Yellow Fever Emergence: Role of Heterologous Flavivirus Immunity in Preventing Urban Transmission

Abstract

AbstractDuring major, recent yellow fever (YF) epidemics in Brazil, human cases were attributed only to spillover infections from sylvatic transmission with no evidence of human amplification. Furthermore, the historic absence of YF in Asia, despite abundant peridomesticAedes aegyptiand naive human populations, represents a longstanding enigma. We tested the hypothesis that immunity from dengue (DENV) and Zika (ZIKV) flaviviruses limits YF virus (YFV) viremia and transmission byAe. aegypti. Prior DENV and ZIKV immunity consistently suppressed YFV viremia in experimentally infected macaques, leading to reductions inAe. aegyptiinfection when mosquitoes were fed on infected animals. These results indicate that, in DENV- and ZIKV-endemic regions such as South America and Asia, flavivirus immunity suppresses YFV human amplification potential, reducing the risk of urban outbreaks.One-Sentence SummaryImmunity from dengue and Zika viruses suppresses yellow fever viremia, preventing infection of mosquitoes and reducing the risk of epidemics.