Chikungunya on the Move in the U.S.

Locally acquired chikungunya virus (CHIKV) infection in the Caribbean was first documented in St. Martin in December 2013. The following month, passive chikungunya surveillance (built on the existing system to detect dengue) was initiated in Puerto Rico. The first locally acquired case to be detected in the territory occurred in May 2014; by August 2014, there were 10,201 suspected cases. CHIKV infection was confirmed in 68% of a 2910-specimen sample from these cases. In investigations around the households of individuals with confirmed CHIKV infection, 28% of the 250 participants tested positive for recent or current CHIKV infection, indicating lack of recognition and underreporting of this disease.

CHIKV and dengue virus are transmitted by Aedes aegypti and Aedes albopictus mosquitoes, both of which are prevalent in the Caribbean and the southeastern U.S. Both infections are characterized by fever and aches and pains. Arthralgias may be more common in chikungunya; dengue may be accompanied by leukopenia and minor bleeding. Subsequent infection with another of the four dengue virus strains leads to increased severity, whereas infection with the single CHIKV strain provides lifelong immunity. Death from chikungunya is rare, but risk is increased in people with underlying medical problems.

In Florida, 11 locally acquired cases have been reported — the first of them in June 2014. In addition, the state has reported 272 imported cases, with Haiti the most common country of exposure.