Monkeypox: a review of the history and emergence in the Western hemisphere

A mysterious disease was reported on May 24, 2003, when the Wisconsin Division of Public Health (DPH) received notice of a 3-year-old girl who had been hospitalized in central Wisconsin with cellulites and fever after being bitten by a prairie dog on May 13. The laboratory isolated a gram-negative bacillus, raising concerns that it might be tularemia or plague; ultimately, it was identified as an acinetobacter species and was considered to be a contaminant. Because no other such cases were reported at the time, the case was thought to be merely an isolated event. However, within two weeks, on June 2, 2003, evidence of a much wider scenario began to emerge. On that date, the Wisconsin DPH received notice from the Marshfield Laboratory that the mother of the first patient had become ill on May 26 and that electron-microscopic evidence of a poxvirus was found in a skin lesion. On that same day, another report, this time from the Milwaukee Health Department, of a strange illness was received at the DPH and described the case of a meat inspector who resided in southeastern Wisconsin and also was a distributor of exotic animals. By July 30, 2003, 72 confirmed or suspected cases of monkeypox had been reported in Wisconsin, Illinois, and Indiana and represented a large outbreak. The peak in the onset of illness occurred between May 29 and June 9, 2003, and no further cases of illness have been reported in humans since June 22, 2003. Traceback investigations from the child and other patients followed the route of introduction of monkeypox into Wisconsin to a distributor in Illinois, who had received a shipment of exotic animals imported into the United States through Texas from Ghana, West Africa.