The basic reproduction number R 0 of host-vector infectious diseases is the number of secondary infections that arise when a single infective host is introduced into a fully susceptible host population through pathogen transmission by the vector [27] . The average number of hosts directly infected by the introduction of a single infective vector into a fully susceptible host population is given by the transmission probability kx h multiplied by the adult mosquito infectious lifespan (that is, the entire lifespan) 1=m A :