Fig. 1

Timeline of events effecting mosquito viral transmission. a Schematic of a typical livestock viraemia profile based on experimental infection of ruminants reviewed by Golnar et al. [28]. Viraemia is affected by both age and species of the host, dose, strain and route of inoculum [1], the schematic is therefore representative not absolute. Dotted lines represent a high threshold set by Golnar et al. [28] and a low dose threshold required to infect mosquitoes based on the findings of Vloet et al. [44], the latter facilitates onward infection of the mosquito across a longer duration than the high infectious dose [1]. b Interplay of the extrinsic incubation period (EIP) and mosquito lifespan on transmission. The EIP is the time from virus ingestion to the first point the mosquito is capable of expectorating virus via its saliva during feeding. The shorter the EIP and longer the lifespan the higher the potential for transmission events to occur, both are affected by multiple factors including environment and species specific traits. Scenario 1: short EIP but long lifespan is optimal for a transmission event; Scenario 2: long EIP with a long lifespan; Scenario 3: short EIP with a short lifespan; Scenario 4: long EIP coupled with short a lifespan does not support transmission. Arrows represent a feeding event, with the arrowhead indicating the direction of virus transmission. Red arrows and red sheep: events support transmission; black arrows and black sheep: events do not support transmission