A new mpox outbreak in Guinea-Bissau — the nation’s first recorded outbreak — has pushed the disease once known as monkeypox back into global health headlines. But why is mpox drawing renewed concern, and what is different this time?
Since 2022, nearly 190,000 laboratory-confirmed mpox cases have been documented across 145 countries. Before that global surge, mpox outbreaks were usually limited in size and largely confined to parts of Africa where the virus had long been considered endemic.
What is mpox?
Mpox is a contagious viral illness that often begins with symptoms resembling the flu, such as fever, chills and muscle aches. A recognizable rash typically follows, starting as raised bumps that develop into fluid-filled blisters before eventually crusting over into scabs.
The disease was previously called monkeypox because the virus was first identified in captive monkeys in 1958. However, during the international outbreak in 2022, health officials warned that the name was being linked to racist and stigmatizing language both online and offline. In response, the World Health Organization recommended the shorter name mpox.
Mpox remains endemic in several regions of Africa, where outbreaks have traditionally been traced to people handling or eating meat from infected wild animals. In recent years, however, the virus has moved beyond its familiar boundaries and established longer chains of person-to-person transmission. Earlier this month, the Atlanta-based Centers for Disease Control and Prevention said mpox appears to be on track to become endemic in the United States.
Why is it spreading to new countries?
Scientists generally divide mpox into two major groups, or “clades”. Clade I was formerly known as the “Congo Basin clade”, while clade II was once referred to as the “West African clade”.
Clade II was behind the large international mpox outbreak in 2022, after the virus appeared to acquire changes that made human-to-human spread more effective. Transmission occurs through close contact and, during that outbreak, was driven largely by sexual contact, with men who have sex with men facing the highest risk.
In June 2024, researchers warned of a newly emerging clade I variant in the Democratic Republic of the Congo that also seemed better able to spread between people. The situation expanded into another significant cross-border outbreak, prompting the World Health Organization to declare a public health emergency of international concern on 14 August 2024.
“Emergence of mpox in more countries in west Africa is to be expected,” said Prof Michael Marks, of the London School of Hygiene & Tropical Medicine and University College London hospital. “Mpox outbreaks have now been declared in a number of countries in the region, including Guinea and Sierra Leone within the last 12 months.
“Mpox spreads by close physical contact. This makes it suitable to spread in a variety of different contexts, such as in close sexual networks, as was seen during the 2022 global pandemic, or areas where many people are living closely together such as settings with refugees and internally displaced people, as was seen in the DRC outbreak over the last few years,” Marks said.
What happened to those two big outbreaks?
The 2022 outbreak was declared a public health emergency in July that year. After contact-tracing and mass vaccination programmes, the status was lifted in May 2023. There had been about 90,000 infections.
The 2024 outbreak had its international public health emergency status lifted in September 2025, not because the disease had disappeared but because numbers of cases and deaths were declining and officials felt the situation had become better controlled.
If genetic testing reveales a new variant, or surveillance suggested an outbreak was spreading particularly fast, making people particularly sick or proving more deadly, global health authorities would be likely to step in again.
How worrying is the new outbreak?
Cases had not been reported in Guinea Bissau before this outbreak. Unicef said it was concerned that of 46 suspected cases, 23 were children aged under 15 and most of those were aged under four.
“The concern about children is that they are at the highest risk of severe disease and death from mpox,” said Dr Aula Abbara, a senior lecturer at Imperial College London and adviser to Médecins Sans Frontières UK. “Young children can become much sicker than healthy adults.”
However, she cautioned that the apparent over-representation of children in the outbreak data should be interpreted carefully. She said: “There may also be some bias in the data. Families are often more likely to seek healthcare for a sick child than for an adult, particularly in a resource-constrained setting with a fragile health system, such as Guinea-Bissau.”
Marks added: “Children have close physical contact with their parents and with each other, and in settings such as Guinea-Bissau are often living in cramped conditions, which make close physical contact and transmission more likely.”
Confirmed cases do not appear linked to each other, which suggests the virus is circulating more widely in the community and there are unidentified cases.
Are there vaccines and treatments?
The WHO recommends two vaccines, which can be given to people at high risk or offered to people who have been in contact with a known case to prevent further spread. The question is where they are available.
Marks said: “The major challenge remains that supplies of vaccines are best in high-income countries but worst in low-income settings, where the need and conditions for mpox transmission are highest.”
A new global stockpile is due to be launched within weeks, which should mean vaccines can be deployed more rapidly to quell outbreaks. Officials also hope it will allow manufacturers to plan ahead and produce more of the jabs by providing a clear, concrete demand.
An antiviral called tecovirimat did not appear any better than a placebo when tested on patients with mpox clade I in the DRC, although the question of whether it might help some immunocompromised patients – such as those living with HIV – remains open. That trial did show, however, that giving patients good, supportive care dramatically improved their chances of survival.
While vaccines remained an important tool for outbreak control, basic supportive care could be lifesaving, Abbara said. She added that strengthening surveillance, testing, contact tracing and broader public health measures would be critical to understanding and containing the outbreak.
“Vaccines are important, but outbreaks are not controlled by vaccines alone,” she said. “Early detection, contact tracing, supportive care and strong public health surveillance remain absolutely essential.”
