According to the CDC, monkeypox is a rare but potentially serious viral illness that typically begins with flu-like illness and swelling of the lymph nodes. It also produces a widespread rash on the face and body and the infections generally last 2-4 weeks.
CDC experts say the infection is similar to smallpox but milder. They said lab testing showed the strain the U.S. traveler is infected with is a strain most commonly seen in West Africa, including Nigeria. The strain is fatal in roughly 1 in 100 people, but the risk of death increases for people with weakened immune systems.