Background:

• 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. Photo: CDC

Transmission:

• 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.

Management:

• 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.

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).