A second form of the painful chikungunya virus has appeared in Brazil—one that could more easily spread, including to the U.S.
When a mosquito-borne disease first arrived in the Western Hemisphere last year, humans were relatively lucky. The disease, which causes crippling joint pain persisting for weeks or even months and for which there is no known therapy or vaccine, hopscotched from the Caribbean islands to eventually land in the U.S. and the rest of the Americas. But the type of chikungunya creeping across the region then was one that could only readily spread via Aedes aegypti, a mosquito that is uncommon in the U.S.
New Type of More Problematic Mosquito-Borne Illness Detected in Brazil