A cousin to the deadly smallpox virus, the monkeypox virus initially infects people through contact with wild animals and can then spread from person to person. The disease produces fever and a rash that often turns into painful lesions that can feel like cigarette burns. It kills up to 1 in 10 of its victims, similar to pneumonic plague, and is particularly dangerous in children. Monkeypox is on the U.S. government list of pathogens such as anthrax and Ebola with the greatest potential to threaten human health. There is no cure.