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Monkeypox VirusMonkeypox is a rare disease that is caused by infection with monkeypox virus. Monkeypox virus belongs to the Orthopoxvirus genus which also includes variola virus (which causes smallpox), vaccinia virus (used in the smallpox vaccine), and cowpox virus.

Transmission occurs when an individual comes into contact with the virus from an animal, human, or materials contaminated with the virus. The virus enters the body through broken skin (even if not visible) or the respiratory tract (eyes, nose, or mouth). Human-to-human transmission is thought to occur primarily through large respiratory droplets requiring prolonged face-to-face contact.

The natural reservoir of monkeypox remains unknown. However, African rodents and non-human primates (like monkeys) may harbor the virus and infect people.


In Africa, monkeypox has been shown to cause death in as many as 1 in 10 persons who contract the disease.

Monkeypox was first discovered in 1958 when two outbreaks of a pox-like disease occurred in colonies of monkeys kept for research. The first human case of monkeypox was recorded in 1970 in the Democratic Republic of the Congo during a period of intensified effort to eliminate smallpox. Since then, monkeypox has been reported in people in several other central and western African countries: Cameroon, Central African Republic, Cote d’Ivoire, Democratic Republic of the Congo, Gabon, Liberia, Nigeria, Republic of the Congo, and Sierra Leone. The majority of infections are in the Democratic Republic of the Congo.

US monkeypox cases are very rare. Monkeypox does not occur naturally in the US, but cases have occurred that were associated with international travel or importing animals from areas where the disease is more common.

The Centers for Disease Control and Prevention (CDC) is currently tracking monkeypox cases in countries that do not normally report monkeypox including in Europe and the US. Cases include people who self-identify as men who have sex with men. CDC is urging US healthcare professionals to be alert for patients who have rash illness consistent with monkeypox, regardless of travel history, risk factors, or gender or sexual orientation.


In humans, the symptoms of monkeypox are similar to, but milder than, the symptoms of smallpox. Monkeypox begins with fever, headache, muscle aches, swollen lymph nodes, chills, and exhaustion. The incubation period for monkeypox is usually 7−14 days. Within 1 to 3 days (sometimes longer) after the appearance of fever, the infected individual develops a rash, often beginning on the face and then spreading to other parts of the body. The illness typically lasts for 2−4 weeks.


Monkeypox infection can be prevented by:

  • Avoiding contact with animals that could harbor the virus (including animals that are sick or that have been found dead in areas where monkeypox occurs) and any materials (such as bedding) that have been in contact with a sick animal
  • Isolating infected patients from others who could be at risk for infection
  • Washing hands with soap and water or using an alcohol-based hand sanitizer after contact with infected animals or humans

JYNNEOSTM  is an attenuated live virus vaccine which has been approved by the US Food and Drug Administration for the prevention of monkeypox and is being evaluated by the Advisory Committee on Immunization Practices (ACIP) for the protection of those at risk of occupational exposure to orthopoxviruses, such as smallpox and monkeypox, in a pre-event setting.


Currently, there is no proven, safe treatment for monkeypox virus infection. To control a monkeypox outbreak in the US, smallpox vaccine, antivirals, and vaccinia immune globulin (VIG) may be used.

If you think you may have monkeypox, talk to a healthcare professional as soon as possible.


Reviewed May 2022

Source: Centers for Disease Control and Prevention