Chikungunya Virus Disease among Travelers-United States, 2014-2016

Chikungunya virus is a mosquito-borne alphavirus that causes an acute febrile illness with severe polyarthralgia. The first local transmission of chikungunya virus in the Western Hemisphere was reported in December 2013. In the following year, the virus spread throughout much of the Americas and the number of cases among travelers increased substantially. We reviewed the epidemiology of chikungunya virus disease cases reported among U.S. travelers from 2014 to 2016. A total of 3,941 travel-acquired cases were reported from 49 states and the District of Columbia; 3,616 (92%) reported travel to other countries or territories in the Americas; the remaining 8% reported travel to Asia, Africa, or the Western Pacific. The most commonly reported travel destinations were the Dominican Republic, Puerto Rico, and Haiti. The largest number of cases (N = 2,780, 71%) had illness onset in 2014, followed by 2015 (N = 913, 23%) and 2016 (N = 248, 6%). Cases occurred in every month, but 70% of case-patients had illness onset from April to September, the months when mosquitoes are most likely to be active in the continental United States. Travel-acquired chikungunya cases will likely continue to occur and present a risk of introduction of the virus to locations in the continental United States. Clinicians and public health officials should be educated about the recognition, diagnosis, management, and timely reporting of chikungunya cases.