We present a model that explicitly links the epidemiological Ross-Macdonald model with a simple immunological model through a virus inoculation term that depends on the abundance of infected mosquitoes. We explore the relationship between the reproductive numbers at the population (between-host) and individual level (within-host), in particular the role that viral load and viral clearance rate play in the coupled dynamics. Our model shows that under certain conditions on the strength of the coupling and the immunological response of the host, there can be sustained low viral load infections, with a within-host reproduction number below one that still can trigger epidemic outbreaks provided the between host reproduction number is greater than one. We also describe a particular kind of transmission-clearance trade off for vector-host systems with a simple structure.