Most cases of dengue in the US are imported from people who traveled to or emigrated from endemic areas of the world. It is the most common cause of fever in travelers returning from tropical or subtropical areas of the Caribbean, Latin America, and Asia. The map shows cases imported to the US from endemic areas in 2015.
Dengue infections are seen in US citizens who live in Puerto Rico, the US Virgin Islands, Samoa, and Guam where the Aedes aegypti mosquito is found in large numbers year-round. There was a large epidemic (10,000 confirmed cases) in Puerto Rico in 2007. The high transmission season there is August to November and the low transmission season is March until July.
Three outbreaks of dengue transmitted by mosquitoes have been reported by the CDC in the US. One was in Hawaii in 2001 and the second was in Texas in 2005 on the Mexican border. The third was in Key West, Florida in 2009. Secondary transmission is rare.
