The first community-acquired outbreak of human monkeypox infection in the western hemisphere began in June 2003 in the US midwest and is being attributed to contact with infected exotic pets. Authorities from a variety of governmental agencies are investigated this outbreak, and a number of human cases had laboratory confirmation of monkeypox virus infection.
Concern over this outbreak will likely result in a call for tougher regulation of the exotic pet industry, especially related to imports of species from foreign countries. Restrictions are already being applied as a result of this outbreak (more on this later). Comparisons are being drawn between monkeypox and West Nile virus. West Nile virus had not been seen in North America prior to 1999, but has now become established across much of North America. Little research has been done on the monkeypox virus, and the potential for monkeypox to become established in North America is unknown. However, public unease over new or recently imported diseases (e.g. West Nile, SARS) is likely to have an impact on the exotic pet trade.
The Outbreak
As of the final report from the CDC on July 30, 2003, there were 72 suspected cases of monkeypox investigated, primarily in Wisconsin, Indiana, and Illinois. In 37 of those cases, monkeypox infection was confirmed by laboratory testing. Most of the affected people reported close contact with ill prairie dogs, although at least one case is thought to be related to an ill rabbit (who had contact with a sick prairie dog). There is no evidence that person-to-person transmission occurred in this outbreak.
It is suspected that Gambian giant rats imported from Africa were the source of the virus in this case, although this is not certain since monkeypox infection hasn't been confirmed in the involved rat(s). It is thought that the affected rat(s) were housed in the same facility as the affected prairie dogs, possibly in Illinois. It appears that the affected prairie dogs came from a single distributor in Illinois, who may have shipped prairie dogs to 15 states around the time of the outbreak. Authorities had some difficulty tracing the movement of any animals that may have been involved in this case, largely due to the fact that some of the affected animals apparently were obtained at an animal "swap meet."
Import of Gambian Rats and other African Rodents Stopped
As a result of this outbreak and the suspicion that Gambian rats were the source of the viral infection, the US Department of Health and Human Services (HSS) issued a embargo order on the import of rodents from Africa, effective June 11, 2003. In addition, HSS has also prohibited the distribution, sale, transport, or intentional release into the wild of prairie dogs and six African rodent species.
More information on the embargo order.
On November 4 2003, the restrictions were expanded and made permanent, with provisions to add other animals that are found to carry monkeypox to the ban in the future.
Permanent Restrictions on the Exotic Pet Trade in Prairie Dogs and African Rodents in the US