Tracking West Nile virus dynamics using viral loads from trapped mosquitoes.

Pooled West Nile virus Ct values from retrospective U.S. mosquito surveillance show substantial variation that is not explained by laboratory factors alone, indicating biologically meaningful heterogeneity.

• Why it matters: Binarised RT-qPCR results can discard semi-quantitative viral-load information needed to better infer mosquito infectiousness and human exposure risk.
• What they did: The study developed a multi-scale model linking pooled Ct values to heterogeneous within-host viral kinetics in mosquitoes and birds plus seasonal transmission dynamics, then created a pooled-Ct method to estimate infection prevalence separating infectious from non-infectious mosquitoes.
• The result: Ct values from positive pools likely reflect mixtures of potentially infectious and non-infectious mosquitoes, and the infectious/non-infectious prevalence estimates were comparable to standard binarised methods while remaining accurate at higher prevalences where standard approaches fail.