ABSTRACT
The transmission of Zika virus (ZIKV) is a dynamic process defined by multiple factors. Specifically, the interaction of factors like vector competence and extrinsic incubation period (EIP) and age-dependent life traits has not been well quantified. We investigated the impact of mosquito age at time of exposure on the vector competence/EIP of Aedes aegypti for ZIKV, and found no significant differences between mosquitoes exposed at 5- or 12-days post-emergence. However, when these results were coupled with age-dependent life traits determined experimentally - lifespan and biting rate – we illustrate the necessity of putting vector competence and EIP into an age-structured construct. We demonstrate this by modifying the vectorial capacity (VC) equation, which describes the number of secondary cases of vector infection given the introduction of an infectious individual into a naïve population. By deriving an age-structured measure (VCage), we are able to quantitatively demonstrate the dynamism of the interaction of viral:vector transmission factors. These impacts of age are intuitive; however, our model puts such intuition into a quantitative framework. As technologies to age mosquitoes (or other vectors) in the field are pursued, VCage can inform hypotheses regarding the factors identifying the proportion of vectors that transmit relative to the total population.
Footnotes
We have rearranged the results and reworked the introduction and discussion to better get our point across. No direct changes to data or results.