CDC: Chikungunya officially in the US as of July 22.

CDC: Chikungunya officially in the US as of July 22. HT: Croft.

Via the CDC: United States Geographic Distribution | Chikungunya virus. Click through for the full report and a map. The key points, with my bolding:

• Chikungunya is not a nationally notifiable disease in the United States. However, chikungunya cases can be reported to ArboNET, the national surveillance system for arthropod-borne diseases. 

• From 2006‒2013, studies identified an average of 28 people per year in the United States with positive tests for recent chikungunya virus infection (Range 5‒65 per year). All were travelers visiting or returning to the United States from affected areas, mostly in Asia. Only a quarter of the cases were reported to ArboNET. 

• Beginning in 2014, cases have been identified in travelers returning from the Caribbean. As of July 22, a total of 497 chikungunya cases have been reported to ArboNET from U.S. states and territories (Table). One hundred ninety-seven locally-transmitted cases have been reported from Florida, Puerto Rico, and the US Virgin Islands. All other cases occurred in travelers returning from affected areas in the Caribbean and South America (N=295), the Pacific Islands (N=4), or Asia (N=1). 

• With the recent outbreaks in the Caribbean and the Pacific, the number of chikungunya cases among travelers visiting or returning to the United States from affected areas will likely increase. These imported cases could result in additional local spread of the virus in the continental United States.

Chikungunya in the Caribbean   

Most of the areas previously involved continue to report increasing case numbers. The situation is particularly severe on the island of Hispaniola (Haiti and the Dominican Republic) and in Guadeloupe. Both Costa Rica and Venezuela have reported confirmed cases, but it is not clear if they are imported or autochthonous. The United States reported the first locally acquired cases of chikungunya in Florida, one in Miami-Dade County, the other in Palm Beach County. According to media reports, Puerto Rico health officials declared a chikungunya epidemic, due to a rapidly rising number of cases there.   

An outbreak of chikungunya virus infection has been ongoing in the Caribbean since December 2013. There have been more than 350 000 probable and confirmed cases in the region with at least 21 fatalities reported. Many countries are reporting imported cases from the affected areas.   

ECDC published a risk assessment on 25 June and an epidemiological update on 30 June.