Mpox virus

Current situation

On August 14, 2024, the World Health Organization (WHO) declared the spread of mpox virus clade I on the African continent a Public Health Emergency of International Concern (PHEIC). The Public Health Agency of Canada (PHAC) considers the likelihood of importation of clade I mpox to Canada to be low to moderate and considers the risk to Canadians to be low. The current risk to Alberta is also considered low.

Overview

Strains

There are 2 different strains of the virus known as clades (clade I and clade II).

Clade I

• Clade I is endemic in the Democratic Republic of the Congo (DRC) where there is an ongoing mpox outbreak.  
• Current reports suggest clade I can cause more severe illness and death, compared to clade II.

Clade II

• A previous outbreak declared by the WHO in 2022-2023 involved global spread of mpox clade II. 
• Cases of clade II mpox were reported across Canada, including 44 infections reported in Alberta in 2022 and 3 cases in 2023. 

Signs and symptoms

Mpox infection is usually a mild illness that resolves without treatment. Most people recover within several weeks, however severe illness can occur in some individuals.

Signs and symptoms can vary and do not always present in order. The illness may also not present the same in every case.

The risk to the public, including children, is low. Children presenting with rash illness would not be considered to be at risk for mpox unless they have risk factors such as a known close contact exposure to a confirmed case, for example a household member. They should be investigated for more common causes of rash.

Symptoms

Symptoms can develop 5 to 21 days after exposure to the virus and generally begin with:

• fever
• chills
• swollen lymph nodes
• headache
• muscle pain
• joint pain
• back pain
• exhaustion

Rash

Within one to 3 days after the fever starts, a rash may start on the face and then spread elsewhere on the body. In some cases, the rash may occur without flu-like symptoms or flu-like symptoms may occur after the rash appears. The rash can affect:

• mucous membranes in the mouth, tongue and genital area
• palms of hands
• soles of the feet

The rash can last for 2 to 4 weeks and goes through different stages (from skin discoloration to sores to scabs before the scabs fall off).

How it spreads

Mpox does not spread easily between people, but can occur through:

• direct physical contact, including sexual contact, and contact with mpox skin lesions or scabs
• prolonged exposure to respiratory droplets of an individual infected with mpox
• contact with contaminated materials used by an infected person, such as clothing, bedding or towels

Mpox can spread to others from the time symptoms start until the scabs fall off and new skin can be seen, usually 2 to 4 weeks. Scabs contain virus that can spread the illness to others, and should be carefully disposed of.

Treatment and prevention

Most people recover from mpox without treatment. Some people with more serious illness may require hospitalization and supportive care.

Treatment

Treatment options may be available to those at risk of severe illness. Call Health Link at 811 or your health care provider if you think you were exposed to a case of mpox.

• A limited supply of an antiviral drug is available for severe cases and requires consultation with a specialist before it is given.

Prevention

To protect yourself and prevent mpox:

• avoid skin-to-skin or face-to-face contact with anyone who has symptoms
• practice safer sex, use condoms and limit the number of sexual partners you have, especially those who are anonymous
• clean hands, objects and surfaces that have been touched regularly
• don’t share personal items with others
• wear a mask if you are in close proximity with someone who has symptoms
• While travelling, especially to areas where mpox transmission is ongoing, exercise caution if you plan to attend gatherings or events that include close, prolonged and frequent interactions among people, particularly sexual activity. In addition, avoid contact with wild animals.
• Albertans at highest risk (see vaccine eligibility) of exposure should be immunized with a 2-dose series of the Imvamune vaccine. The vaccine is available at no cost to eligible individuals and, contains a modified version of a related virus that cannot multiply or make you sick with mpox.

Vaccine eligibility

Pre-exposure

The Imvamune vaccine is available as a 2-dose series, where eligible individuals should receive their second dose at least 28 days after their first.

The following individuals are eligible for the Imvamune vaccine before exposure to mpox:

• Men who have sex with men (MSM) and who meet at least one of the following criteria:
  • Have more than one sexual partner.
  • Are in a relationship where at least one of the partners has other sexual partners.
  • Have had a confirmed sexually transmitted infection acquired in the last year. 
  • Have engaged in sexual contact in sex-on-premises venues.
• Sexual partners of any of the above.
• Sex workers regardless of gender, sex assigned at birth, or sexual orientation. 
• Staff or volunteers in sex-on-premises venues where workers may have contact with objects or materials potentially contaminated with mpox.
• Individuals who engage in sex tourism (regardless of gender, sex assigned at birth, or sexual orientation).
• Individuals who anticipate experiencing any of the above scenarios.

Note: MSM (men who have sex with men) are defined as any man or Two-Spirit identifying individual who has sex with another person who identifies as a man, including but not limited to individuals who self-identify as trans-gender, cis-gender, 2-Spirit, gender-queer, intersex, and non-binary.

Post-exposure

If given shortly after exposure to mpox, Imvamune vaccine may prevent infection or reduce the severity of illness if infection does occur. If you believe you have been in close prolonged contact with someone with mpox, self-isolate and call Health Link at 811 or your health care provider.

Book an appointment

Eligible individuals who are interested in receiving the mpox vaccine can call Health Link at 1-866-301-2668 to review eligibility and book an appointment.

International travel

Public Health Agency of Canada issued a level 2 travel health notice for mpox for affected countries.

Check for active advisories for your travel destination before you travel outside of Alberta or Canada.

Resources

Government of Alberta

• Mpox fact sheet

Alberta Health Services

• Mpox

Public Health Agency of Canada (PHAC)

• Mpox (monkeypox)
• Mpox: Advice for travellers 

International

• US Centers for Disease Control and Prevention (CDC)
• World Health Organization (WHO)