An excruciating mosquito-borne illness that arrived less than a year ago in the Americas is raging across the region, leaping from the Caribbean to the Central and South American mainland and infecting more than 1 million people. Some cases already have emerged in the United States. There have been a few locally transmitted cases in Florida, and it has the potential to spread farther, experts say, but Central and South America are particularly vulnerable with the prevalence of the main vector for the virus, the aedes aegypti mosquito, and the lack of immunity in a population that hasn't been hit with chikungunya in modern medical history, said Scott Weaver, director of the Institute for Human Infections and Immunity at UTMB. "There are going to be some very large populations at risk down there, much larger than the Caribbean," Weaver said. The Associated Press article appears in dozens of news outlets around the world, including KTRK-TV (Houston), the Denver Post, the Miami Herald and AOL.com.