New mutant mpox strain discovered in the DRC

A new variant of mpox that may be better adapted to spread between people has been identified in the Democratic Republic of Congo.

The new strain is a mutation of Clade 1a mpox – an older variant that has been known to cause more severe disease than Clade 2, which caused a global outbreak in 2022, or Clade 1b, which has been spreading rapidly in Africa since 2023.

Dr Ngashi Ngongo, who heads the mpox incident management team at the Africa Centres for Disease Control and Prevention (Africa CDC), said the new strain raises significant public health concerns.

This is because it carries a mutation known as APOBEC3, which indicates that it may be more transmissible, he explained. The same mutation had already been seen in Clade 1b mpox, which has spread beyond the DRC to several neighbouring countries as well as Europe and Asia.

“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,” Dr Ngongo told a briefing.

Clade 1a had previously been linked to spillovers from animals, with some limited human-to-human transmission in endemic areas in central Africa. 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.

However, Dr Lorenzo Subissi, a virologist with the WHO Health Emergencies Programme, cautioned that so far such high fatality rates had not been observed.

“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,” he told The Telegraph. “Mortality will largely depend on underlying conditions of the affected population such as malnutrition.”

The discovery of the new mutant strain came as the World Health Organization extended its declaration of a public health emergency of international concern (PHEIC) over the mpox epidemic.

The unanimous decision from the WHO emergency committee was “based on the continuing rise in numbers and geographic spread, the violence in the eastern DRC, which hampers the response, as well as a lack of funding to implement the response plan,” the WHO said in a statement.

The outbreaks in Africa mainly involve Clade 1a and 1b strains of the virus, with limited transmission of clade 2.

Dr Ngongo said several countries in Africa are continuing to report rising mpox cases, while spiralling armed conflict in the DRC is increasing the risk of spread.

Fourteen out of 22 African countries affected by the epidemic are still in the active outbreak stage, he said. Among them is South Africa, which reported three new cases after going more than 90 days without reporting any.

In Uganda, surging mpox cases – the country reported 278 last week – have begun to overwhelm medical facilities, prompting the country’s ministry of health to begin at-home treatment of patients with less severe disease.

Dr Ngongo said one treatment facility in the central Ugandan city of Entebbe was currently dealing with over 100 patients despite only having 80 beds.

In the DRC, conflict is fuelling the outbreak and complicating efforts to monitor it.

More than 500 mpox patients have been forced to flee health facilities in Goma and Bukavu, two cities in the east of the country that were recently plunged into chaos when they were seized by the Rwanda-backed M23 rebels, according to local media reports.

“We were looted. We lost equipment. It was a disaster,” said Dr Samuel Muhindo, who runs a clinic in Goma.

“Now we are afraid of an outbreak of the epidemic in the areas where the displaced people returned to,” he told the BBC.

The spread of the fighting – and the freeze on USAID money that had been used to transport tests to laboratories – mean that only 35 per cent of suspected mpox cases are now being tested in the DRC.

While, overall, cases in Africa have declined in recent weeks, Dr Ngongo said this was probably the result of reporting delays and the decline in testing coverage in the DRC.

Against this backdrop of significant uncertainty around the outbreak, 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.

A new, two-pronged strategy is intended to target both high-risk areas and the contacts of confirmed cases, according to the Africa CDC. Previous vaccination campaigns have targeted frontline health workers.

Protect yourself and your family by learning more about Global Health Security