Science Magazine (Internet / Print) 05/24/06 Scientists are beginning to unravel the causes behind a massive outbreak of a little-known viral disease that's plaguing islands in the Indian Ocean. A broad sequencing study has yielded hints that the culprit, called the Chikungunya virus, may recently have undergone mutations that have made it more adept at causing infections. But further work is needed to prove the links. "It's good work, and they've done lots of sequencing," says Scott Weaver, an expert in insect-borne viruses at the University of Texas Medical Branch in Galveston. But for now, any link between viral sequence and epidemiology remains "very speculative," he says.