Mpox Information for Health Professionals

In November 2024, Canada confirmed its first case of clade I mpox. This case was linked to the ongoing outbreak in central and eastern Africa. The risk from clade I remains low. The mpox vaccine is not available to travellers unless they meet the eligibility criteria.

 

Mpox (formerly known as monkeypox) virus is an orthopoxvirus that causes a disease with symptoms similar to, but less severe than, smallpox and is endemic to parts of Central and West Africa. There are two clades (subtypes) of mpox: clade I and clade II. Human infections with clade I are typically more severe and have a higher case fatality rate . Illness with clade II is usually self-limiting within two to four weeks with a case fatality rate around one to three per cent.

NOTE: If you see a patient with suspected or confirmed mpox, please ask them to self-isolate and share TPH’s mpox self-isolation guidance with them.

In 2022, clusters of clade IIb mpox virus cases which were not linked to direct travel to Central or West Africa were documented in many countries where mpox is not endemic. Current epidemiological analysis suggests that these infections were spread via close physical contact with an individual who was infectious with mpox, and many (but not all) cases self-identified as men who have sex with men (MSM).

In December 2023, the USA CDC issued alerts to inform health care providers of an accelerating mpox epidemic in the Democratic Republic of the Congo, including the first documented occurrence of sexually transmitted clade I mpox. Clade I has previously been observed to be more transmissible and to cause more severe infections than clade II. In August 2024, the World Health Organization declared the increase of mpox cases in Africa and the emergence of a new strain (clade Ib) a public health emergency of international concern. In November 2024, Canada confirmed its first case of clade I mpox. This case was linked to the ongoing outbreak in central and eastern Africa.

The strain circulating in Toronto is clade II. The introduction of clade I mpox virus in Toronto is possible, however, the risk remains low. To view the latest data on mpox in Toronto, visit Public Health Ontario’s (PHO) Mpox webpage and click on the latest Summary Report.

Prior to the 2022 clade IIb outbreak, mpox infections had been thought to follow a fairly typical pattern, as outlined below. However, some jurisdictions with new outbreaks of mpox have noticed atypical presentations which may include:

The rash may occur before, with or without febrile systemic illness. Initial lesions may appear at sites of inoculation, such as the face and neck with kissing, and the penis and perianal region with sexual exposure. Lesions display pleomorphism, presenting in various stages simultaneously. Vesicles and pustules may be smaller than classically described, sometimes noticed only with surrounding pain, pruritis or erythema. Complications have been reported, including myocarditis, proctitis and epiglottitis.

Typical Presentation:

  • Incubation period (usually six to 13 days, but can be five to 21 days)
  • Prodrome phase (one to three days): occurs prior to onset of rash, or at the same time
    • May involve fever, chills, headache, myalgia, fatigue, backache, sore throat and cough.
    • Lymphadenopathy may occur during the prodrome phase and would be unusual in other diseases that may have similar types of rash (such as chickenpox, syphilis and HSV).
  • Rash phase
    • Typically begins on the face.
    • May then spread to body, extremities, anogenital area, palms, and soles of feet.
    • Typical lesions can be described as deep-seated and well-circumscribed, often with central umbilication.
    • Lesions typically progress through the following stages: macules, papules, vesicles, pustules, and finally scabs.
    • Rash may be localized or generalized. If generalized, it may be similar to smallpox, with a centrifugal distribution.
  • Recovery
    • Rashes scab, fall off, and new skin forms.

Differential diagnosis:

This includes, but is not limited to:

  • chickenpox/herpes zoster,
  • herpes simplex virus-1/herpes simplex virus-2,
  • primary syphilis (with a painless chancre)/ secondary syphilis (with widespread rash),
  • Hand-foot-and-mouth disease,
  • molluscum contagiosum,
  • chancroid.

For distinguishing infectious causes of vesicular lesions see a case of human mpox in Canada.

Mpox is spread to people through direct contact with the bodily fluids or lesions of infected animals or people, via respiratory droplets from an infected person, or from mother to fetus. It can also be transmitted indirectly through contact with materials contaminated with the virus, such as bedding and clothing.

Period of Communicability

Mpox can spread during the prodromal period, but generally starts with the onset of rash until all lesions have crusted, fallen off, and new skin has formed (about two to four weeks). Recent evidence suggests that some individuals may be infectious up to four days before the onset of symptoms.

On January 27, 2025, the Public Health Ontario Laboratory (PHOL) implemented a new assay that can differentiate between the 3 mpox virus clades Ia, Ib and II. Refer to PHO’s Mpox Virus Test Information Sheet for up to date information on who to test and sample collection and submission.

Transporting Mpox Samples for Laboratory Testing

  • Mpox specimens require the same packing and transportation/courier systems that are used for other microbiological testing in outpatient settings.
  • The key difference for mpox specimen transportation is that the transport container must be marked using a contrasting background with “TU 0886” (see Appendix 1 for a printable copy of this label).
  • The same laboratory courier systems that currently pick up specimens from primary care clinical practice locations for microbiology testing can be used for transporting mpox specimens.

More information:

In addition to routine practices, the following measures are recommended for health care workers when interacting with individuals with suspected, probable, or confirmed mpox infection:

  • Place the individual with suspect, probable, or confirmed mpox infection in a single patient room, with the door closed. Inpatients should be placed in a single-person room with a dedicated bathroom.
  • Perform hand hygiene as per the four moments of hand hygiene.
  • Use recommended personal protective equipment (PPE) such as gloves, gown, eye protection (e.g., face shields, safety glasses or goggles), and a fit-tested and seal-checked N95 respirator (or equivalent); perform seal check after donning N95 respirator.
  • Ensure patients wear a well-fitting medical mask.
  • Perform routine environmental cleaning and disinfection and ensure all horizontal surfaces that may be touched by the patient and equipment that may have been used by or shared between patients are cleaned and disinfected after every use. Special and/or additional environmental cleaning and disinfection measures are not required.

More information:

Tecovirimat (TPoxx®) is authorized for sale and use in Canada, for the treatment of human smallpox disease in adults and pediatric patients weighing at least 13 kg based on limited clinical testing in humans. TPoxx® does not have an approved indication for the treatment of mpox in Canada. However, a licensed health care professional may request this drug for eligible patients based on their clinical judgement for treating severe mpox infections.

A limited supply of TPoxx® is available in Ontario for individuals who are severely ill/disabled due to mpox infection or at high risk for severe disease.

Eligibility Criteria

  • Hospitalized patients with severe disease (e.g., hemorrhagic disease, sepsis, encephalitis, myocarditis, esophagitis, or other conditions requiring hospitalization).
  • Persons who may be at high risk of severe disease:
    • Persons who are severely immunocompromised (e.g., individuals with HIV with current CD4 counts < 200/mm3 or with uncontrolled viral loads; receiving active treatment for solid tumour or hematologic malignancies such as chemotherapy, targeted therapies, or immunotherapy; recipients of solid-organ transplant and taking immunosuppressive therapy; recipients of hematopoietic stem cell transplant within two years of transplantation or taking immunosuppression therapy; autoimmune with immunodeficiency as a clinical component; on treatment with agents such as tumor necrosis factor or high-dose corticosteroids);
    • Pediatric populations, particularly patients younger than 10 years of age
    • Pregnant or breastfeeding women
    • Persons with one or more complications (e.g., severe secondary bacterial skin infection; gastroenteritis with severe nausea/vomiting, diarrhea, or dehydration; bronchopneumonia; concurrent disease or other comorbidities).
  • Persons with mpox virus infections with lesions that are leading to significant disability (e.g., proctitis, keratitis or other ocular involvement, pharyngitis/epiglottitis or other breathing/swallowing compromise).

How to Order TPoxx®

Given the limited supply of TPoxx® available in Ontario, TPoxx® should be prescribed based on the eligibility criteria described above.

Health care providers should request TPoxx® by contacting the Office of Chief Medical Officer of Health, Public Health at vaccinesupplyandlogistics@ontario.ca. See Appendix A of the Ministry of Health (MOH) – Mpox Antiviral Guidance for Health Care Providers for the information that needs to be provided as part of the request.

For more information, please refer to the following resources:

    Imvamune vaccine can be used for protection against mpox before getting exposed to the virus (Pre-Exposure Prophylaxis or PrEP) or after being exposed (Post-Exposure Prophylaxis or PEP). The vaccine is effective for both Clade I and Clade II.

    Imvamune is a live-attenuated, non-replicating vaccine which is active against both mpox and smallpox.

    Imvamune should be given as a two-dose series, 28 days apart.

    Note: Imvamune vaccine is not required for health care workers who are seeing patients with mpox infection in their clinical office practice .

    Vaccination clinics

    See TPH’s public Mpox webpage for vaccination clinic information.

    TPH continues to follow federal and provincial guidance on the administration of Imvamune vaccines to protect at-risk populations against mpox virus. Imvamune is not currently available to travellers unless they meet eligibility criteria below.

    Based on the MOH guidelines, the vaccine is available for the following eligible groups:

    For Pre-Exposure Prophylaxis (PrEP)

    1. Two-Spirit, non-binary, transgender, cisgender, intersex, or gender-queer individuals who self-identify as belonging to the gay, bisexual, pansexual and other men who have sex with men (gbMSM) community AND who meet one or more of the following:
      1. Have more than one partner
      2. Are in a relationship where at least one of the partners has other sexual partners
      3. Have had a confirmed sexually transmitted infection (STI) within the last year
      4. Have attended venues for sexual contact (e.g., bathhouses, sex clubs)
      5. Have had anonymous sex (e.g., using hookup apps) recently
    2. Sexual partners of individual who meet the criteria above
    3. Sex workers (regardless of gender, sex assigned at birth, or sexual orientation) or who are a sexual contact of an individual who engages in sex work
    4. Staff or volunteers in sex-on-premises venues where workers may have contact with fomites potentially contaminated with mpox
    5. Individuals who engage in sex tourism (regardless of gender, sex assigned at birth, or sexual orientation)
    6. Individuals who anticipate experiencing any of the above scenarios

    Household contacts of people who are eligible for PrEP listed above AND who are moderately to severely immunocompromised or are pregnant may be considered for pre-exposure vaccination. These individuals should contact a health care provider or TPH for more information.

    For Post-Exposure Prophylaxis (PEP)

    • TPH follows up with all mpox cases and identifies their contacts. Contacts are assessed and, if eligible, are referred to receive Imvamune PEP.
    • People who have a known exposure/close contact with someone with mpox, or an exposure in a setting where mpox is spreading, should contact TPH to find out if the vaccine is recommended to them.
    • PEP should be given within four days but can be given up to 14 days after the last exposure.
    • Individuals should ensure to receive both doses of Imvamune to be best protected.

    Research Laboratory Employees

    • Research laboratory employees working directly with replicating orthopoxviruses are eligible to receive two doses of Imvamune, 28 days apart. These individuals may be offered an additional dose after 2 years if they remain at risk of occupational exposure.

      More information:

      All suspected and confirmed cases of mpox must be reported to TPH by:

      • Completing TPH’s Reportable Disease Notification Form and faxing to 416-392-0047, OR
      • Calling 416-392-7411 during work hours (8:30 am to 4:30 pm, Monday to Friday) or 311 after hours (416-392-CITY (2489) for callers from outside of Toronto)