Zika virus, a new threat for Europe?

Abstract Background: Since its emergence in 2007 in Micronesia and Polynesia, the arthropod-borne flavivirus Zika virus (ZIKV) has spread in the Americas and the Caribbean, following first detection in Brazil in May 2015. The risk of ZIKV emergence in Europe increases as imported cases are repeatedly reported. Together with chikungunya virus (CHIKV) and dengue virus (DENV), ZIKV is transmitted by Aedes mosquitoes. Any countries where these mosquitoes are present could be potential sites for future ZIKV outbreak. Methodology/Principal Findings: Mosquito females were challenged with an Asian genotype of ZIKV. Fully engorged mosquitoes were then maintained in insectary conditions (28°±1°C, 16h:8h light:dark cycle and 80% humidity). 16-24 mosquitoes from each population were examined at 3, 6, 9 and 14 days postinfection to estimate the infection, disseminated infection and transmission rates. Based on these experimental infections, we demonstrated that Ae. albopictus from France were not very susceptible to ZIKV. Conclusions/Significance: In combination with the restricted distribution and lower population densities of European Ae. albopictus , our results corroborate the low risk for ZIKV to expand into most parts of Europe with the possible exception of the warmest regions bordering the Mediterranean coastline. Author summary In May 2015, local transmission of Zika virus (ZIKV) was reported in Brazil and since then, more than 1.5 million human cases have been reported in Latin America and the Caribbean. This arbovirus, primarily found in Africa and Asia, is mainly transmitted by Aedes mosquitoes, Aedes aegypti and Aedes albopictus . Viremic travelers returning from America to European countries where Ae. albopictus is established can become the source for local transmission of ZIKV. In order to estimate the risk of seeding ZIKV into local mosquito populations, the ability of European Ae. aegypti and Ae. albopictus to transmit ZIKV was measured using experimental infections. We demonstrated that Ae. albopictus and Ae. aegypti from Europe were not very susceptible to ZIKV. The threat for a Zika outbreak in Europe should be limited.