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Mosquito-borne viruses, such as dengue, chikungunya, and Zika, already threaten over a billion people globally. A study published on March 28, 2019, in PLOS Neglected Tropical Diseases predicts that climate change and rising global temperatures will lead to both increased and new exposures to humans of diseases carried by mosquito vectors Aedes aegypti and Ae. albopictus. The most extreme instances of transmission are predicted to occur at intermediate climate change scenarios.
Sadie Ryan of the University of Florida and her colleagues forecasted climate change impact on virus-carrying mosquitoes by adapting a previously developed Bayesian transmission model. The researchers’ adaptation of the model allowed them to track shifting weather warming scenarios to determine where mosquitoes will migrate and how the number of disease transmissions will change over the next century.
Ae. aegypti is estimated to have a higher thermal optimum for transmission than Ae. albopictus (29 degrees Celsius vs. 26 degrees C). The researchers’ results show that when the mosquito range shifts within optimal temperature ranges for transmission (21.3 — 34.0° C for Ae. aegypti; 19.9 — 29.4° C for Ae. albopictus), we can expect poleward shifts in Aedes-borne virus distributions. While disease transmission to humans is predicted to increase in Europe, transmission from Ae. albopictus may decrease in southeast Asia and west Africa when the researchers’ worst-case scenario is applied. Counter-intuitively, a middle-of-the-road temperature increase could produce the greatest expansion in viral transmission by Ae. albopictus, as opposed to hypotheses that predict a paralleled increase in temperature with illness — a model that predicts a warmer, sicker world.
“The dynamics of mosquito-borne illnesses are climate-driven, and current work suggests that climate change will dramatically increase the potential for expansion and intensification of Aedes-borne virus transmission within the next century,” the authors note.