The European Centre for Disease Prevention and Control (ECDC) announced on Jan. 7 that confirmed and probable chikungunya (CHIKV) cases in the eastern Caribbean had increased by 41 percent in the last week. A total of 1,453 chikungunya cases have been reported, and four locales have stopped laboratory testing for the viral illness due to the large number of cases. Saint Martin, Martinique, Saint Barthélemy and Guadeloupe are no longer systematically testing every potential patient.
The outbreak of the mosquito carried illness remains centered on the French speaking islands east of Puerto Rico. Fully 95 percent of all reported chikungunya cases are from five islands and French Guyana on the South American mainland. Guyana has seen four cases but all were imported from St. Martin or Martinique. The disease has not yet made its way to the mainland as a locally acquired illness.
The Dutch side of the island of St. Martin saw the number of confirmed CHIKV cases jump during the last week from nine to 60. Another Dutch island, Aruba, saw its first case, believed to have been imported.
The British Virgin Islands reported a total of six chikungunya cases, an increase of three. Dominica saw no change for the week, with three locally acquired CHIKV cases and one imported case. Anguilla reported it first case, imported from St. Martin.
Locally acquired cases of chikungunya were first discovered in early Dec. 2013, on the French side of the island of St. Martin. The illness had never been locally acquired in the Western Hemisphere before then. The chikungunya virus is transmitted by two varieties of mosquito, the Yellow Fever mosquito and the Asian Tiger mosquito. Both vectors are common throughout the Caribbean, and in both North and South America. Both mosquitoes are the primary carriers of dengue fever, which is currently endemic in Puerto Rico and much of Central and South America.
The Centers for Disease Control began preparing for the expected arrival of chikungunya in this hemisphere several years ago. It is expected to eventually be found in all areas where the two mosquito vectors live. Outbreaks have occurred in both Italy and France, and the ECDC remains on alert. The agency noted in December that the Asian Tiger mosquito is well established in Europe, and especially in the areas around the Mediterranean.