Where does the mpox virus come from?
Since it was first identified in 1958 in Denmark, this virus, a cousin of human smallpox, has had several names. It was first dubbed “monkeypox,” because it was found in a colony of monkeys in a Copenhagen laboratory whose individuals had skin lesions similar to human smallpox. But the name is misleading, says Dr.D Judith Fafard, medical director of the Quebec Public Health Laboratory, “because monkeys are not the primary reservoir of the virus.” In fact, it is rodents that transmit the disease to humans.
Moreover, in 2022, during the last resurgence of the virus, the name of the disease was changed to avoid stigmatizing the victims. English speakers shortened the form “monkeypox” to “mpox”, and the French-speaking world adopted “variole simienne”, a term that nevertheless still refers to monkeys. “More and more, even in French, we use the name mpox”, says Dr.D Fafard.
What kind of virus is it?
It is a virus that belongs to the poxvirus family (which attacks both humans and animals) and the orthopoxvirus genus, with which smallpox is associated. Human smallpox, which was named so because of the pustules (variolain Latin) that the infection causes, was officially eradicated in 1980 thanks to vaccination.
It is likely that the cessation of human smallpox vaccination has contributed to zoonotic outbreaks in African countries.
DD Judith Fafard, medical director of the Quebec Public Health Laboratory
Two types of MPOX have been identified: clade I (which circulates in the Congo Basin) and clade II (more present in West Africa). While transmission was previously very limited – an infected person would only transmit the virus to a very small circle of relatives – a mutation of clade II has led to more sustained transmission starting in 2022. In Quebec, 527 cases had been identified in 2022.
This time, it is clade I that is gaining strength. A new subtype, clade Ib, is circulating in Burundi, Kenya, Rwanda, Uganda and especially in the Democratic Republic of Congo (DRC), which has recorded 16,000 of the 18,000 cases recorded this year.
PHOTO GUERCHOM NDEBO, ARCHIVES AGENCE FRANCE-PRESSE
A doctor talks with patients on Saturday outside the Mpox treatment center at Nyiragongo General Hospital, north of Goma, DRC.
“The virus has been raging for several months in the region of [sud du] Kivu, where there are many camps for displaced people due to the civil war, sanitary and accommodation conditions that can promote the transmission of a virus that is contagious when in close contact with people who are infected,” notes Dr.D Fafard.
The first case of clade Ib outside Africa was identified in Sweden last week. On August 14, the World Health Organization (WHO) declared a public health emergency of international concern, the highest level of health alert.
What is the difference between the two types of mpox?
The symptoms and level of contagion are essentially the same: fever, pain, formation of papules that become pustules. The infection usually disappears on its own within two to four weeks. A painkiller may be prescribed.
In the most severe cases, complications include breathing problems, dehydration, difficulty feeding, and, more rarely, death.
The big difference is that clade I mpox infections have more complications than clade II infections. The mortality rate for clade I is 4% in the general population (11% in children), while it is less than 1% for clade II. Of the 16,000 cases identified in the DRC this year, 548 have been fatal.
How is the virus identified?
In Quebec, the practitioner who suspects a case of MPOX takes a sample that will be analyzed in a laboratory. On average, about ten samples of suspected cases are sent each week, says Dr.D Fafard, but only 10 cases have been confirmed since the beginning of the year. MPOX pustules are sometimes confused with herpes, ulcers, shingles or other staph infections.
In Canada, 164 cases of MPOX have been identified this year, all of clade II. The Toronto area alone had counted 93 cases by the end of July.
Who is at risk of contracting the virus?
The virus is transmitted primarily through skin-to-skin contact, sexual contact, or droplets of the spittle type (not microdroplets dispersed through the air).
In 2022, several infections had been identified among members of the LGBTQ+ community, and a targeted information campaign had been launched. This time, in African countries affected by clade Ib, the virus is circulating in heterosexual environments and particularly affects children, who are likely to have close contact with infected adults.
Is there a vaccine?
Yes, and it is currently offered in Quebec to people targeted by public health authorities – those who frequent settings where transmission has been confirmed. Children are not part of the targeted populations. “The children at risk right now are those who live in camps in [sud du] Kivu,” says DD Fafard.
“Right now, there is nothing to say that children in Quebec and Canada will be at greater risk of catching the virus. We are monitoring what is happening to see if we need to make adjustments, but as we speak, clade I is not circulating in Canada.”
African health officials have asked Canada to donate part of its vaccine supply to help stop the disease at its source. On Monday, Canada announced $1 million in support to the WHO to improve detection and reporting systems for the disease.
Read “Mélanie Joly announces a donation of 1 million to fight MPOX”