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    Monkeypox for the Emergency Clinician


    Last Updated Jun 15, 2022
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    • Monkeypox is an endemic disease in the Congo Basin and West Africa.
    • In May of 2022, there were reports of community transmission of monkeypox in London, England which eventually spread to North America.
    • 2 distinct types/clades: Congo Basin clade of the virus has a case fatality of 1 – 10%, the West Africa clade has a case fatality rate of 1%.
    • Names of these clades will likely be renamed by the World Health Organization (WHO) to avoid stigmatization.
    • Monkeypox is member of the poxviridae family which includes molluscum contagiousum, vaccinia and smallpox.
    • First case was identified in 1970 in a 9-year old boy in the Democratic Republic of Congo.
    • Despite the name and the fact it was initially identified in monkeys, the exact animal reservoir is unknown.
    • As of June 14, 2022 there have been 1600 confirmed cases, 1500 suspected cases and 72 deaths in 39 countries.
    Monkeypox lesion

    Monkeypox lesion. Photo: CDC


    • Limited data available.
    • Likely spread from infected animals to humans either directly or indirectly through bites, scratches, hunting, skinning.
    • Human to human transmission through direct contact with infectious skin or lesions, respiratory droplets and possibly short range aerosols.
    • Potential fomite transmission through contaminated clothing, linen.
    • High proportion of cases identified in patients who identify as gay, bisexual and men who have sex with men – potentially related to positive health behaviours and strong connections to STI resources.

    Clinical Presentation:

    • Non-specific viral illness, less dramatic and often fewer lesions than smallpox.
    • First phase (1 -5 days): fever, headache, myalgias, lymphadenopathy.
    • Second phase (1-3 days): fever subsides and rash appears which progresses in a stereotypical fashion – macule, papule, vesicle, pustule, umbilicate lesion, crusting and desquamation.
    • Rash typically starts on the face and extended to the palms, soles and feet, mucous membranes.
    • 75% of cases in North America and Europe present initially with genital lesions.
    • Risk factors for severe disease: viral DNA count, number of skin lesions, AST and ALT on day of diagnosis.

    Differential Diagnosis:

    • Viruses: HSV, VSV, molluscum contagiousum.
    • Bacteria: MRSA.
    • STIs: syphilis, lymphogranuloma venereum, granuloma inguinale.

    Recommended Treatment


    • Place patient in negative pressure room with airborne, droplet and contact precautions for all patient encounters.
    • Call infection prevention and control, medical microbiology and infectious disease consulting services.
    • Report case to regional public health office.
    • Exposed contacts (including healthcare workers without adequate PPE) should self-monitor for 21 days.
    • Lesions should be de-roofed and at least 2 lesions and an oropharyngeal swab should be taken using standard red collection tubes.
    • Mainstay of treatment is supportive care and analgesia.
    • Tecovirimat is an anti-viral licensed for the treatment of smallpox – may be used for more severe cases as per infectious diseases under special use authorization.
    • As per the World Health organization, potential post-exposure prophylaxis with IMVAMUNE, a live attenuated, non-replicating smallpox vaccine up to 2 weeks after an exposure to a potential or confirmed case.

    Treatment not recommended:

    • Prophylactic antibiotics unless overlying skin and soft tissue infection.

    Quality Of Evidence?


    Low – this is an ongoing outbreak with little clinical data to support the current recommendations.


    Related Information


    1. Nalca A, Rimoin AW, Bavari S, Whitehouse CA. Reemergence of monkeypox: prevalence, diagnostics, and countermeasures. Clin Infect Dis 2005; 41:1765.

    2. World Health Organization. Monkeypox fact sheet. https://www.who.int/news-room/fact-sheets/detail/monkeypox (Accessed on May 23, 2022).

    3. United States Centers for Disease Control and Prevention. https://www.cdc.gov/poxvirus/monkeypox/response/2022/world-map.html (Accessed on June 10, 2022).

    4. Mauldin MR, McCollum AM, Nakazawa YJ, et al. Exportation of Monkeypox Virus From the African Continent. J Infect Dis 2022; 225:1367.

    5. United States Centers for Disease Prevention and Control. Monkeypox: monitoring people who have been exposed. https://www.cdc.gov/poxvirus/monkeypox/clinicians/monitoring.html#exposure (Accessed on May 24, 2022).


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