2003 Midwest mpox outbreak
An outbreak of human monkeypox began in May 2003 in the United States. By July, a total of 71 cases were found in six Midwestern states including Wisconsin, Indiana, Illinois, Kansas, Missouri, and Ohio. The cause of the outbreak was traced to three species of African rodents imported from Ghana on April 9, 2003, into the United States by an exotic animal importer in Texas. These were shipped from Texas to an Illinois distributor, who housed them with prairie dogs, which then became infected.
The outbreak marked the first time monkeypox infection appeared in the Western Hemisphere. No deaths were reported, and no human-to-human transmission was found. All cases involved direct contact with infected prairie dogs. Electron microscopy and testing by polymerase chain reaction and immunohistochemistry were used to confirm the causative agent was human monkeypox.
Timeline
In May 2003, a three-year-old Wisconsin resident was bitten by a prairie dog purchased from a local pet store. The child was hospitalized after developing fever of unknown origin, swollen eyes, and a red vesicular skin rash. The child's parents also developed a rash, but no other symptoms. Physicians immediately associated the symptoms with the animal bite and reported the case to the Milwaukee Health Department. Testing of both the child and the prairie dog confirmed the monkeypox virus as the causative agent.Between May 15, 2003, when the three-year-old index patient was first diagnosed through June 20, the date of the last patient with a laboratory-confirmed case of monkeypox, a total of 71 people ranging in age from 1 to 51 were infected.
Transmission
No human-to-human transmission was found during this outbreak. All cases were found to be the direct result of contact with infected prairie dogs.Signs and symptoms
The onset of the illness among affected persons in the United States began in early May 2003. 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. The papules evolved through phases of vesiculation, pustulation, umbilication, and crusting. All persons reported direct or close contact with recently acquired prairie dogs.Treatment
As no direct antiviral treatment for monkeypox was known, only supportive care and prevention of secondary infection was recommended.Use of smallpox vaccine
In the Midwest outbreak, the CDC issued guidance on the use of smallpox vaccine, Cidofovir, and Vaccinia immune globulin. Thirty residents in six states received the smallpox vaccination. This included 28 adults and two children. Vaccine was given before exposure to seven persons and after exposure to 23 persons. Three reported rash within 2 weeks of vaccination.Further action
To prevent monkeypox virus from entering into the United States again, the Centers for Disease Control banned the importation of implicated African rodents.The U.S. Food and Drug Administration issued orders banning the interstate shipment of prairie dogs and all African rodents. The bans were later lifted in 2008.