Electron microscopy and testing by polymerase chain reaction and immunohistochemistry were used to confirm the causative agent was human monkeypox.

[3] On April 9, 2003, a Texas importer received a shipment of 762 African rodents from Accra, Ghana, which included rope squirrels (Funiscuirus sp.

CDC laboratory testing of animals from this shipment confirmed monkeypox by PCR and virus isolation in one Gambian rat, three dormice, and two rope squirrels.

This distributor shipped prairie dogs to pet stores in Wisconsin, Illinois, Indiana, Missouri, Kansas, South Carolina, and Michigan.

The Gambian rats and dormice housed with the prairie dogs at Illinois distributor number one tested positive for monkeypox virus.

[3] The most recent incidence of monkeypox prior to the Midwest outbreak occurred in the Democratic Republic of the Congo in 1996–1997, with a reported 88 cases.

People typically experienced fever, headaches, muscle aches, chills, and nonproductive coughs, followed 1–10 days later by a generalized papular rash which developed first on the trunk, then limbs and head.

[3] To prevent monkeypox virus from entering into the United States again, the Centers for Disease Control banned the importation of implicated African rodents.

[3] The U.S. Food and Drug Administration issued orders banning the interstate shipment of prairie dogs and all African rodents.