Chikungunya is the latest virus you probably have never heard of. Carried by a couple of species of mosquito (both of which are found in the United States) and first described in Africa in 1952, the virus causes an abrupt onset of fever and severe joint pain (arthralgia) that may become chronic. Since that time, chikungunya has been found to be widespread in both Africa and Asia, and has now spread to the Caribbean islands and a few states in the U.S.
