514 www.thelancet.com Vol 383 February 8, 2014 circulated in New Caledonia, which harbours diff erent aminoacid deletion in the NSP3 gene. This episode represents the first evidence for the emergence of autochthonous chikungunya cases in the Americas. It is likely that the chikungunya epidemic will extend to other Caribbean islands, and it also has substantial potential for spreading from this region visited yearly by millions of tourists to the American mainland where A aegypti is endemic. Assuming that this strain will be transmitted effi ciently by A albopictus mosquitoes, its persistence in the Caribbean would also represent, as a consequence of seasonal synchronicity, a great threat for southern European countries where the mosquito has recently dispersed. This situation warrants reinforced epidemiological surveillance and specifi c preparedness.