Mpox Virus Particle Colorized transmission electron micrograph of an mpox virus particle (yellow and red) found within an infected VERO E6 cell (blue), cultured in the laboratory. Image captured at the NIAID Integrated Research Facility (IRF) in Fort Detrick, Maryland. Credit: NIAID/CC0 Public Domain

A University of Manitoba expert is a vital part of an international team of scientists studying the alarming changes in the spread of mpox across the Democratic Republic of Congo (DRC) to better understand the rapidly evolving virus.

"The expansion of this virus is concerning. Viruses don't have passports. They don't respect international borders. We need to get things under control, " said team member Dr. Jason Kindrachuk, UM Canada Research Chair in molecular pathogenesis of emerging viruses and associate professor of medical microbiology and infectious diseases at the Max Rady College of Medicine, Rady Faculty of Health Sciences.

One of the research team's studies—featured on the cover of The Lancet earlier this year—analyzed 13 years of data and found that mpox has expanded to nearly every region of the DRC. The number of provinces reporting cases has increased from 18 of 26 in 2010 to 24 of 26 in 2023.

"The spread of mpox has changed rapidly over the last couple of years. Cases had been fairly focused within specific regions that were largely rural. Now mpox is a much broader problem across most of the DRC in both urban and rural locations, " said Kindrachuk, an international leader in mpox research who travels regularly to Africa.

Until 2023, Kindrachuk said that most mpox cases were linked to people having contact with wildlife, most likely rodents. The virus also had the greatest negative impact on those under 15 years old, he said.

In a second study published earlier this year in The Lancet, the researchers observed something different in the province of South Kivu. They saw the emergence of a new type of mpox virus, called subclade Ib, which shifted toward sustained human-to-human transmission and an increase in cases among people aged 15 to 34 years old.

Kindrachuk, also a researcher with the Children's Hospital Research Institute of Manitoba, said that among those adults, they had high number of skin and genital lesions, which give the researchers a stronger indication that the cases are likely related to sexual contact. He said many of the people identified as sex workers or those who partake in sex work.

The study also found that the overall disease severity was relatively low in South Kivu. They saw two deaths out of 403 hospitalized patients—a fatality rate of less than one percent.

"The reality is that what we were seeing in South Kivu among those cases was actually different than what we've seen historically, " Kindrachuk said.

Looking back in the past, he said there typically weren't many mpox cases in Kinshasa, the capital of DRC with a population of 17 million. This also changed.

"It's concerning because our research that was published last week in The Lancet shows that it's spreading in Kinshasa. This becomes an even bigger predicament in terms of response efforts because you're not only dealing with spread across the majority of the country, but you also now have it embedded in this very large metropolis that is a major network for many other countries in Africa, " Kindrachuk said.

In a fourth study published in The New England Journal of Medicine in June, the research team found that in three women, mpox was transmitted between mother and baby in utero, resulting in pregnancy loss or infection. The findings support the significance of preventive interventions, including vaccinations, in pregnant individuals, Kindrachuk said.

"We now need to conduct large-scale studies to better understand the outcomes associated with mpox in pregnancy and to help guide clinical management, " he said.

"For us, the complexity is increasing, but all the data that we are identifying in our studies helps inform our response and certainly the actions of other international individuals, organizations and the Congolese on the ground who are leading the response efforts."

More information: Eugene Bangwen et al, Suspected and confirmed mpox cases in DR Congo: a retrospective analysis of national epidemiological and laboratory surveillance data, 2010–23, The Lancet (2025). DOI: 10.1016/S0140-6736(24)02669-2 Isabel Brosius et al, Epidemiological and clinical features of mpox during the clade Ib outbreak in South Kivu, Democratic Republic of the Congo: a prospective cohort study, The Lancet (2025). DOI: 10.1016/S0140-6736(25)00047-9 Tony Wawina- Bokalanga et al, Epidemiology and phylogenomic characterisation of two distinct mpox outbreaks in Kinshasa, DR Congo, involving a new subclade Ia lineage: a retrospective, observational study, The Lancet (2025). DOI: 10.1016/S0140-6736(25)00294-6 Emmanuel Hasivirwe Vakaniaki et al, Three Cases of Vertical Transmission of Clade Ib Mpox Virus, New England Journal of Medicine (2025). DOI: 10.1056/NEJMc2503347  Journal information: New England Journal of Medicine, The Lancet

Brosius et al, Epidemiological and clinical features of mpox during the clade Ib outbreak in South Kivu, Democratic Republic of the Congo: a prospective cohort study, The Lancet (2025). DOI: 10.1016/S0140-6736(25)00047-9 Tony Wawina-

Bokalanga et al, Epidemiology and phylogenomic characterisation of two distinct mpox outbreaks in Kinshasa, DR Congo, involving a new subclade Ia lineage: a retrospective, observational study, The Lancet (2025). DOI: 10.1016/S0140-6736(25)00294-6

Emmanuel Hasivirwe Vakaniaki et al, Three Cases of Vertical Transmission of Clade Ib Mpox Virus, New England Journal of Medicine (2025). DOI: 10.1056/NEJMc2503347