Fig. 5.
Arbovirus vector-mediated transmission cycle. (1) Extrinsic incubation period (EIP); the time during which an infected insect becomes infectious. (2) Vector-to-host transmission of virus through the bite of an infected Culicoides. (3) Intrinsic incubation period (IIP), the time during which the host becomes infectious. (4) Host-to-vector transmission of virus; when uninfected female Culicoides bite infected infectious hosts and become infected