Aedes mosquitoes in the emerging threat of urban yellow fever transmission

This last decade has seen a resurgence of yellow fever (YF) in historical endemic regions and repeated attempts of YF introduction in YF-free countries such as the Asia-Pacific region and the Caribbean. Infected travellers are the main entry routes in these regions where competent mosquito vectors proliferate in appropriate environmental conditions. With the discovery of the 17D vaccine, it was thought that YF would be eradicated. Unfortunately, it was not the case and, contrary to dengue, chikungunya and Zika, factors that cotribute to YF transmission remain under investigation. Today, all the signals are red and it is very likely that YF will be the next pandemic in the YF-free regions where millions of people are immunologically naive. Unlike COVID-19, YF is associated with a high case-fatality rate and a high number of deaths are expected. This review gives an overview of global YF situation, including the non-endemic Asia-Pacific region and the Caribbean where Aedes aegypti is abundantly distributed, and also proposes different hypotheses on why YF outbreaks have not yet occurred despite high records of travellers importing YF into these regions and what role Aedes mosquitoes play in the emergence of urban YF.

Automated summary

In the past decade, there has been a resurgence of yellow fever in previously affected areas and attempts to introduce the disease in yellow fever-free regions such as the Asia-Pacific and the Caribbean. Infected travelers serve as the main source of entry in these regions, where suitable environmental conditions allow for the proliferation of competent mosquito vectors. Despite the discovery of the 17D vaccine, yellow fever has not been eradicated and the factors contributing to its transmission remain under investigation. Current indicators suggest that yellow fever may become the next pandemic in regions with a large immunologically naive population. Unlike COVID-19, yellow fever is associated with a high case-fatality rate and a significant number of deaths are expected.