Reuters (UK), Dec. 7, 2007 A new virus called the chikungunya virus, which causes painful and sometimes crippling symptoms, has spread to several new countries in the past year because it has found a new species of mosquito to carry it, researchers said on Friday. A single mutation allowed the virus to infect the Asian tiger mosquito - which itself is spreading to many more countries in Europe and North America, the researchers said. "This mutation increases the potential for chikungunya virus to permanently extend its range into Europe and the Americas," Stephen Higgs and colleagues at UTMB wrote in their report, published in the Public Library of Science journal PLoS Pathogens. (This and similar reports have been appearing in global media.)