Monkeypox virus


Monkeypox virus is a double-stranded DNA, zoonotic virus and a species of the genus Orthopoxvirus in the family Poxviridae. It is one of the human orthopoxviruses that includes variola, cowpox, and vaccinia viruses. But it is not a direct ancestor to, nor a direct descendant of, the variola virus which causes smallpox. Monkeypox virus causes a disease that is similar to smallpox, but with a milder rash and lower death rate. Variation in virulence of the virus has been observed in isolates from Central Africa where strains are more virulent than those from Western Africa.

Reservoir

Monkeypox is carried by both animals and humans. It was first identified by Preben von Magnus in Copenhagen, Denmark in 1958 in crab-eating macaque monkeys being used as laboratory animals. It has also been identified in the giant Gambian rat which was the source of a 2003 outbreak in the United States.
Monkeypox virus causes the disease in both humans and animals. The crab-eating macaque is often used for neurological experiments. The virus is mainly found in tropical rainforest regions of central and West Africa.

Transmission

The virus can spread both from animal to human and from human to human. Infection from animal to human can occur via an animal bite or by direct contact with an infected animal’s bodily fluids. The virus can spread from human to human by both droplet respiration and contact with fomites from an infected person's bodily fluids. Incubation period is 10–14 days. Prodromal symptoms include swelling of lymph nodes, muscle pain, headache, fever, prior to the emergence of the rash.

Epidemiology

The virus is mainly found in the tropical forests of Central Africa and West Africa. It was first discovered in monkeys in 1958, and in humans in 1970. Between 1970 and 1986, over 400 cases in humans were reported. Small viral outbreaks with a death rate in the range of 10% and a secondary human to human infection rate of about the same amount occur routinely in equatorial Central and West Africa. The primary route of infection is thought to be contact with the infected animals or their bodily fluids. The first reported outbreak in the United States occurred in 2003 in the midwestern states of Illinois, Indiana, and Wisconsin, with one occurrence in New Jersey. The outbreak was traced to prairie dogs infected from an imported Gambian pouch rat. No deaths occurred.