United Press International (Internet) 03/28/06 http://www.upi.com/NewsTrack/view.php?StoryID=20060327-081304-1355r Environmental change and viral mutations are fueling outbreaks of a mosquito-borne disease that has plagued South and Central America for 100 years. Researchers from the University of Texas Medical Branch at Galveston and Colorado State University discovered a single common genetic mutation can turn a harmless virus circulating among rodents in New World tropical forests into a strain of deadly Venezuelan equine encephalitis, or VEE, affecting humans, horses, donkeys and mules. The mutated virus multiplies very rapidly in equine species, spreading quickly via mosquitoes to other equines and humans. "The critical thing is really the presence of vulnerable equine species on these ranches in areas that used to be forests," said UTMB Pathology Professor Scott Weaver, senior author of the study.