Mpox virus (formerly known as Monkeypox)

Table of Contents

Mpox (formerly know as Monkeypox) is a rare disease that is caused by infection with Mpox virus. The mpox virus belongs to the Orthopoxvirus genus which also includes variola virus (which causes smallpox), vaccinia virus (used in the smallpox vaccine), and cowpox virus.

Mpox was first discovered in 1958 when two outbreaks of a pox-like disease occurred in colonies of monkeys kept for research, hence the name ‘monkeypox.’ The first human case of mpox was recorded in 1970 in the Democratic Republic of the Congo (DRC). Mpox is thought to originate in rodents in Central and West Africa, and it has repeatedly jumped to humans. Cases outside Africa are rare and have so far been traced to infected travelers or imported animals.

In May 2022, multiple cases of mpox were identified in several non-endemic countries. On July 23, the World Health Organization (WHO) Director General issued a statement declaring that the global mpox outbreak represents a public health emergency of international concern (PHEIC). Following this, the Public Health Agency of Canada (PHAC) also issued a statement to provide an update on the ongoing response to mpox.

There has been an ongoing outbreak of the clade II mpox in Canada since 2022, for which the Public Health Agency of Canada continue to work with provincial and territorial public health partners to investigate cases. As of September 23, 2023 there have been 1,515 cases of mpox in Canada. Some regions of Canada have continued to report cases of the less severe clade II mpox, including a recent uptick of cases in the Toronto area in August 2024.

On August 14, 2024 the WHO declared a public health emergency of international concern as the emergence of a clade I mpox outbreak within the African regions, most notably in East and Central Africa. More than 15,000 mpox cases and 461 deaths were reported in the African content year-to-date, representing a 160 per cent increase from 2023. A total of 18 countries are impacted, with Burundi, Kenya, Rwanda and Uganda recently reporting infections for the first time.

Through its wastewater surveillance program the Public Health Agency of Canada (PHAC) has been monitoring for mpox virus in Canada since July 2022, which includes ability to test for clade I and clade II. Mpox cases detected in provinces and territories are required to be reported to PHAC. To date there have been no cases of clade I mpox virus in Canada.

Government of Canada’s response to the World Health Organization’s declaration on mpox (Aug 14, 2024)
WHO Director-General declares mpox outbreak a public health emergency of international concern (Aug 14, 2024)
WHO Multi-country outbreak of mpox report (Aug 12, 2024)
2022-24 Mpox (Monkeypox) Outbreak:Global Trends (WHO)

Transmission

Historically, there has been limited person-to-person transmission.Monkeypox can spread from animals to humans, from person to person and through contaminated objects.

Mpox is mostly spread through contact with sores or blisters.
It can also be transmitted through items like bedding or towels that have monkeypox virus or respiratory droplets such as coughs and sneezes during close, face-to-face contact with a person who has mpox.
Mpox is not known to be a sexually transmitted infection, like syphilis or HIV, but sexual activities often include close contact.

Signs and Symptoms

According to the World Health Organization, all of the infected people in the U.K. contracted the West African clade of the virus, a version that tends to be mild and usually resolves without treatment. Most people experience symptoms that last 2 to 4 weeks and occur in two stages. The infection begins with fever, headache, aching limbs and fatigue. Other less common symptoms can include sore throat, cough, nausea or vomiting, and diarrhea. Typically, after one to three days, a rash develops, along with blisters and pustules that resemble those caused by smallpox, which eventually crust over.

The second stage usually starts 1 to 5 days after the first stage. Rash (sores/blisters) develop. Mpox sores/blisters are most commonly seen on the hands, feet, arms, legs, mouth and/or genitals. Mypox sores/blisters usually last between 2 to 3 weeks. The rash change in appearance over time from raised spots to small blisters filled with fluid. They eventually form a scab and fall off.

Mpox (Monkeypox) National Case Definition

Suspected case

A person of any age who presents with one or more of the following:

An unexplained acute rash AND has at least one of the following signs or symptoms
- Headache
- Acute onset of fever (>38.5°C),
- Lymphadenopathy (swollen lymph nodes)
- Myalgia (muscle and body aches)
- Back pain
- Asthenia (profound weakness)
An unexplained acute genital, perianal or oral lesion(s)

Probable case

A person of any age who presents with an unexplained acute rash or lesion(s)

AND

Has one or more of the following:

Has an epidemiological link to a probable or confirmed mpox case in the 21 days before symptom onset, such as
- face-to-face exposure, including health workers without appropriate personal protective equipment (PPE)
- Direct physical contact, including sexual contact; or contact with contaminated materials such as clothing or bedding
Reported travel history to or residence in a location where mpox is reported in the 21 days before symptom onset.

Confirmed case

A person who is laboratory confirmed for mpox virus by detection of unique sequences of viral DNA either by real-time polymerase chain reaction (PCR) and/or sequencing.

Source: Public Health Agency of Canada

Infection Prevention and Control

PPE used by healthcare personnel who enter the patient’s room should include:

Gown
Gloves
Eye protection (i.e., goggles or a face shield that covers the front and sides of the face)
NIOSH-approved N95 filtering facepiece or equivalent, or higher-level respirator

Resources

Date Modified: August 16, 2024