For more than half a century, monkeypox was a rare infectious disease confined to one region of the world. At some point in the past few years, monkeypox jumped from an animal to a person and then kept spreading, infectious-disease experts believe.
Genetic mutations suggest current outbreak can be traced to animal-to-human infection from April 2016, according to one analysis
U.S. health officials have declared monkeypox a public-health emergency, after the World Health Organization declared it a global health emergency in late July. WSJ explains what you should look out for and what scientists know about how the virus is spreading. Illustration: Adele Morganconfined to one region of the world. A few months ago, that suddenly changed. Scientists are building a picture of what happened.
The explosion of monkeypox around the world is a case study in how infectious diseases can leap from limited circulation to wide geographic spread with just a few chance events. Infectious-disease experts knew that