Hidden mpox exposure detected in healthy Nigerian adults, revealing under-recognized transmission

University of Cambridge

FacebookXLinkedInWeChatBlueskyMessageWhatsAppEmail

The mpox virus appears to be circulating silently in parts of Nigeria, in many cases without the symptoms typically associated with the disease, according to new research led by scientists from the University of Cambridge and partners in Nigeria. The findings may have implications for controlling the spread of the disease.

In a study published today in Nature Communications, researchers show that exposure to the mpox virus can occur without recognised illness, and that residual immunity from historic smallpox vaccination continues to shape how the virus spreads in human populations.

Mpox is a zoonotic virus – that is, one that initially jumped species to spread from animals to humans. It is closely related to smallpox. For decades, smallpox vaccination provided broad protection against related viruses such as mpox. Following the eradication of smallpox, routine vaccination stopped in 1980 and a growing proportion of the population lost this protection. This shift has been accompanied by renewed mpox transmission, culminating in outbreaks seen in multiple countries between 2022 and 2024.

While most public health attention has focused on symptomatic mpox cases, little is known about how often people may be exposed to the virus without developing classical disease.

To investigate this, the research team analysed archived blood samples from 176 healthy Nigerian adults who had originally been enrolled in SARS-CoV-2 vaccine studies. These included healthcare workers sampled in 2021 and community volunteers sampled in 2023. None of the participants had received mpox or smallpox vaccines in adulthood, and none were known to have been exposed to mpox.

Using a high-resolution multiplex antibody assay, the researchers measured responses to six distinct mpox virus antigens, different structural components of the virus that the immune system recognises and responds to, allowing detection of both the strength and breadth of immune responses.

At baseline, 24 (14%) of the participants showed antibody profiles consistent with residual immunity from historic smallpox vaccination. These responses were concentrated in people born before 1980, who were more likely to have been vaccinated during childhood. Their antibody responses were broader and stronger, recognising multiple mpox antigens decades after vaccination campaigns ended.

However, the study also identified something unexpected.

Among 153 participants with follow-up samples collected approximately nine months later, five individuals - around 3% of the cohort - showed clear evidence of new immune boosting consistent with recent mpox exposure. These individuals had no recorded mpox diagnosis and did not report compatible illness, suggesting that exposure may have occurred without recognised disease.

Lead author Dr Adam Abdullahi, from the University of Cambridge and Institute of Human Virology Nigeria, said: “What we’re seeing is evidence that mpox exposure doesn’t always look like the textbook description. In some people, particularly in settings with partial population immunity, the virus may circulate quietly, leaving immune footprints that routine clinical surveillance will miss.”

The strongest antibody increases were directed against specific viral proteins, particularly B6R, A35R and M1R - antigens known to be important targets of protective immune responses. These findings suggest that certain immune markers could be especially useful for detecting recent exposure in population studies.

To place the immunological findings in an epidemiological context, the team also analysed more than 100 mpox virus genomes collected in Nigeria over several years. Genomic reconstruction showed slow epidemic growth, frequent transmission dead-ends, and limited clustering – a pattern consistent with ongoing transmission constrained by partial immunity in the population.

Rather than explosive spread, the virus appears to persist through sporadic chains of infection, many of which fail to expand further.

Senior author Professor Ravindra Gupta is The Hong Kong Jockey Club Professor of Global Health from the Cambridge Institute of Therapeutic Immunology and Infectious Disease, University of Cambridge, and Co-Director of the Hong Kong Jockey Club Global Health Institute. He said: “Our data tell a consistent story. Mpox is not spreading unchecked in Nigeria and across the region, but neither is it absent. Instead, it appears to circulate at low levels, shaped by the lingering effects of smallpox vaccination in older generations.”

Importantly, the study found no major differences in immune responses between healthcare workers and the general population, suggesting that exposure is not confined to clinical settings. This points to broader community-level transmission rather than purely occupational risk.

The findings have important implications for public health surveillance. Current mpox monitoring relies heavily on detecting symptomatic cases, yet this approach may underestimate true exposure, particularly where infections are mild or atypical.

Professor Alash’le Abimiku, Executive Director of the Institute of Human Virology Nigeria, said: “These findings show that mpox exposure can occur without obvious illness. Instead of relying solely on reported cases or symptoms, monitoring populations by testing blood samples for antibodies to reveal exposure to the virus will be important for understanding how it is spready and guiding targeted vaccination in our settings.”

“If we only look for obvious disease, we will miss part of the picture,” said Dr Abdullahi. “Monitoring blood samples gives us a way to detect exposure that doesn’t result in clinic visits, especially in regions where health systems are stretched and requires strengthening.”

The researchers stress that their findings do not suggest widespread silent epidemics but rather highlight the complexity of mpox transmission in populations with mixed immunity. The detected exposure rate reflects the study cohort and should not be interpreted as population prevalence.

The work also reinforces the long-lasting impact of smallpox vaccination. Individuals vaccinated decades ago still show broad immune recognition of mpox virus, which may help limit transmission even today.

Professor Gupta added: “This study reminds us that decisions made generations ago - such as ending smallpox vaccination - continue to shape how emerging infections behave. Understanding that legacy is crucial for designing rational vaccination and surveillance strategies now.”

The authors note that further work is needed to link antibody patterns to functional protection, to study cellular immune responses, and to assess how conditions such as HIV infection may modify mpox immunity.

The research was supported by the Cambridge-Africa program, Wellcome Trust, the Hong Kong Jockey Club Global Health Institute, and partners in Nigeria and Europe.

Reference

Abdullahi, A et al. Sero-genomic evidence 1 for occult mpox exposure in healthy Nigerian adults. Nat Comms; 20 Jan 2026; DOI: 10.1038/s41467-026-68335-1

---

Journal

Nature Communications

DOI

10.1038/s41467-026-68335-1 

Method of Research

Observational study

Subject of Research

People

Article Title

Sero-genomic evidence 1 for occult mpox exposure in healthy Nigerian adults

Article Publication Dat

20-Jan-2026

58% of patients affected by 2022 mpox outbreak report lasting physical symptoms

American College of Physicians

Below please find summaries of new articles that will be published in the next issue of Annals of Internal Medicine. The summaries are not intended to substitute for the full articles as a source of information. This information is under strict embargo and by taking it into possession, media representatives are committing to the terms of the embargo not only on their own behalf, but also on behalf of the organization they represent.   
----------------------------    

1. 58% of patients affected by 2022 mpox outbreak report lasting physical symptoms

Abstract: https://www.acpjournals.org/doi/10.7326/ANNALS-25-00036

Summary for Patients: https://www.acpjournals.org/doi/10.7326/ANNALS-25-00036-PS

URL goes live when the embargo lifts             

A cohort study of over 300 adults either diagnosed with mpox between May 2022 to January 2023 (post-MPX) and or who were at risk but never infected (no-MPX) found that more than half of those diagnosed with mpox during the 2022 outbreak still had lingering physical effects 11 to 18 months later. Most reported appearance-related changes, and some continued to experience anorectal or urinary problems. The study is published in Annals of Internal Medicine.  

 

Researchers from the Centers for Disease Control and Prevention, Columbia University Division of Infectious Diseases, and University of Texas Health Science Center Houston sought to understand the long-term psychosocial and behavioral impact between at-risk persons who had or did not have mpox during the 2022 mpox outbreak. The researchers recruited post-MPX and no-MPX participants from health centers in New York City, NY and Houston, TX to complete psychosocial and behavioral self-assessments followed by a clinical evaluation among the post-MPX group. The study found that 58% of those infected had at least one persistent symptom. Among post-MPX participants with appearance-related sequelae, the extent of sequelae was relatively low, with most having fewer than 10 scars or sites of discoloration and 2 or fewer body sites involved. Thirteen percent of post-MPX participants experienced ongoing physical function changes, and 2% had their activities of daily living affected. The findings provide context into the enduring physical and psychosocial effects that may occur because of mpox.

 

Media contacts: For an embargoed PDF, please contact Gabby Macrina at gmacrina@acponline.org. To contact corresponding author Preetam Cholli, MD, please submit a CDC Request for Comment Form.

----------------------------    

2. Bariatric surgery shows advantage over medical therapy for diabetes across all social backgrounds

Abstract: https://www.acpjournals.org/doi/10.7326/ANNALS-24-01882

URL goes live when the embargo lifts             

In a long-term analysis of people with type 2 diabetes, researchers found that bariatric surgery led to greater weight loss and better blood sugar control than medical and lifestyle treatment, regardless of whether participants lived in socially disadvantaged neighborhoods. The findings suggest social vulnerability level does not change the benefits of bariatric surgery over medical therapy in those with type 2 diabetes. The study is published in Annals of Internal Medicine.  

 

Researchers from the Joslin Diabetes Center and Harvard Medical School and colleagues analyzed data from 258 adults with type 2 diabetes who were enrolled in randomized trials comparing bariatric surgery with medical therapy to determine if social vulnerability influenced the effectiveness of bariatric surgery compared to medical and lifestyle interventions including individualized nutrition counseling and instruction on exercise and self-monitoring of glucose. They linked participants’ ZIP codes to the Area Deprivation Index to determine social vulnerability and analyzed changes in weight and hemoglobin A1c levels over 7 to 12 years. Bariatric surgery showed greater long-term effectiveness than medical and lifestyle interventions for both glycemic and weight loss outcomes across all levels of social vulnerability. However, the researchers did not find statistically significant differences in the comparative advantage of surgery over medical therapy by ADI levels.

 

Media contacts: For an embargoed PDF, please contact Gabby Macrina at gmacrina@acponline.org. To contact corresponding author Mary Elizabeth Patti, MD please email mary.elizabeth.patti@joslin.harvard.edu.

----------------------------   

Also new this issue:

GRADE Guidance: Update on Developing Good Practice Statements in Guidelines

Omar Dewidar, HBSc, MSc, et al.

Research and Reporting Methods

Abstract: https://www.acpjournals.org/doi/10.7326/ANNALS-25-00431

Editorial: https://www.acpjournals.org/doi/10.7326/ANNALS-25-04964

 

---

Journal

Annals of Internal Medicine

DOI

10.7326/ANNALS-25-00036 

Method of Research

News article

Subject of Research

People

Article Title

Long-Term Mpox Sequelae 11 to 18 Months After Acute Illness: A Cohort Study in Two U.S. Cities

Article Publication Date

20-Jan-2026

Top disease experts become dog-walkers and yoga instructors after Trump's CDC purge

Daniel Hampton
January 19, 2026 

RAW STORY


The main campus of the Center for Disease Control and Prevention (CDC) in Atlanta, Georgia, U.S., August 27, 2025. REUTERS/Alyssa Pointer

Elite disease experts are trading microscopes for yoga mats and dog leashes after sweeping purges left Atlanta's public health sector in freefall.

Thousands of seasoned epidemiologists and infectious disease specialists have fled the agency following the Trump administration's dramatic staff reductions to the Centers for Disease Control and Prevention, leaving some of the world's top medical minds scrambling for work, The New York Times reported Monday night.

Dr. Jennifer McQuiston, 54, a decorated veteran with a veterinary degree who spent years battling emerging zoonotic diseases, ditched her corner office for early retirement and now spends her days at an animal shelter and riding horses.

"It was my calling," she explained. "I don't mourn the loss at this moment, because I don't believe the agency is the same agency I worked in."

She took early retirement, fearing the agency had departed from its commitment to science.

The exodus has decimated Atlanta's once-proud public health ecosystem. The CDC workforce plummeted from roughly 13,500 employees at the start of 2025 to fewer than 10,000 by October, according to former agency leaders who resigned in protest. Former epidemiologist Dr. Elizabeth Soda, who developed health screening protocols for immigrants and refugees, fled to Italy with her family after a gunman fired dozens of rounds through CDC headquarters in August.

"We go through massive, real guilt moments," Soda said. "That’s one of the hardest things being here, to be honest, is knowing what we’ve left behind, who we’ve left behind — family, friends, our country."

Health Secretary Robert F. Kennedy Jr.'s controversial vision has left the nation vulnerable to emerging threats like mpox and Zika, critics warn. Public trust in the CDC has cratered to 62 percent, down from 88 percent in 2020.

 

Vaccine against foot-and-mouth disease could deliver $1.3 billion a year in global livestock benefits

The new foot-and-mouth disease vaccine developed by researchers at Diamond Light Source is projected to deliver over $1.3 billion in annual benefits and transform global livestock resilience

Diamond Light Source

FacebookXLinkedInWeChatBlueskyMessageWhatsAppEmail

The new foot-and-mouth disease vaccine developed by researchers at Diamond Light Source is projected to deliver over $1.3 billion in annual benefits and transform global livestock resilience. 

An impact report prepared by CSIL shows that Diamond played a crucial role in developing the next generation foot-and-mouth disease vaccine that could significantly strengthen global food security, reduce economic losses in livestock systems, and deliver billions in long-term benefits for farmers worldwide. 

Diamond Light Source identified as a decisive factor 

The report, written by lead author Jessica Catalano, consistently highlighted the pivotal role of Diamond in accelerating vaccine development, with CSIL noting several features that distinguish the facility on the international stage. 

These include a unique combination of advanced X-ray crystallography and electron microscopy capabilities, the ability to carry out in-situ data collection directly from sealed crystallisation plates, and the expertise of a highly skilled scientific and technical workforce. In addition, Diamond’s proactive and collaborative approach to working alongside both academic and industrial partners was seen as a key strength. 

Projected global economic benefits 

CSIL’s economic modelling indicates that introducing a virus-like particle-based vaccine with just 20% market penetration across countries where foot-and-mouth disease is endemic could deliver substantial global economic benefits. The analysis suggests net benefits of around $1.3 billion per year, a benefit–cost ratio of 1.59, and approximately $11 billion in avoided losses over a ten-year period. These estimates are regarded as conservative, largely because foot-and-mouth disease infections are widely under-reported worldwide, meaning the true economic impact of a new vaccine could be significantly greater. 

A platform for future vaccine innovation 

The report concludes that virus-like particle technology, supported by major scientific infrastructures like Diamond, could transform vaccine strategies not only for FMD, but potentially for other livestock and zoonotic diseases. 

Similar research has already been undertaken at Diamond Light Source utilising virus-like particles to develop a polio vaccine. The research on VLP vaccines has also been successfully used on other diseases like hepatitis B and human papillomavirus (HPV).  

The novel virus-like particle 

The CSIL report evaluated the novel virus-like particle vaccine developed by Diamond Light Source, the Pirbright Institute, MSD Animal Health, the University of Oxford and the University of Reading. Unlike traditional inactivated vaccines, virus-like particle vaccines contain no genetic material and can be manufactured without handling a live virus, making them safer, simpler and more scalable. 

Virus-like particle vaccines offer several significant advantages, including greater heat stability, which makes them better suited to regions with unreliable cold-chain infrastructure. They enable safer and more efficient manufacturing processes, as they do not require high-biosafety containment facilities. In addition, their simpler storage and transport requirements reduce logistical barriers, while their potential for faster adaptation to new viral variants makes them particularly valuable for rapid outbreak response. 

The vaccine is currently undergoing regulatory approvals with MSD Animal Health and production is expected in the coming years. 

Foot-and-mouth disease and its devastating effects 

Foot-and-mouth disease is one of the world’s most infectious animal viruses. According to the World Organisation for Animal Health (WOAH), foot-and-mouth disease affects 77% of the global livestock population, primarily in Africa, the Middle East, Asia and some countries in South America. The disease is not usually fatal for adult animals, but the symptoms can cause serious consequences. 

When outbreaks occur, milk and meat yields can fall sharply, and animals may no longer be able to provide reliable labour. Countries also often face tough restrictions on international trade. These impacts are felt most acutely by smallholder farmers in low- and middle-income countries, where the disease is widespread and livelihoods are closely tied to livestock. 

Efforts to control the disease are further challenged by the virus’s complexity. There are at least seven major serotypes, and immunity to one does not protect against the others. Current vaccines also have important drawbacks: they rely on the production of live virus in high-biosafety facilities, are sensitive to heat, and do not allow differentiation between vaccinated and infected animals. 

Quotes:  

Diamond chief executive Gianluigi Botton: This research has delivered an outstanding scientific breakthrough. It highlights the vital role Diamond plays in enabling solutions to issues that affect countries worldwide. With this vaccine now moving closer to production, we have a real opportunity to make a substantial impact on global animal health and support more resilient livestock systems. 

Professor Sir David Stuart, lead researcher and Professor of Structural Biology at the University of Oxford: “This impact report highlights how investment in fundamental structural biology translated into real-world outcomes. Our work on the foot-and-mouth disease vaccine demonstrates how understanding viral structure at the molecular level can directly inform vaccine design and strengthen global preparedness against infectious disease.” 

About Diamond Light Source 

Diamond Light Source is the UK’s national synchrotron serving scientists and researchers from around the world. It is a not-for-profit joint venture funded by UK Research & Innovation (UKRI) and Wellcome. Diamond provides academic and industry researchers access to facilities that enable world-changing science. The machine generates extremely bright light that is directed into laboratories known as beamlines. Scientists use the light to find solutions to humanity’s most critical challenges, from health, food security and biotechnology to energy, climate change and advanced materials. Diamond is in the process of upgrading to a fourth-generation synchrotron, generating a brighter and more coherent light. This will provide enhanced imaging and analysis capabilities, helping the UK to remain at the forefront of scientific discovery. 

About CSIL 

CSIL is an independent, employee-owned research institute established in Milan in 1980, specialising in applied economic research, public policy evaluation and socio-economic impact analysis. The organisation provides evidence-based studies and analytical support to European Union institutions, international organisations and national authorities. CSIL’s expertise spans research and innovation policy, industrial development and the assessment of major public investments, with particular strength in evaluating research and technology infrastructures. The institute applies advanced quantitative and qualitative methods to assess the scientific, economic, and societal impacts, supporting decision-makers in understanding how scientific excellence generates innovation, competitiveness, and long-term benefits. CSIL also contributes to the development of impact frameworks, performance indicators and knowledge-valorisation metrics that enhance the quality and transparency of public investment decisions. 

---

DOI

10.5281/zenodo.18220308 

Method of Research

Case study

Subject of Research

Not applicable

Article Title

Diamond contribution to the development of an innovative vaccine for Foot-and-Mouth Disease: a veterinary pathology of global significance

Article Publication Date

12-Jan-2026

 

Bats identified as origin of unexplained acute respiratory illness and encephalitis in Bangladesh

Columbia University's Mailman School of Public Health

FacebookXLinkedInWeChatBlueskyMessageWhatsAppEmail

Infectious disease researchers have identified Pteropine orthoreovirus (PRV), an emerging bat-borne orthoreovirus, in archived throat swab samples and virus cultures from five patients in Bangladesh who were initially suspected to have Nipah virus infection but tested negative. This adds PRV to the list of zoonotic viruses detected in humans in Bangladesh and suggests that it should be considered in the differential diagnosis of Nipah-like illnesses. The study appears in the journal Emerging Infectious Diseases.

All five patients had recently consumed raw date-palm sap—a sweet liquid also enjoyed by bats, especially during winter months—and a known vector for Nipah infections in Bangladesh. Bats are the natural reservoir of numerous known and novel zoonotic viruses, including rabies, Nipah, Hendra, Marburg, and SARS-CoV-1.

“Our findings show that the risk of disease associated with raw date palm sap consumption extends beyond Nipah virus,” said Nischay Mishra, PhD, associate professor of epidemiology at the Center for Infection and Immunity (CII), Columbia University Mailman School of Public Health, and senior author of the study. “It also underscores the importance of broad-spectrum surveillance programs to identify and mitigate public health risks from emerging bat-borne viruses.”

Between December 2022 and March 2023, five patients were admitted with symptoms consistent with Nipah virus infection (including fever, vomiting, headache, fatigue, increased salivation, and neurological), but tested negative for Nipah virus by PCR and serology.  Researchers used high-throughput, agnostic viral capture sequencing (VCS) to analyze biological samples from the five patients and detected PRV sequences in archived throat swab specimens. PRV was also cultured from three of these samples, providing evidence of infectious virus.

Patients were enrolled under a Nipah virus surveillance program established by the Institute of Epidemiology, Disease Control and Research (IEDCR), Bangladesh; International Centre for Diarrheal Disease Research, Bangladesh (icddr,b); and U.S. Centers for Disease Control and Prevention (CDC).

Viral Capture Sequencing (VCS) is a patented technology developed in the CII at Columbia University to rapidly screen for all viral infections of vertebrates, including infections of bats. It is as sensitive as the gold-standard polymerase chain reaction (PCR) assays while enabling simultaneous testing for thousands of viruses and providing near-complete genome sequences. A correlate method, Bacterial Capture Sequencing (BCS), allows detection of pathogenic bacteria and genes for antimicrobial resistance. Both VCS and BCS are approved for clinical and research use.

All five patients experienced severe disease, although PRV infections reported elsewhere in neighboring countries have often been milder, suggesting that less severe cases in Bangladesh may be undetected.

“A new addition of zoonotic spillover causes respiratory and neurological complications following consumption of raw date palm sap next to Nipah virus infection,” says Tahmina Shirin, PhD, Director, Institute of Epidemiology, Disease Control, and Research (IEDCR), as well as the National Influenza Centre (NIC) in Bangladesh.

In a study conducted more recently that was supported by the U.S. Department of Agriculture, Mishra and colleagues identified the source of infections by identifying genetically similar Pteropine orthoreoviruses in bats captured in proximity to the five human cases near the Padma River Basin (unpublished data).

“This [research] provides critical evidence linking bat reservoirs to human infection. We are now working to understand the spillover mechanisms from bats to humans and domestic animals, as well as the broader ecology of emerging bat-borne viruses in communities along the Padma River Basin,” says Ariful Islam, bat-borne disease ecologist and epidemiologist at Charles Sturt University, Australia, and co-first author of the study.

The study’s co-first author is Sharmin Sultana, assistant professor of Virology and Senior Scientific Officer at the Institute of Epidemiology, Disease Control and Research (IEDCR) in Bangladesh. Additional authors include James Ng, Sunil Kumar Dubey, Cheng Guo, and W. Ian Lipkin of the CII; Manjur Hossain Khan at IEDCR in Bangladesh; Mohammed Ziaur Rahman and Moinuddin Satter at icddr,b in Bangladesh; Joel M. Montgomery at the CDC’s National Center for Emerging and Zoonotic Infectious Diseases; and  Lisa Hensley at the Zoonotic and Emerging Disease Research Unit, in the United States Department of Agriculture.

The research was supported with funds provided by United States Department of Agriculture agreements with Columbia University (NACA-58-3022-2-021, NACA- 58-3022-4-053).

The authors declare no conflicts

---

Journal

Emerging Infectious Diseases

Method of Research

Observational study

Subject of Research

People

Article Title

Bat Reovirus as Cause of Acute Respiratory Disease and Encephalitis in Humans, Bangladesh, 2022–2023

Article Publication Date

5-Jan-2026