U.S. health officials are reporting the first known outbreak of human infections in the Western Hemispere of an African virus that resembles monkeypox.
The U.S. Centers for Disease Control says 19 people have been infected in the midwestern United States, with most of the cases in the state of Wisconsin.
Monkeypox occurs primarily in the rain forest countries of Central and West Africa. The illness is similar to, but less infectious than, smallpox. It is not usually fatal in humans.
Health officials said they believe the cases in the Midwest resulted from infected prairie dogs who came into a contact with a Gambian rat that may have had the virus. The animals were sold as pets.