Puerto Rico became the latest country to declare an official epidemic of the mosquito-borne virus chikungunya, as health officials in the United States identified the first domestic cases of the virus.
On Thursday, Puerto Rican Health Secretary Ana Rius said that more than 200 cases had been confirmed as of June 25, a sharp increase since the first case on the island was reported in May.
The virus has been spreading across the Caribbean since December 2013, when the first locally transmitted case in the Western Hemisphere was identified in the French Caribbean territory of St. Martin. In those seven months, the virus has spread to 23 different countries and territories across the Caribbean.
In the Dominican Republic alone, the chikungunya epidemic has reached 19 provinces since it arrived in April, infecting more 193,000 people and killing three. Neighboring Haiti, which is already facing a serious cholera epidemic, has seen an explosion in the number of chikungunya cases. The Pan American Health Organization estimates that more than 50,000 Haitians may be infected, bringing the total for the two nations, which share one island, to more than 240,000 cases.
The organization has recorded more than 354,000 suspected and confirmed cases and 21 deaths as of July 11.
On Thursday, U.S. health officials announced the first confirmed cases, both in Florida, in two people who had not recently traveled to affected regions. According to the Centers for Disease Control and Prevention, 357 cases have been reported in 31 states and two territories so far in 2014.
“The newly reported case represents the first time that mosquitoes in the continental United States are thought to have spread the virus to a non-traveler,” the CDC said in an official statement. “This year, Puerto Rico and the U.S. Virgin Islands reported 121 and two cases of locally acquired chikungunya respectively.”
Chikungunya was first identified in Tanzania in 1952. It is not usually fatal, but causes a high fever, strong headache and swelling around joints. There is no vaccine, and it mainly is treated with pain medication.
Additional reporting by Associated Press