International researchers, including from DTU National Food Institute, warn that the ongoing mpox outbreak in the Democratic Republic of the Congo (DRC) has the potential to spread across borders more rapidly. The mpox virus has mutated, and the new variant, clade 1b, has become more infectious.
Genetic analyses of clade 1b, first detected in September 2023 in Kamituga, DRC, show that this variant has since undergone mutations making it more easily transmissible between humans. Scientists have identified three new subvariants, one of which has spread beyond Kamituga to other cities in the DRC, neighbouring countries, and even internationally to e.g. Sweden and Thailand. The new data may also suggest that clade 1b entails a high risk of miscarriage.
This new research has been published as an accelerated scientific publication in the esteemed journal Nature Medicine.
Originally, mpox was considered a zoonotic disease that primarily spread from animals to humans. However, in 2022, the world witnessed an outbreak primarily affecting men who have sex with men. The new clade 1b differs as both men and women are now contracting the virus. Additionally, an increasing number of infections are being reported among healthcare workers and children.
It’s somewhat like SARS-CoV-2 – the virus undergoes mutations as it spreads. For clade 1b, we see that one particular subvariant appears to have become better at transmitting between humans, and it has now been detected in several countries outside East Africa. In addition, the number of infected pregnant women who miscarry is high among those we have tested.”
Professor Frank Møller Aarestrup from DTU National Food Institute, who leads the GREAT-LIFE project
The GREAT-LIFE project is behind both the discovery of clade 1b and the development of a new PCR test, which enables the detection of clade 1b—undetectable by the original mpox tests.
Call for cross-border collaboration to contain mpox spread
This research indicates that the new variant is spreading rapidly, primarily through heterosexual contact in densely populated areas.
“At present, we are seeing uncontrolled transmission of clade 1b in eastern DRC and Burundi, but to a lesser extent in other parts of East Africa. While there is some international spread, we do not yet expect a large outbreak outside the epicentre in East Africa. However, this situation demands immediate attention. It is crucial to avoid close contact, particularly sexual contact, in high-risk areas,” says Frank Aarestrup.
The spread to neighboring countries underscores the need for expanded cross-border cooperation to track disease transmission, treat patients, and disseminate health education, particularly among sex workers.
“Action is needed locally, including increased vaccination efforts and public awareness campaigns on transmission routes. Additionally, global measures could include travel advisories against visiting high-risk areas and particularly against engaging in sexual contact in affected regions,” says Frank Aarestrup.
The GREAT-LIFE project coincided with mpox outbreak in DRC
DTU National Food Institute coordinates the GREAT-LIFE project, which aims to build capacity for detecting disease outbreaks in East Africa. The project focuses on local implementation of PCR testing for viral diseases using portable equipment. This capacity-building initiative was rapidly tested when, by coincidence, the project launched alongside the emergence of the new clade 1b variant in the DRC.
The mpox outbreak meant that local researchers and healthcare personnel immediately needed the expertise and tools provided by the project. Led by Professor Frank Aarestrup, DTU National Food Institute’s contribution is to equip local researchers with the ability to conduct rapid research and deliver relevant results. As part of its capacity-building efforts, the GREAT-LIFE project has:
- As the first, identified the new variant of the mpox virus: Ongoing mpox outbreak in Kamituga, South Kivu province, associated with monkeypox virus of a novel Clade I sub-lineage, Democratic Republic of the Congo, 2024 – PubMed
- Developed a PCR test to detect clade 1b: Real-time PCR assay to detect the novel Clade Ib monkeypox virus, September 2023 to May 2024 – PubMed
- Tracked and investigated its spread to Burundi: Monkeypox Clade Ib virus introduction into Burundi: first findings, July to mid-August 2024 – PubMed
- Examined the spread in and beyond Kamituga, DRC, as detailed in this article.
Key findings
As of 5 January 2025, more than 9,500 individuals have tested positive for mpox in the Democratic Republic of the Congo (DRC), with an estimated fatality rate of 3.4%. The rapid increase in cases in the South Kivu province of the DRC is particularly concerning.
In this regard, this research shows that:
- The mpox virus has become more transmissible, leading to faster spread.
- Transmission occurs primarily through heterosexual contact.
- The virus spreads through sex workers in densely populated areas.
- There is significant underreporting of cases.
- Mpox infection likely increases the risk of miscarriage in pregnant women.
The researchers have analysed samples from 670 patients infected with mpox. Their findings indicate that 52.4% of those infected were women, while 47.6% were men. The majority of infections were transmitted through sexual contact, but three cases were recorded among healthcare personnel. Seven patients died, and eight out of 14 pregnant women suffered miscarriages.
The research focused on South Kivu province in the DRC, where clade 1b transmission began in September 2023.
About the scientific article
The article has been published in Nature Medicine under a clause allowing rapid dissemination of the findings.
Original title: Epidemiological and genomic evolution of the ongoing outbreak of clade Ib mpox virus in the eastern Democratic Republic of the Congo.
It has been authored by 16 researchers from six different countries: DRC, Rwanda, Denmark, the United Kingdom, Spain, and the Netherlands.
The research has been funded by the EU and EDCTP under the Global Health EDCTP3 grant agreement No. 101103059 (Greatlife project); the EU Horizon 2020 grant VEO 874735; DURABLE (HERA-funded network); Wildlife Conservation Network (WCN); Conservation Action Research Network (CARN); and with support from the Greatlife Mpox Consortium.
Masirika, L. M., et al. (2025). Epidemiological and genomic evolution of the ongoing outbreak of clade Ib mpox virus in the eastern Democratic Republic of the Congo. Nature Medicine. doi.org/10.1038/s41591-025-03582-1.
News
Researchers propose five key questions for effective adoption of AI in clinical practice
While Artificial Intelligence (AI) can be a powerful tool that physicians can use to help diagnose their patients and has great potential to improve accuracy, efficiency and patient safety, it has its drawbacks. It [...]
Advancements and clinical translation of intelligent nanodrugs for breast cancer treatment
A comprehensive review in "Biofunct. Mater." meticulously details the most recent advancements and clinical translation of intelligent nanodrugs for breast cancer treatment. This paper presents an exhaustive overview of subtype-specific nanostrategies, the clinical benefits [...]
It’s Not “All in Your Head”: Scientists Develop Revolutionary Blood Test for Chronic Fatigue Syndrome
A 96% accurate blood test for ME/CFS could transform diagnosis and pave the way for future long COVID detection. Researchers from the University of East Anglia and Oxford Biodynamics have created a highly accurate [...]
How Far Can the Body Go? Scientists Find the Ultimate Limit of Human Endurance
Even the most elite endurance athletes can’t outrun biology. A new study finds that humans hit a metabolic ceiling at about 2.5 times their resting energy burn. When ultra-runners take on races that last [...]
World’s Rivers “Overdosing” on Human Antibiotics, Study Finds
Researchers estimate that approximately 8,500 tons of antibiotics enter river systems each year after passing through the human body and wastewater treatment processes. Rivers spanning millions of kilometers across the globe are contaminated with [...]
Yale Scientists Solve a Century-Old Brain Wave Mystery
Yale scientists traced gamma brain waves to thalamus-cortex interactions. The discovery could reveal how brain rhythms shape perception and disease. For more than a century, scientists have observed rhythmic waves of synchronized neuronal activity [...]
Can introducing peanuts early prevent allergies? Real-world data confirms it helps
New evidence from a large U.S. primary care network shows that early peanut introduction, endorsed in 2015 and 2017 guidelines, was followed by a marked decline in clinician-diagnosed peanut and overall food allergies among [...]
Nanoparticle blueprints reveal path to smarter medicines
Lipid nanoparticles (LNPs) are the delivery vehicles of modern medicine, carrying cancer drugs, gene therapies and vaccines into cells. Until recently, many scientists assumed that all LNPs followed more or less the same blueprint, [...]
How nanomedicine and AI are teaming up to tackle neurodegenerative diseases
When I first realized the scale of the challenge posed by neurodegenerative diseases, such as Alzheimer's, Parkinson's disease and amyotrophic lateral sclerosis (ALS), I felt simultaneously humbled and motivated. These disorders are not caused [...]
Self-Organizing Light Could Transform Computing and Communications
USC engineers have demonstrated a new kind of optical device that lets light organize its own route using the principles of thermodynamics. Instead of relying on switches or digital control, the light finds its own [...]
Groundbreaking New Way of Measuring Blood Pressure Could Save Thousands of Lives
A new method that improves the accuracy of interpreting blood pressure measurements taken at the ankle could be vital for individuals who are unable to have their blood pressure measured on the arm. A newly developed [...]
Scientist tackles key roadblock for AI in drug discovery
The drug development pipeline is a costly and lengthy process. Identifying high-quality "hit" compounds—those with high potency, selectivity, and favorable metabolic properties—at the earliest stages is important for reducing cost and accelerating the path [...]
Nanoplastics with environmental coatings can sneak past the skin’s defenses
Plastic is ubiquitous in the modern world, and it's notorious for taking a long time to completely break down in the environment - if it ever does. But even without breaking down completely, plastic [...]
Chernobyl scientists discover black fungus feeding on deadly radiation
It looks pretty sinister, but it might actually be incredibly helpful When reactor number four in Chernobyl exploded, it triggered the worst nuclear disaster in history, one which the surrounding area still has not [...]
Long COVID Is Taking A Silent Toll On Mental Health, Here’s What Experts Say
Months after recovering from COVID-19, many people continue to feel unwell. They speak of exhaustion that doesn’t fade, difficulty breathing, or an unsettling mental haze. What’s becoming increasingly clear is that recovery from the [...]
Study Delivers Cancer Drugs Directly to the Tumor Nucleus
A new peptide-based nanotube treatment sneaks chemo into drug-resistant cancer cells, providing a unique workaround to one of oncology’s toughest hurdles. CiQUS researchers have developed a novel molecular strategy that allows a chemotherapy drug to [...]
