An image obtained from the U.S. National Institute of Allergy and Infectious Diseases in Bethesda, Maryland, shows a colorized transmission electron micrograph of monkeypox particles (green) found in an infected cell (pink and purple), grown in the laboratory. Photo: © AFP, handout
 

Cases of mpox, formerly known as monkeypox, have been detected in Sweden and Pakistan, just days after the World Health Organization declared a global health emergency in response to the resurgence of cases in Africa. The current outbreak is centered on the Democratic Republic of Congo, where the disease has killed more than 500 people since the beginning of the year. Here is what we know about the new, more infectious mpox strain so far.

Scientists are concerned that a new mpox strain, formerly known as monkeypox, might be more easily transmitted among people. Monkeypox has been renamed mpox by the World Health Organization (WHO) over concerns that the original name could be construed as discriminatory and racist. 

Pakistan said Friday it had confirmed a case of mpox, a day after Sweden recorded the first infection outside of Africa involving the new strain.

The mpox surge in Africa—which has also affected Burundi, Kenya, Rwanda and Uganda—prompted the World Health Organization on Wednesday to declare a public health emergency of international concern, the highest alarm it can sound.

The health minister of the worst-hit country, the Democratic Republic of Congo (DR Congo), said Thursday that it had “recorded 15,664 potential cases and 548 deaths since the beginning of the year”. WHO said the number of recorded mpox cases in Africa through July this year exceeds figures for all of 2023.

A new form of the virus has triggered global concern because it seems to spread more easily though routine close contact.

The European Centre for Disease Prevention and Control (CDC) raised its risk alert level for mpox on Friday, and asked countries to maintain high levels of awareness among travellers visiting from affected areas.

The agency said it now sees a “moderate” risk of mpox, compared to “low” earlier, for the broader population and travellers. It added that the likelihood of sustained transmission in Europe remained very low, provided the imported cases are diagnosed quickly and control measures implemented.

 

More infectious variant
The current outbreak in the DR Congo began with the spread of an endemic strain, known as clade I. But a new variant, clade Ib, appears to spread more easily through routine close contact, including sexual contact.

Sweden’s Public Health Agency told AFP on Thursday that it had registered a case of the clade 1b, the first such infection outside the African continent, according to the agency.

The patient was infected during a visit to “the part of Africa where there is a major outbreak of mpox clade 1”, epidemiologist Magnus Gisslen said in a statement from the agency.

The mpox strain that caused the case in Pakistan was not immediately known on Friday, the ministry of health said in a statement.

China announced Friday it will begin screening people and goods entering the country for mpox over the next six months.

“It’s clear that a coordinated international response is essential to stop these outbreaks and save lives," said WHO Director-General Tedros Adhanom Ghebreyesus on Wednesday. “This is something that should concern us all.”

During the global outbreak of mpox in 2022, gay and bisexual men made up the vast majority of cases and the virus was mostly spread through close contact, including sex.

Although some similar patterns have been seen in Africa, children under 15 now account for more than 70% of the mpox cases and 85% of deaths in Congo.

This viral disease is characterised by fever, cough, headaches and rashes.

The mpox virus was first isolated in 1958 from a colony of monkeys kept for research in Copenhagen, Denmark. These monkeys showed skin lesions reminiscent of human smallpox – hence the name “monkeypox”.

 

Means of transmission
Like avian flu and coronavirus, mpox is a disease that can be transmitted from an infected animal to a human. But it is also spread between humans, notably through skin-to-skin contact with an infected person, through sex or talking or breathing close to an ill person.

The two main variants of mpox are clade 1, which is often more serious, and clade 2.

The clade 1 virus – which has been endemic in the DR Congo for decades – is spreading.

The new strain that is causing most concern, clade 1b, discovered in September 2023 in the DR Congo, is more deadly and more transmissible than the others.

Mpox can also be transmitted indirectly via contaminated materials (such as bedding), according to the Institut Pasteur in Paris

The previous mpox public health emergency, declared in 2022, was caused by the relatively mild clade 2.

In 2022, the monkeypox virus spread to around a hundred countries. The epidemic caused the deaths of 140 people out of about 90,000 cases worldwide. WHO declared it a “public health emergency of international concern” in July 2022.

Ten months later, WHO put an end to the alert after the epidemiological situation had improved significantly.

 

An epidemic more contagious than in 2022
The current outbreak has raised new concerns. According to the public health agency Africa CDC, in the 16 African countries where it has been detected, mpox cases increased by 160% in 2024 compared to 2023.

Mpox cases have been recorded in all provinces of the DR Congo, the Congolese health minister said on Thursday.

Epidemiologists have also warned that the more a virus is transmitted between humans, the greater the risk of it mutating.

“What’s happening in Africa is just the tip of the iceberg,”, said Professor Dimie Ogoina, chairman of the WHO Emergency Committee, on Wednesday.

“The current upsurge of mpox in parts of Africa, along with the spread of a new sexually transmissible strain of the monkeypox virus, is an emergency, not only for Africa, but for the entire globe,” Ogoina said.  “Mpox, originating in Africa, was neglected there, and later caused a global outbreak in 2022. It is time to act decisively to prevent history from repeating itself.”

“There are no African, Asian or continent-specific diseases,” says virologist Christian Bréchot, president of the Global Virus Network, interviewed by TV5 Monde.

 

A single health, that of the world
Bréchot’s remarks echo one of WHO’s public information campaigns: as epidemics ignore borders, there is only “one health”, that of the world.

With the memory of Covid-19 still fresh in people’s minds, WHO has just reacted “rapidly” to the resurgence of mpox, Bréchot says: “The mobilisation makes me think – personally – that there’s no reason to panic.”

On August 7, WHO director Tedros launched an emergency authorisation procedure for mpox vaccines so that they can be used in countries that have not yet approved the two products currently on the market.

Danish drugmaker Bavarian Nordic said it was ready to produce up to 10 million doses of its mpox vaccine by 2025.

The US Department of Health said Wednesday it would be donating 50,000 doses of an mpox vaccine to the DR Congo, adding that inoculation would “be a critical element of the response to this outbreak”.

 

This article has been translated from the original in French.