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Monkeypox in Brief

Monkeypox is a virus closely related to smallpox and cowpox that historically has been found in Western and Central Africa. Cases have recently been identified in multiple countries across several continents. Case reporting can be followed using online compilations [1,2].

Here are answers to a few key questions:

  1. Where did the cases come from?
    The origins of this outbreak may be in a single confirmed case in a British resident who traveled to Nigeria where small Monkeypox outbreaks are occurring. He began to have Monkeypox symptoms and returned on May 4, 2022. By May 20, tens of confirmed or suspected cases were identified in Europe in the UK, Spain, Portugal, and a few cases in Germany, France, Belgium, Canada, US, Israel, and Australia. Many cases are in travelers, but community transmission appears to be occurring in the UK and other countries. A case in Massachusetts, US involved a traveler to Canada. The rapidity of the spread is surprising in view of both what is known about previous outbreaks spreading in Africa and in other locations. For example, during an outbreak in the US in 2003, all individuals who were infected were traced to contact with prairie dogs infected by imported animals from Africa [3]. In 2018, a UK outbreak starting from a traveler from Nigeria infected only two other individuals [4].While this presents a coherent picture, there is new evidence that Monkeypox may have been in Europe prior to May 4 [5].
  2. Why is it spreading so fast?
    There are multiple reasons why the Monkeypox outbreak might be spreading rapidly, including (1) A superspreader event associated with global travelers, (2) Changes in the properties of the virus due to mutating – recent sequencing suggests it has not changed significantly from the 2018 UK outbreak [6]. (3) Those who have been infected have reduced immunity due to prior Covid infection known to cause either (a) reduced barrier control through residual harm to the lungs [7], or (b) harm to immune system cells, i.e. T-cells [8].Recent reports suggest that large global social events in multiple countries have accelerated the transmission of Monkeypox, especially the Canaria Pride event involving 80,000 participants in the Canary Islands[9], and the Darklands Festival in Belgium[10]. More rapid transmission among gay men at these events does not preclude transmission to others, as may be manifest in reports of an infected child[11].
  3. Origin
    Monkeypox is a virus often found in forest mammals including rodents and monkeys. Transmission to humans (zoonotic transmission), has been linked to contact with bush meat, as well as with handling animals in and from Africa.
  4. Types
    There are two genetically distinct types of the Monkeypox virus, (1) the Central African clade (Congo region) with a mortality of 10% and significantly higher mortality in children, and (2) the West African clade, which is less lethal, with mortality of ~3%. The current global outbreak is caused by the Western African, less lethal, clade. Despite the lower mortality of this clade, symptoms are severe in 20-30% of cases, with disfiguring lesions, high fever, and sometimes respiratory symptoms.
  5. Transmission
    Monkeypox spreads in multiple ways: physical contact, bodily fluids, surfaces, droplets, and aerosols. Contact with skin lesions is particularly contagious. The virus has a high stability compared to many other viruses, and so persists in the air (longer than three days), and on surfaces (decontamination is with alcohol or diluted bleach).
  6. Detection
    Detection of Monkeypox based upon symptoms typically occurs when the rash begins based on the observation of blisters. PCR testing can be used for diagnosis.
  7. What happens when you get Monkeypox?
    The asymptomatic incubation period lasts about 7-14 days. Initial symptoms are typical of many viral infections, including a fever, headache, body aches, chills, and swollen lymph nodes. A rash of blisters develops a few days later beginning on the face and trunk and spreading from there, eventually including the upper body, palms and soles of feet. Initially, lesions are flat, then become elevated and fluid-filled. Active virus is and continues to be present in the lesions until they scab. The point at which transmission becomes possible is not well established, however, it begins around the time when initial symptoms arise and extends until all the scabs fall off. The symptomatic period lasts 2-4 weeks and the infectious period is approximately this long.
  8. Outcome
    In many cases Monkeypox resolves by itself after 2-4 weeks from symptom onset. Severe cases occur in 20-30% of cases of the less lethal variety (with high sustained fever, severe rash, encephalitis, respiratory symptoms, seizures), which leads to death in about 3% of cases. The lesions can leave scars [12].
  9. Immunity and susceptibility
    The smallpox vaccine is roughly 85% effective against Monkeypox. After eradication of smallpox, general vaccination was suspended in the 1970s. The fraction of the population that is susceptible has been increasing since. A large-scale roll-out of new or existing vaccines is not immediately possible due to a need to produce historical vaccines or to develop new ones. In areas where travel is limited, vaccination of contacts and other individuals likely to be infected in an area (ring vaccination) can be effective at prevention of spread.
  10. Prevention
    Due to the multiple possible routes of Monkeypox infection, effective prevention and limiting transmission requires multiple layers of preventive actions. These include:
    • Avoiding physical contact.
    • Not sharing food and drinks.
    • Avoiding sharing air and space with suspected/exposed people.
    • Avoiding crowded spaces, especially indoors.
    • Wearing high-quality masks, such as well-fitting N95 and KN95 masks.
    • Disinfection of surfaces, objects, and hands with ethanol wipes, ethanol solution (70%), or diluted bleach (1 tbsp per gallon or 4 liters of water).
    • Ventilation and air filtering (using HEPA purifiers).
    • If taking care of an ill person, wearing full PPE, including mask, goggles, gloves, and gowns.
    • Avoiding travel unless necessary. Avoid eating, drinking, or using restrooms during travel.
  11. Disinfection
    Unlike SARS-CoV-2, cleaning with soap and water and temperature treatment at 70°C=175°F do not reliably remove Monkeypox virus from surfaces. However, the use of 70% ethanol, as well as bleach solutions of 1 tbsp per gallon (4 liter) of water are considered to work well. The Monkeypox virus can remain active for several days, therefore, thorough sanitation is important to limit transmission.


  1. Monkeypox tab at
  2. BNO News at
  3. MG Reynolds et al, Spectrum of Infection and Risk Factors for Human Monkeypox, United States, 2003, Emerging Infectious Diseases, 13, 9, Sept. 2007.
  4. Monkeypox, Wikipedia, (accessed May 20, 2022)
  6. P. Selhorst et al, Belgian case of Monkeypox virus linked to outbreak in Portugal,
  7. R. Heiss et al, Persisting pulmonary dysfunction in pediatric post-acute Covid-19
  8. X-R Shen et al, ACE2-independent infection of T lymphocytes by SARS-CoV-2, Signal Transduction and Targeted Therapy, 7, 83 (2022)
  9. Monkeypox outbreak explodes across Europe as cases in Spain and Italy traced to island festival with 80,000 revellers
  12. See, e.g. Y.J. Hutin, Outbreak of human monkeypox, Democratic Republic of Congo, 1996 to 1997 Emerg Infect Dis. May-Jun; 7(3): 434–438 (2001)
Last reviewed on February 4, 2023

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