The Centers for Disease Control and Prevention confirmed Friday that a Texas resident returning to the U.S. from Nigeria was infected with monkeypox, a relative of smallpox that causes a milder infection. The patient was hospitalized in Dallas after flying from Lagos to Atlanta on July 8 and from there to Dallas on July 9. Because passengers on both flights were required to wear masks, the CDC determined their risk of infection was small. The CDC describes monkeypox as “a rare but potentially serious viral illness that typically begins with flu-like illness and swelling of the lymph nodes and progresses to a widespread rash on the face and body.” It is fatal in 1 in 100 people.