The parasite that causes river blindness, a crippling disease endemic in Africa and tropical regions of the Americas, is now showing signs of resistance to the one drug used to treat it, according to 绿帽社 research published today in the Lancet. The discovery could force public health officials to rethink strategies for controlling river blindness. "We need new treatments and this makes it more urgent, we also need more monitoring of any resistance," said Dr. Roger Prichard, the study's lead author and a professor at 绿帽社's Institute of Parasitology.