perfect vaccine efficacy and coverage were required to ensure no epidemics occurred. However, a lower coverage resulting in R(S)>1 could decrease infection prevalence. A further step would be to optimize vaccination strategies by targeting an appropriate period of the year to implement the vaccination.
authors.affiliation: INRA, UMR1300 Bio-agression, Epidémiologie et Analyse de Risque, BP 40706, F-44307 Nantes, France. maud.charron@oniris-nantes.fr
authors.forename: Maud V P
authors.initials: MV
authors.lastname: Charron
authors.forename: Henri
authors.initials: H
authors.lastname: Seegers
authors.forename: Michel
authors.initials: M
authors.lastname: Langlais
authors.forename: Pauline
authors.initials: P
authors.lastname: Ezanno
mesh_terms: D000818:Animals; D001819:Bluetongue / Q000453:epidemiology / Q000517:prevention & control / Q000635:transmission*; D001820:Bluetongue virus / Q000145:classification / Q000276:immunology / Q000302:isolation & purification; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000517:prevention & control* / Q000821:virology; D002519:Ceratopogonidae / Q000821:virology; D058872:Epidemics; D007303:Insect Vectors / Q000821:virology; D008954:Models, Biological; D012621:Seasons; D014611:Vaccination; D014765:Viral Vaccines
chemical_list: D014765:Viral Vaccines