Mpox Guidance for Clinicians

Please Note: This page is currently being updated.


Mpox (formerly Monkeypox) is an orthopoxvirus endemic to western and central Africa, with outbreaks in the Western Hemisphere attributed to international travel and the exotic pet trade. Mpox viruses are separated into two clades, I and II, and clade II is further subdivided into IIa and IIb. Clade I viruses may cause up to 10% human mortality, while clade IIa and IIb members have a markedly lower reported mortality rate with a much higher infectivity rate (R0). The global mpox outbreak began in May 2022 with a clade IIb virus. 

Table of Contents

Mpox Presentation

Typical Symptoms

Non-rash symptoms: 

Fever, chills, myalgia, arthralgia, fatigue, headache, backache, sore throat, and cough are common symptoms in mpox infection2. 

Rash or lesions2,7–9 

Mpox lesions often begin at the site of inoculation but may appear in other locations as well. Anogenital, oropharyngeal, perioral, palmar, and plantar regions are commonly affected and require special attention, though other areas like the face and trunk may also be affected. Progression often—though not always—develops from macules, papules, vesicles, and pustules prior to crusting and falling off, allowing for new, healthy skin epithelialization. They may appear necrotic at the endstage. Lesions will commonly be well-circumscribed, umbilicated, and rubbery in appearance and localized and discrete in area. A typical mpox infection will result in less than 50 lesions and may result in atrophic or hypertrophic scarring. 

Severe Symptoms

Atypical signs and symptoms of mpox infection10 

        • Hemorrhagic disease
        • Necrotic rashes and disseminated rashes affecting several areas around the body, such as anogenital region, face, and oropharyngeal region
        • Confluent rashes
        • Secondary bacterial infection due to scratching lesions and septicemia
        • Encephalitis
        • Myocarditis
        • Pulmonary complications: pharyngeal and laryngeal lesions may, rarely, lead to airway compromise
        • Severe, potentially obstructive lymphadenopathy
        • Ocular and periorbital infections
        • Proctitis: may become severe such that bowel function is disturbed
        • Urethritis
        • Other conditions requiring hospitalization

While not as common, mpox can feature severe complications and death. While anyone with mpox may experience severe symptoms, certain people (listed in “Severe symptoms: Groups at high risk of severe mpox symptoms”) are more likely to experience severe symptoms or complications and may require more substantial care. 

Groups more likely to experience severe mpox symptoms

        • Individuals with immunocompromising conditions
        • People with active disease targeting the skin, such as atopic dermatitis, eczema, and herpes simplex
        • Children under one year old
        • Pregnant or breastfeeding persons


Symptom presentation is variable 

Mpox infection is typically self-limited and lasts two to four weeks. Patients may present with some, all, or none of these symptoms. Asymptomatic presentation is rare but has been found in some patients. Some lesions, particularly those in the anogenital region, may be difficult to identify. 

In previous mpox outbreaks, flu-like prodromal symptoms were the predominant initial symptoms. In the global outbreak, patients often presented with only rash; about half presented with a non-rash viral prodrome.3,4,8,11,12


Guidance for physician communication with public health laboratory services for mpox cases

Regardless of vaccination history, physicians should consider contacting their local public health unit and/or Public Health Ontario for contact tracing based on mpox case classification—namely: confirmed, probable, and suspected cases as well as persons under investigation. This is further discussed in the “Diagnosis: The likelihood of mpox infection” and “Diagnosis: Contact tracing and Ontario Public Health” sections.13 

Mpox transmission

Mpox is transmitted through human-to-human contact and other mammalian exposure. Prolonged skin-to-skin contact (particularly, rash or lesion exposure), respiratory secretions, fomites, and childbirth, both intra- and postpartum, are all potential modes of mpox transmission. While mpox virus DNA has been detected by polymerase chain reaction (PCR) in semen (up to 54 days after illness onset), urine, conjunctival fluid, blood, plasma, serum, feces, and vaginal fluid, they have since not been epidemiologically supported as sources of transmission. Further, determination of infectivity via bodily fluids such as saliva or semen are challenging due to skin-to-skin contact potentially confounding any results generated. 

With an average estimated incubation period of seven days (range, three to 21 days), transmission is possible up to three days prior to symptom emergence. Conversely, there is currently no evidence to support that asymptomatic carriers may pass the virus on to others. A person is deemed non-infectious once every lesion has fallen off with subsequent re-epithelialization—alongside the cessation of non-rash symptoms.6,7,14,15 

Epidemiology of the global outbreak

During the recent global outbreak, transmission has disproportionately affected sexually active gay, bisexual, pansexual, and other men who have sex with men (gbMSM) as well as trans women who have sex with men, as outlined in the following links:

Transmission among these people has primarily occurred through intimate and sexual contact with new and multiple partners.  

While most reported mpox transmission has occurred via sexual contact among gbMSM, anyone may contract mpox through skin-to-skin contact, respiratory droplets, fomites, and intra- and postpartum contact. There are no reported cases of intrapartum, postpartum, or human-to-animal transmission in North America during the global outbreak.4,16–19  

Related resources to check out

12 September 2023

Ontario’s Mpox Awareness Campaign Evaluation: Final Report

6 September 2023

GHB awareness resources