Monkeypox is a rare zoonotic (animal-borne) viral disease similar to smallpox. The virus responsible for monkeypox is, in fact, related to that responsible for smallpox. Both belong to the orthopox family of viruses.
Vaccination against smallpox gives protection against monkeypox. Before the eradication of smallpox, vaccination was widely practiced and protected against both diseases. However, most children born after 1980 have not been vaccinated against smallpox and are more susceptible to monkeypox than older members of the population. The death rate from monkeypox is highest in young children, reaching about 10%.
Infection with the monkeypox virus results in an exanthem (an illness with a rash on the skin) similar to but less contagious than smallpox. The incubation period is about 12 days. Symptoms may include fever, cough, headache, myalgia (muscle aches and pain), rash, or lymph node enlargement (swollen glands) within 3 weeks after contact with than infected animal.
Most human cases of monkeypox occur in remote villages in Central and West Africa close to tropical rainforests where there is frequent contact with infected animals. Monkeypox is usually transmitted to people through contact with the animal's blood or through a bite by the animal. Animal species susceptible to monkeypox virus include non-human primates (such as monkeys), rabbits, and some other rodents. In 2003, an outbreak of monkeypox occurred in the upper midwestern U.S. due to contact with exotic pets, namely, Gambian rats and prairie dogs.
In November 2022, the World Health Organization renamed "monkeypox" as "mpox."