A mutated strain of the clade 1 virus has been discovered in Kamituga
– a poor and densely packed gold mining town.
CREDIT: STRINGER/AFP
Mutated strain of mpox with ‘pandemic potential’ found in DRC mining town
April 16, 2024
A concerning new strain of mpox with “pandemic potential” has been found in a mining town in the Democratic Republic of Congo, according to new research.
The paper – a pre-print which has not yet been peer-reviewed, but is being pored over by global experts – calls for “swift action” from the international community if another international mpox outbreak is to be averted.
Mpox sparked a global epidemic in 2022, when it spread to more than 100 countries, predominantly affecting gay and bisexual men. But the DRC is struggling to control a much deadlier form of the virus, known as “clade 1”, which kills up to 10 per cent of those infected.
Last year, the central African country faced an unprecedented outbreak, and that looks set to continue: in the first quarter of 2024 alone, 3,576 people were infected and 264 killed, according to the World Health Organization (WHO). Two thirds of cases and 85 per cent of fatalities were among children.
Now a mutated strain of this clade 1 virus has been discovered in Kamituga – a poor and densely packed gold mining town with a highly itinerant population just 170 miles from the Rwandan border – where a sudden and unusual mpox outbreak has raised “alarm bells”.
Named “clade 1b”, the virus appears to be better at spreading between people, predominantly via sexual contact, and has mutations that evade detection by some existing tests.
“Without intervention, this localised Kamituga outbreak harbors the potential to spread nationally and internationally,” say the authors, who tracked 241 suspected and 108 confirmed cases of the new strain.
“Given the recent history of mpox outbreaks in DRC, we advocate for swift action by endemic countries and the international community to avert another global mpox outbreak,” they wrote.
The outbreak in Kamituga, which is described as having “pandemic potential”, raises unnerving questions: not only has the virus never been reported in the region before, but – unusually – it is spreading in an urban hub and predominantly infecting adults, especially sex workers.
“We’re seeing evolutionary changes within the virus that’s suggestive of increased human transmission… and we’re seeing the changing demographics in this one specific region of Congo,” said Dr Jason Kindrachuk, an associate professor in infectious disease at the University of Manitoba in Canada and co-author of the paper.
“This is very important, because it’s suggestive of a change in the epidemiology [distribution] of the disease,” he told the Telegraph.
‘This is a global issue’
New mpox strains are relatively rare. But while clade 1b is still responsible for a very small proportion of cases in the DRC, Dr Kindrachuk added that the discovery is reminiscent of another mutation which appeared in clade 2 mpox in 2017.
It was then that indications of sustained human to human transmission, including through sexual contact, was first detected - but the trend was largely overlooked. Then, the virus exploded internationally in May 2022.
“This is an increasing alarm bell for why we need to get vaccines and therapeutics deployed in the DRC,” he said. “This is not just a Congo-centric issue, this is not just a sub Saharan Africa issue, this is a global issue. As we saw in May 2022, we’re all interlinked.”
The pre-print warns that the “local healthcare infrastructure is ill-equipped to handle a large-scale epidemic”, and calls for urgent action – including surveillance, contact tracing and targeted vaccinations – to halt the spread of the new stain.
It says there is a “substantial risk of outbreak escalation beyond the current area and across borders” because the mutations have emerged within a “highly mobile” population. People, including miners and sex workers, frequently travel to Kamituga for work, including from nearby Rwanda and Burundi.
Mpox has a long history in the DRC, with the first known human case detected in a nine-year-old boy in northwest DRC in 1970. But outbreaks have accelerated in recent years, as the country’s population has swelled and pushed into the rainforest basin.
Researchers say this – plus a fall in immunity as protection from smallpox vaccine has waned – could be driving more spillover events from wildlife, which remains a major route of infection.
Chains of transmission do happen – mpox can spread through contact with the infectious skin lesions and blisters that erupt across a person’s body when they contract the disease – but have until recently been limited, especially for clade 1.
The Kamituga outbreak appears to be the largest sustained spread via sexual contact reported in the DRC, though it is not the first time that this has been an detected. Last November, the WHO confirmed this transmission route in Kwango – a province in western DRC some 1,200 miles away from Kamituga.
But the latest paper, which tracked 241 suspected cases reported between October and February, found transmission was “primarily linked to sexual contact”.
This finding is in line with a smaller investigation into the Kamituga cluster, published as a pre-print in March.
Contradicting the general transmission patterns in the DRC, the average age of those infected was 22, while half of patients were women, and 29 per cent were sex workers.
Some 85 per cent of people had genital lesions, while 10 per cent were bedridden in hospital and two people died.
“The sexual transmission piece is a million dollar question,” said Dr Kindrachuk. “We picked up on it in 2023, but we now need to look at this and say: okay, do we have an alternative route of transmission from what we’ve historically seen? How long has this been occurring? And have we been missing cases?”
He added that, when combined with the mutations, this new transmission route will “really complicate” efforts to curb mpox transmission. But it is not yet clear whether the clade 1b has the same fatality rates as clade one, especially as it is so far affecting adults more than children.
The paper was discussed by the ministers of health of 12 countries at a meeting convened by the Africa Centres for Disease Control last week.
“[We are] seriously concerned about the changing transmission dynamics, high mortality rate and transmissibility of themonkeypox virus, as well as the morbidity, mortality and social and economic impacts,” officials said in a statement concluding the conference.
The latest pre-print – which was led by Congoleses scientists in collaboration with experts across Africa, Europe and North America – suggests clade 1b emerged sometime between July and September 2023, after a new spillover from animals.
It’s not clear why this happened in Kamituga, but the virus then picked up new mutations as it circulated in people, especially via sexual networks.
“[This] is a good example of how we risk having periodic zoonotic infections lead to sustained human to human transmission (much like our H5N1 concern), if not better curtailed and addressed,” said Prof Megan Coffee, an infectious disease physician and researcher at Columbia University’s Mailman School of Public Health, who was not involved in the study.
“Over time mutations may better allow for human to human spread,” she told the Telegraph. “Basically, I would say that although mpox has been pushed back in much of the world, mpox is not over.”
But Dr Tom Fletcher, an infectious disease specialist at the Liverpool School of Tropical Medicine, stressed that further studies in larger cohorts are needed to establish whether it is as severe as the original clade one virus.
“In terms of increased risk of spread to other countries – as always the best way to prevent this is to enable this to be controlled at source. Ultimately though, if high case counts remain in DRC and extend through Africa, we’ll see more exported cases,” he said.
Prof David Heymann, a former WHO executive who worked on the DRC’s mpox response in the late 1970s, added: “The authors report what appears to be an amplification of human to human transmission of mpox due to contact with lesions among sex workers and their clients.
“They also present data that suggests the animal origin of initial infections, reminding us that mpox is endemic in an animal reservoir in nature [which is] yet to be identified. As for any emerging infection with amplified transmission, the final outcome of increased human to human transmission is not at present known,” he told the Telegraph.
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