When the body receives an injury to the skin, a signal is sent to the brain, which generates a sensation of pain. Researchers have studied lesions in patients with Buruli ulcer, a tropical disease. They show that, despite the extent and severity of these wounds, they are less painful than others that seem relatively minor (e.g. scratches, low-degree burns). They discovered an analgesic mechanism that limits the transmission of pain signals to the brain. An understanding of this mechanism may be useful in developing new drugs for pain relief.