Monkeypox is caused by a virus that is related to variola, the causative agent of smallpox. According to the authors of the review, Daniel B. Di Giulio and Paul B. Eckburg (Stanford University Medical School, Stanford, CA, USA), from the time of the first reported case of human monkeypox in 1970 until 2003, sporadic cases and outbreaks had been reported only from the rainforest areas of central and west Africa.
The disease, which may be clinically indistinguishable from chickenpox and smallpox, almost certainly arrived in the USA with rodents imported from west Africa for the pet trade. From the imported rodents, monkeypox spread to captive prairie dogs, and hence to human beings.
During the US outbreak, there were 81 reported human cases in six states, of which 32 were laboratory confirmed. There is no known treatment for monkeypox, although the disease was mild in the US cases with no fatalities. The possibility that monkeypox could become endemic in rodent populations in the USA must be guarded against, although there is no evidence that this has happened following the recent outbreak. Di Giulio and Eckburg conclude that "monkeypox is the most important orthopoxvirus infection in human beings since the eradication of smallpox in the 1970s".
Contact: Dr. Paul B. Eckburg, Division of Infectious Diseases, Stanford University Medical Center, 300 Pasteur Drive, Room S-156, Stanford, CA 94305, USA; T) 650-723-6661; E) eckburg1@stanford.edu .
The Lancet Infectious Diseases