COS 192-3 - Evaluating the efficacy of wMel dengue interventions under climate warming scenarios

Background/Question/Methods

Rising average temperatures and increasing temperature variability are impacting the geographic range and prevalence of mosquito-borne disease. A promising vector control technology replaces wild mosquitoes with those that carry a virus-blocking bacteria called Wolbachia. Recent laboratory and field observations show that the most widely used strain, wMel, is adversely affected by heat stress. Here, we extrapolate this information to understand the effect of climate change on public health interventions that employ wMel-based population replacement. We integrate empirical data on the temperature sensitivity of wMel bacteria into a mechanistic model of population dynamics for the dengue vector Aedes aegypti and use CMIP5 climate projections as well as historical temperature records specific to Cairns, Australia to simulate the dynamics of vector control in that region.

Results/Conclusions

While higher average temperatures tend to lower the frequency of wMel during the simulated introgression period, initial model results reflect field trials that demonstrate wMel fixation (high and stable equilibrium within the Ae. aegypti population) is robust to this facet of climate change. However, temperature variability in the form of more frequent and extreme heatwaves has the potential to reverse the public health benefits of this technology due to differences in thermal biology between wMel and their mosquito hosts. Preliminary outcomes from our simulations, calibrated to reflect laboratory data, demonstrate that heatwaves which cause daily average temperatures to meet or exceed 35°C can severely lower symbiont presence and in some model scenarios remove it entirely, restoring the vectorial capacity of Ae. aegypti former hosts. These results highlight the inextricable link between climate mitigation policy and infectious disease management: failure to curb carbon dioxide emissions will not only increase the proportion of the world exposed to deadly mosquito-borne illnesses due to rising temperatures; it will also undercut the utility of an otherwise demonstrably effective tool for vector control.