Mpox Information for Health Professionals

For a concise summary, see Ontario Health’s Testing and Management of Mpox: Information for Primary Care Providers.

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 case fatality rate around 10%. Illness with clade II is usually self-limiting within two to four weeks with a case fatality rate around 1 to 3%. Previously, cases of mpox in countries other than those in Central and West Africa have only been identified as a direct result of travel to these regions.

In 2022, many countries where mpox is not endemic documented clusters of clade IIb mpox virus cases which were not linked to direct travel to Central or West Africa. For more information see the US CDC 2022 Mpox Outbreak Global Map. Current epidemiological analysis suggest 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, PHAC and 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, as mentioned above, to cause more severe infections than Clade II. The introduction of Clade I mpox virus in Canada is possible.

To view the latest data on mpox in Toronto, visit Public Health Ontario’s Mpox webpage and click on the latest Summary Report.

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

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 the 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, but there have been no reported deaths. (A case of human mpox in Canada)

Typical Presentation:

  • Incubation period (usually 6-13 days, but can be 5-21 days)
  • Prodrome phase (1-3 days): occurs prior to onset of rash, or at 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
    • The lesion typically progresses 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. In 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 2 to 4 weeks.

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.

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 N-95 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 healthcare 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

TPoxx® should be considered for the following:

  • 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 2 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®

TPoxx® is provided to clinicians as part of Health Canada’s Special Access Program (SAP). Given the limited supply of TPoxx® available in Ontario, TPoxx® should be prescribed based on the eligibility criteria described above.

TPOXX antivirals should continue to be ordered by clinicians by contacting the Vaccine Policy and Programs Branch at vaccinesupplyandlogistics@ontario.ca.

Health Canada’s SAP has mandatory reporting requirements for clinicians using the Follow-Up Form (Form C), including treatment response outcomes. This form should be returned to the the VPPB at vaccinesupplyandlogistics@ontario.ca. The VPPB will send the forms back to SAP on behalf of the clinician.

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).

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.

Based on the Ontario Ministry of Health guidelines, the vaccine is available for the following eligible groups:

For Pre-Exposure Prophylaxis (PrEP)

  1. Two-spirited, non-binary, transgender, cisgender, intersex, or gender-queer individuals who self-identify or have sexual partners who self-identify as belonging to the gay, bisexual, pansexual and other men who have sex with men (gbMSM) community AND at least one of the following:
    • Had a confirmed sexually transmitted infection (STI) within the last year;
    • Have or are planning to have two or more sexual partners or are in a relationship where at least one of the partners may have other sexual partners;
    • Have attended venues for sexual contact (e.g. bathhouses, sex clubs) recently or may be planning to, or who work/volunteer in these settings;
    • Have had anonymous/casual sex (e.g. using hook up apps) or may be planning to;
    • A sexual contact of an individual who engages in sex work.
  2. Individuals who self-identify as engaging in sex work or are planning to, regardless of self-identified sex or gender.
  3. Household and/or sexual contacts of people who are eligible for PrEP – listed above in parts (1) or (2) – AND who are moderately to severely immunocompromised (have a weak immune system) or are pregnant. 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 as PEP or PrEP if there is an ongoing risk of exposure.

Second Dose Eligibility

  • Based on Ontario Ministry of Health guidelines, everyone eligible to receive Imvamune® as pre-exposure prophylaxis (see eligibility criteria above) can now receive a second dose with a minimum spacing of 28 days.
  • Those that received a single dose of Imvamune® as post-exposure prophylaxis may receive a second dose if the risk of exposure continues beyond or is expected to continue beyond 28 days following their first dose.

More information:

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

  • Completing TPH’s Reportable Disease 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)