Global spread of chikungunya virus: A lesson for Aedes-transmitted arboviruses?

Chikungunya virus (CHIKV) is an arbovirus, transmitted by Aedes aegypti and Ae. albopictus, which causes epidemics of fever, rash and joint pains. First described in 1952 in Tanzania, CHIKV remained a relatively neglected tropical virus, despite causing sporadic outbreaks in Africa and Asia over the next few decades. However, since 2004, an epidemic lineage of the East/Central/South African (ECSA) genotype has arisen in East Africa and spread to cause unprecedented global outbreaks in the Indian Ocean islands, South and Southeast Asia, as well as autochthonous outbreaks in Europe. This spread was driven by mutations in the virus envelope proteins that improved the vectorial competence of Ae. albopictus, which is widely distributed in the affected areas, and which was previously considered a vector of secondary importance to Ae. aegypti. In 2011, the Asian lineage of CHIKV emerged to cause outbreaks in Pacific islands, before unexpectedly spreading to cause explosive epidemics in the Caribbean and Latin America, mainly via Ae. aegypti. The factors behind the global spread of previously niche arboviruses such as CHIKV and more recently Zika virus are complex, multifactorial and poorly understood. The implications on strained health services and economies are considerable, particularly as CHIKV is associated with long-term rheumatological disorders. However, with the increasing ease of global travel and the growing geographical distributions of Aedes mosquito vectors, we should expect further spread of exotic arboviruses to new populations who remain entirely immunologically naive. © 2016 CAB International.