Health officials around the world have sounded the alarm about a variant of MPOX circulating in the Democratic Republic of Congo, but little is known about it other than that it appears to transmit more easily between humans.
The MPOX virus circulating in North and South Kivu provinces of the Republic of Congo is believed to have mutated from a lineage endemic to Central Africa (lineage I) and is distinct from strains derived from lineage II that affected the United States and other Western countries in 2022-2023.
According to the World Health Organization (WHO), the MPOX-related risk in Congo remains high, with the recently identified MPOX strain estimated to have emerged around September 2023.
While much remains unknown, the virus appears to have some worrying characteristics.
“The main difference, and what we can see in the epidemiology, is that there is sustained human-to-human transmission. This has been going on for months and, in terms of lineage I, it’s really new,” said Sylvie Joncaire, an emerging infectious diseases adviser for Doctors Without Borders, now based in Goma, Republic of Congo.
Clade I mpox spreads primarily from animals to humans as a zoonotic disease and is thought to be associated with a higher mortality rate than clade II, with up to 10 percent of infected individuals dying.
The WHO noted that strains descended from lineage I have mutations that indicate “viral adaptation through human circulation.” Unlike COVID-19, the MPOX virus is not known to mutate rapidly.
William Schaffner, a spokesman for the National Foundation for Infectious Diseases, said MPOX is similar to measles in that it is prone to mutations, but a single vaccination usually provides lifelong protection.
“Certainly, we’ve never documented an outbreak, a pandemic of MPOX like we’re seeing now. There have been sporadic cases, of course, but nothing like this,” Schaffner said. “This is a very unusual outbreak. It doesn’t seem to be a virus that mutates easily, but we’ve seen things that give us confidence that it’s the result of a mutation.”
Unlike MPOX, which spread to Western countries in 2022, the new strain does not appear to be strongly linked to sexual transmission or to social networks of gay men.
About 25 percent of cases occur in children, Joncaire said, but the MPOX virus that is prevalent in eastern Congo does not appear to cause more severe disease.
“The fatality rate is actually not that severe. The fatality rate of the disease in eastern Congo is quite low so far compared to what we’ve seen. [Equatorial Guinea]both historically and more recently,” Joncaire said.
Media such as BBC It has been reported that the mpox variant may be “the most dangerous one to date.” Joncaire said it depends on “how you define ‘dangerous,'” noting that the current lack of comprehensive information on the variant means “we need to take it with a pinch of skepticism, maybe even a little more than a pinch of salt.”
“It looks like it’s likely to be transmitted from person to person, so wherever people go, the virus follows them,” she said. “In this part of the Congo, there’s a lot of travel between countries, so it could spread further. But if you look at the death tolls, the mortality rate, etc., it’s not that dangerous. So it really depends on how you define the virus.”
One of the factors hindering the spread of infection is the inability to maintain adequate social distancing.
“There is no option for distancing in any form. There are literally seven people living in a four-square-metre shelter,” Joncaire said, pointing to other factors that exacerbate the spread of MPOX in the area, including a lack of clean water and sexual and business contacts.
At present, this MPOX strain appears to be confined to Congo, but the area shares borders with both Burundi and Rwanda, creating opportunities for transmission abroad.
Joncaire noted that the infection is being assessed as a regional threat.
Vaccination efforts are underway in Congo, and Schaffner noted that the smallpox vaccine used in the United States during the 2022 smallpox outbreak should still be effective against the mutant strain.
MPOX is no longer considered a public health emergency in the United States, but the WHO still considers it to be a “moderate” threat in historically affected countries and neighboring countries. The general population of countries not affected prior to the outbreak that began in 2022 is considered to be at low risk.
The WHO’s June report listed 646 laboratory-confirmed cases of all types of MPOX reported from 26 countries in May, an increase from the previous month.
Since 2022, reports of the virus have declined, and current estimates of the number of infected people are believed to be underestimates.
“It continues to be a concern, I mean, the epidemic curve started to increase, peaked, and then it went down significantly, but it never went away,” Schaffner said. “I don’t think there have been any reports in neighboring countries, and there have been no reports so far of export to Europe, Canada, the U.S. or anywhere else. But obviously, public health officials are monitoring this very diligently because that’s a possibility.”
