The Food and Drug Administration in September removed its restrictions on several species of African rodents and on prairie dogs that can carry or spread monkeypox, a rare viral disease found mostly in central and western Africa that can be fatal in humans.

The agency said it removed its ban on the interstate movement of the animals because there have been no new cases of monkeypox in the United States since a 2003 outbreak that was ultimately traced to a shipment of 800 small mammals imported from Ghana to a Texas distributor.

Furthermore, a risk assessment published in 2006 suggests that the risk of further domestically acquired human monkeypox cases in the United States is low, the FDA said.

However, regulations that restrict the importation of all African rodents, administered and enforced by the Centers for Disease Control and Prevention, remain in effect to prevent any re-introduction of the monkeypox virus into the United States.

The monkeypox virus entered the United States in 2003 through diseased African rodents. When the African rodents were co-housed with prairie dogs at a Midwestern distributor’s facility, the prairie dogs acquired monkeypox and, in turn, transmitted the disease to humans across several states.

There were 72 possible human cases of monkeypox during the 2003 outbreak, 47 of which were confirmed by laboratory tests. Some patients were hospitalized and one patient required a corneal transplant. There were no deaths.

Monkeypox is transmitted through contact with the blood, bodily fluids or rash of an infected animal. Rodents can carry the monkeypox virus with no symptoms or signs of infection.

The FDA and CDC joint restrictions were issued first as an order in June 2003 and later as an interim final rule on Nov. 4, 2003.  [November 2008 PET AGE]