U.S. health officials have confirmed four cases of monkeypox, a virus similar to smallpox but less deadly and harder to transmit. It is the first known outbreak of the disease in the western hemisphere.
The Centers for Disease Control, or CDC, said Monday more than 30 other people in three midwestern states - Wisconsin, Indiana and Illinois - are suspected of contracting the disease. Investigators said all those infected had contact with sick prairie dogs, believed to be the carrier.
The prairie dogs could have contracted the disease from Gambian rats, both of which are sold as pets in the United States.
Symptoms of monkeypox are similar to smallpox, but less severe. CDC officials said they do not believe the illness can be spread from one human to another.