Prior to 2006, chikungunya was rarely seen in US travelers from endemic regions; however, from 2006 until 2013, an average of 28 cases per year were reported in US travelers. Chikungunya cases arrived in the northern Americas in 2013 from Africa to St. Martin in the Caribbean. The virus spread rapidly throughout Mexico, Central America, and South America. An Asian strain was also introduced to these areas.
The first case of chikungunya locally acquired in the US was reported in July 2014. This was only nine months after the first cases were reported in the Caribbean. By January 2016, 679 cases have been reported from 44 states. Almost all of these cases are from people traveling or emigrating from parts of the world where it is endemic. In 2014 there were 12 locally mosquito-transmitted cases in Florida.
According to the CDC, in 2016, a total of 248 chikungunya virus disease cases with illness onset in 2016 have been reported from 38 U.S. states (see map). All reported cases occurred in travelers returning from affected areas. No locally-transmitted cases have been reported from U.S. states. Also, a total of 181 chikungunya virus disease cases with illness onset in 2016 have been reported from U.S. territories. Of these, 180 were locally acquired cases reported from Puerto Rico and the US Virgin Islands. The remaining case occurred in a traveler returning from other affected areas.
The CDC reported that there were a total of 156 chikungunya virus disease cases with illness onset in 2017 from 28 U.S. states (see map). All reported cases occurred in travelers returning from affected areas. No locally-transmitted cases have been reported from U.S. states. Also, a total of 39 chikungunya virus disease cases with illness onset in 2017 have been reported from U.S. territories. To date, 39 locally acquired cases have been reported from Puerto Rico.
