A NEW mutant strain of mpox discovered in the Democratic Republic of Congo could be better at spreading between people, health officials warn.
This new mutation of the Clade 1a mpox variant “has got high potential for higher transmissibility” and raises significant health concerns, according to the Africa Centres for Disease Control and Prevention (Africa CDC).
A mutant strain of Clade 1a mpox spotted in the Democratic Republic of Congo may be more transmissible, health officials warn[/caption]
Lack of funding and conflict in the DRC have hampered efforts to contain the outbreak[/caption]
It comes after the World Health Organisation said it still regarded the mpox outbreak as a public health emergency of international concern[/caption]
Dr Ngashi Ngongo – who heads Africa CDC’s mpox incident management team – said the variant has a mutation known as APOBEC3, which means it could spread more easily.
The same mutation had already been seen in the Clade 1b mpox variant, which has spread beyond the Democratic Republic of Congo (DRC) to several neighbouring countries in Central and Eastern Africa, as well as the UK, Europe and Asia.
There are two Clades of the virus: Clade 1 (with subclades 1a and 1b) and clade 2, which caused global mpox outbreak in 2022–2023.
Clade 1a is thought to cause more severe disease than both Clade 1b and Clade 2.
According to the World Health Organisation (WHO), most Clade 1a infections have been linked to spillovers from animals, with limited human-to-human transmission in close-contact settings like households observed.
It has a fatality rate ranging from 1.4 per cent to over 10 per cent, compared with between 0.1 per cent and 3.6 per cent for Clade 2.
In a briefing last week, Dr Ngongo warned: “Very important information from the DRC – we have seen a new variant of Clade 1a with APOBEC3 that has been detected, and unlike the old 1a variant, this one has got high potential for higher transmissibility.”
But Dr Lorenzo Subissi, a virologist with the WHO Health Emergencies Programme, told the Telegraph that higher fatality rates haven’t been observed so far.
He said: “While this variant may spread outside of DRC, the mortality rate seen in Kinshasa, where the new Clade 1a variant co-circulates with Clade 1b, remains less than one per cent, so much lower than what was historically thought to be clade Ia mortality.
“Mortality will largely depend on underlying conditions of the affected population such as malnutrition.”
The discovery came after the WHO announced that it still regarded the mpox outbreak as a public health emergency of international concern – the agency’s highest form of alert.
The WHO, which first declared the emergency in August last year, said its decision was based on continuously rising numbers of mpox cases and the geographic spread of the outbreak.
Lack of funding and violence in eastern DRC were hampering efforts to contain cases, WHO officials said.
Professor Salim Abdool Karim, chair of Africa CDC’s Emergency Consultative Group said: “The outbreak remains uncontrolled, resources are insufficient, surveillance systems are weak, and health systems in many affected countries are struggling to contain the spread.”
Dr Ngashi Ngongo shared the news about the new mutant strain in a press briefing[/caption]
Outbreaks in Africa have mainly been caused by Clade 1a and 1b strains of the virus, though some Clade 2 cases have also been spotted.
The number of reported mpox cases has surged in recent months, with the weekly average tripling from 909 in August 2024 to 3,264 in February 2025, despite response efforts.
Dr Ngongo said termination of USAID funding and violence in eastern DRC has meant that 35 per cent of mpox cases are currently being tested in DRC.
He added that fourteen out of 22 African countries affected by mpox the epidemic are still in the active outbreak stage.
Mpox and the different Clades explained
MPOX is a viral infectious disease.
It is a rare zoonosis, which means that it is transmitted to humans from an animal.
The disease primarily occurs in remote parts of Central and West Africa, near tropical rainforests.
Mpox causes symptoms between five and 21 days after exposure.
The symptoms of monkeypox start similar to the flu. But then a rash breaks out, starting on the face.
Initial symptoms include:
- Fever
- Headache
- Muscle aches
- Backache
- Swollen lymph nodes
- Chills
- Exhaustion
An itchy and sometimes painful rash slowly appears one to three days into illness, starting with the face, palms of the hands and soles of the feet.
What starts as a seemingly harmless red rash – which looks like chickenpox – evolves into angry blisters that can last several days.
The inside of the mouth, genitals and lining of the eyes can also be affected by the nasty rash.
If the rash spreads to the eyes it can cause blindness.
While some patients may have only a few lesions, others will have thousands, the WHO says.
Symptoms generally last from 14 to 21 days, with severe cases relating to age, the extent of virus exposure, the patient’s health and the severity of complications.
What are the different mpox Clades?
There are two distinct mpox Clades:
- Clade 1 (with subclades 1a and 1b)
- Clade 2 (with subclades 2a and 2b)
Clade 2 was responsible for the global mpox outbreak in 2022-2023.
For example, Uganda has seen increases in cases for three weeks in a row, which are overwhelming healthcare facilities – 278 new cases reported in the past week alone.
Meanwhile, South Africa reported three mpox cases after being free of the disease for over 90 days.
But the DRC finally began its first large-scale mpox vaccination programme last week.
Over 24,800 people received jabs for mpox in the space of four days, Dr Ngongo said.
At the same time, the DRC is also grappling with an outbreak of a mystery disease, which has killed at least 60 people.
The outbreak has infected over 1,000 people across five villages in the Equateur province.
While hundreds of cases have tested positive for malaria, patients are also presenting unusual symptoms like stiff necks, bleeding noses, vomiting, and diarrhoea.
WHO officials said they were looking into poisoning as a possible cause of the outbreaks – but noted it was too early to draw any conclusions.
Dr Michael Ryan, WHO’s emergencies chief, pointed to a “a very strong level of suspicion … related to the poisoning of a water source”.
“Clearly, at the centre of this, we have some kind of poisoning event,” Dr Ryan said, adding that the investigation could also explore other toxic sources, such as meningitis or chemical exposure.
It “appears very much more like a toxic type event, either from a biologic perspective like meningitis or from chemical exposure,” Dr Ryan said during a scheduled online news conference focused on flu prevention.
The expert did not specify if a contamination could be accidental, negligent, or intentional, nor did he name the village.
“We will not stop investigating until we are sure that the true cause or the absolute cause of what is occurring here is fully investigated,” Dr Ryan added.
