Research shows dengue moving north

According to government research released this week, five percent of the population of Key West, Florida, has been infected at some point with the dengue virus.

The findings revealed that the deadly infection has begun making its way into the United States, researchers told Reuters.

"We're concerned that if dengue gains a foothold in Key West, it will travel to other southern cities where the mosquito that transmits dengue is present, like Miami," Harold Margolis, chief of the dengue branch at the U.S. Centers for Disease Control and Prevention, told Reuters. "These cases represent the reemergence of dengue fever in Florida and elsewhere in the United States after 75 years.

"These people had not traveled outside of Florida, so we need to determine if these cases are an isolated occurrence or if dengue has once again become endemic in the continental United States."

Annually, as many as 100 million people are infected with dengue, which is the most common virus transmitted by mosquitoes. There are 25,000 dengue-related deaths each year.

Dengue symptoms are generally flu-like, Reuters reports, but may also take on a hemorrhagic form that involves internal and external bleeding and sudden death.

The United States considered dengue eradicated in the 1940s, though a few scattered cases have been confirmed along the Texas-Mexico border since the 1980s. Florida reported 27 cases of dengue in 2009.