Chikungunya: Evolutionary history and recent epidemic spread.

Chikungunya virus (CHIKV) has a long history of emergence into urban transmission cycles from its ancestral, enzootic, sylvatic foci in Sub-Saharan Africa, most recently spreading to the Americas beginning in 2013. Since 2004, reemergence has resulted in millions of cases of severe, debilitating and often chronic arthralgia on five continents. Here, we review this history based on phylogenetic studies, and discuss probable future spread and disease in the Americas. We also discuss a series of mutations in the recently emerged Indian Ocean Lineage that has adapted the virus for transmission for the first time by the Aedes albopictus urban mosquito vector, and compare CHIKV to other arboviruses with and without similar histories of urbanization. This article forms part of a symposium in Antiviral Research on "Chikungunya discovers the New World."