This a rare disease that has never occurred before in North America. The current outbreak has resulted in 62 suspected cases in Wisconsin, Illinois, Indiana, and New Jersey; of these, 9 cases have been clinically confirmed.
Monkeypox is a virus from the same family as the smallpox virus, and naturally occurs in Central and West Africa.
The virus' name is derived from the fact that this disease was first found in laboratory monkeys in 1958. However, it appears that the natural hosts for this virus are African rodents, specifically the African squirrel. The first case in humans was reported in 1970. It is believed that transmission of the disease is caused by animal bite or direct contact with the animal’s lesions or body fluids.
The American cases are the result of close contact of infected prairie dogs that had been purchased as pets from a pet shop in Chicago, IL. Giant Gambian rats destined for the exotic pet trade in the US carried the disease from Africa to the United States. These rats then infected wild-caught prairie dogs from Texas also destined for the pet industry.
The current outbreak highlights the dangers of keeping exotic wildlife as pets. Even dogs and cats, who have evolved in the presence of humans into domesticated animals over thousands of years still have the ability to transmit diseases such as parasitic infections and rabies to humans. Exotic animals that humans have never had any prolonged exposure to, may harbor harmful pathogens that can be transmitted to humans.