Mpox update
Mpox (formerly known as monkeypox) is an infectious disease caused by the monkeypox virus, that causes symptoms similar to, but less severe, than smallpox. An increase in mpox (clade II) activity has been observed in Ontario since mid-January 2024 and the WHO has recently (Aug. 14, 2024) declared a public health emergency of international concern due to an outbreak of mpox (clade I) in the Democratic Republic of the Congo and neighbouring countries.
Early detection and management of mpox is of critical importance. Consider mpox as a diagnosis in individuals presenting with signs and symptoms that may be compatible, especially with those with history of travel to affected countries, close contact with a known case, or other risk factors.
Public health units are encouraging health care providers (HCPs) to test individuals with compatible clinical evidence for mpox, and to promote a two-dose Imvamune vaccination series to eligible patients with a reminder that previous smallpox vaccination may not be protective against mpox infection, and they should receive Imvamune even if previously vaccinated for smallpox.
HCPs are reminded to obtain contact information from every client who is a probable or suspect case and refer to HPEPH Infectious and Communicable Diseases (ICD) at 613-966-5500, ext. 349 for follow-up and contact tracing.
Symptoms
Mpox symptoms include, but are not limited to:
- Rash or lesion(s) to the hands, feet, chest, face, or mouth, or to the genitals and anus (may resemble chicken pox)
- Fever
- Headache
- Muscle aches
- Fatigue
- Respiratory symptoms (sore throat, nasal congestion, cough)
- Lymphadenopathy
HCPs should keep mpox on their differential diagnosis and have a low threshold to test in high-risk patients with compatible signs and symptoms. Mpox is typically mild and self-limiting but can cause severe illness in some individuals.
Transmission
The main routes of transmission are:
- Close contact, especially sexual contact, providing care, and living in the same household
- Direct contact with skin lesions/scabs, blood, bodily fluids, and mucous membranes
Other less common routes of transmission include:
- Respiratory
- Contact with contaminated materials - bedding, linens, towels, lesion dressings or needles
Testing
Potential cases should be assessed for appropriate differential diagnoses based on their clinical presentation and tested using the Public Health Ontario testing protocols in the appropriate clinical setting based on severity including within primary care settings or emergency departments. Potential cases should contact their HCP with advanced notice to allow for the necessary precautions to be taken as per PHO IPAC Recommendations for Mpox in Health Care Settings, e.g., individual with suspect or confirmed mpox is to be placed in a single-patient room with the door closed. Precautions should be taken to minimize exposure to surrounding individuals such as having the patient don a medical mask over their nose and mouth, for source control, as tolerated, and covering exposed skin lesions with clothing, sheet, or gown as best as possible.
Vaccination
- Imvamune is a two-dose series, given 28 days apart. Booster doses are not recommended.
- Patients should be encouraged to receive the full two dose series to protect against mpox. Recent studies have shown vaccine effectiveness to be between 66 to 83 per cent for patients with a two-dose vaccine series.
- Imvamune should be considered for the following:
- Pre-exposure vaccination – individuals at high risk of mpox exposure
- Post-exposure vaccination – individuals who have had a high-risk exposure to a probable or confirmed case of mpox, or within a setting where transmission is happening.
- First dose should be offered as soon as possible, ideally within four days (up to 14 days) from date of last exposure to individuals who are a high-risk contact of a confirmed/probable case of mpox
- A second dose should be offered 28 days after the first dose if mpox infection did not develop, regardless of ongoing exposure status
- Due to limited supply, Imvamune is currently only being administered by HPEPH
- Eligible patients for pre- and post-exposure vaccination can be directed to book an appointment with the HPEPH Sexual Health Harm Reduction team at 613-966-5500, ext 243.
Additional information about Imvamune Vaccine is available in the following documents:
Additional information about mpox is available at:
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