A health worker attends to a girl suffering from mpox, at a treatment centre in Munigi, eastern Congo, Friday, Aug. 16, 2024.
| Photo Credit: AP

A total of 18,737 suspected or confirmed cases of mpox were reported in Africa since the beginning of the year, including 1,200 cases in one week alone, the African Union health agency said on Saturday.

The figure accounts for three strains of the virus, of which one is the new more deadly, and more transmissible Clade 1b which prompted the World Health Organization (WHO) on Wednesday (August 14, 2024) to declare an international health emergency — the agency’s highest alert.

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To date, 3,101 confirmed and 15,636 suspected cases have been reported from 12 African Union member states, resulting in 541 deaths — a fatality rate of 2.89 percent, the Africa Centres for Disease Control and Prevention (CDC) said in a statement.

The hardest hit country, the Democratic Republic of Congo (DRC) where the new Clade 1b strain was first detected in September 2023, has reported 1,005 cases (222 confirmed, 783 suspected) and 24 deaths in one week.

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All 26 provinces in the DRC, home to some 100 million people, have reported cases.

Neighbouring Burundi reported 173 cases — 39 confirmed and 134 suspected — which marks a rise of 75% in one week.

More cases have been reported since the beginning of the year than all of 2023, which saw a total of 14,383 cases, according to the Africa CDC.

The first cases of the mpox outside of Africa were recorded this week, in Sweden and Pakistan.

The WHO will soon publish its first recommendations by its emergency committee and, along with NGOs, has also called for the ramping up of vaccine production.

Mpox is a viral disease that can spread from animals to humans, but also human-to-human through sexual or close physical contact. Symptoms include fever, muscular aches and large boil-like skin lesions

The Clade 1b causes skin eruptions all over the body, whereas previous variants caused localised lesions around the mouth, face or genitals.

The disease, formerly known as monkeypox, was first detected in humans in the DRC in 1970. The deadlier Clade 1 has been endemic in the Congo Basin in central Africa for decades.

Two years after a global outbreak, fears are rife that a new strain of mpox — previously known as monkeypox — identified in DR Congo and now also in several neighbouring countries could further spread.

Deadlier and more transmissible than previous forms, the mpox strain surging in the Democratic Republic of Congo (DRC) since September, known as the Clade Ib subclade, is spread person-to-person.

The World Health Organization (WHO) said on Sunday it was considering convening an expert committee to advise on whether to declare an international emergency, as it did during the global mpox outbreak in 2022.

The Clade Ib strain causes skin rashes across the whole body, unlike other strains where lesions and rashes are usually limited to the mouth, face and genitals.

The African Union health agency, Africa CDC, registered 14,479 confirmed and suspected cases of the strain and 455 deaths in DRC as of August 3, representing a mortality rate of around three percent.

But researchers in the vast Central African nation say the mortality rate from the strain can be as much as 10 percent among children.

The Congolese government acknowledged last month an “exponential increase” in cases.

“The disease has been seen in the displacement camps around Goma in North Kivu where the extreme population density makes the situation very critical,” Louis Albert Massing, medical coordinator for Doctors Without Borders in DRC said.

“The risks of explosion are real given the enormous population movements” in the conflict-ridden region, which borders several countries, he added.

Already, the Clade Ib strain has jumped national borders — in the last two weeks, cases have been reported in Uganda, Burundi, Rwanda and Kenya, Rosamund Lewis, the WHO’s technical lead for mpox, told AFP.

‘Raging’

Authorities in the four countries have confirmed mpox cases — Burundi in particular has reported 127 cases — without specifying the strain.

The eight-member East African Community (EAC) has urged governments to educate their citizens on how to protect themselves and prevent the spread of the disease.

Lewis, from the WHO, said it was the first time that the four countries lying to the east of DRC had reported mpox cases.

“Rwanda, Burundi, Uganda are countries that don’t have this disease in an endemic way… that means it’s an extension of the outbreak which is raging in the DRC and in Central Africa generally,” she said.

Africa CDC has also reported 35 suspected and confirmed cases, including two deaths, in Cameroon, 146 cases, including one death, in Congo Brazzaville, 227 cases in the Central African Republic, 24 in Nigeria, five in Liberia and four cases in Ghana.

In West Africa, Ivory Coast recently reported six confirmed non-fatal cases, five of which were in the economic capital Abidjan, without specifying the strain.

Detection capacity

Mpox was first discovered in humans in 1970 in the DRC, then called Zaire. It has since been mainly limited to certain West and Central African nations. Humans mainly catch it from infected animals, such as when eating bushmeat.

In May 2022, mpox infections surged worldwide, mostly affecting gay and bisexual men. That spike was driven by a new subtype, dubbed Clade II, which took over from Clade I. Around 140 people died out of about 90,000 cases across 111 countries.

The outbreak is “still raging”, Lewis said, including in South Africa, which has seen 24 cases, three of which were fatal, but she added it was “controlled” and spreading less.

Mpox remains a global health threat, WHO chief Tedros Adhanom Ghebreyesus warned in early July.

Countries are now able to detect cases, Lewis said, pointing to a system of surveillance, laboratories and communication with affected areas. It is hard to know if there has been “a substantial rise” in cases, or whether “it’s just a matter of increased awareness”, said Maria Van Kerkhove, the WHO’s epidemic and pandemic preparedness and prevention director, who confirmed concern over the Clade Ib strain.

“There are some vaccines that are licensed that can be used for mpox,” she said.

Negotiations between the WHO and affected countries are under way to authorise the use of one, Lewis said.

Poxviruses have long been a cause of fear as well as curiosity for humankind. One particularly infamous poxvirus, smallpox, alone may have killed more than 500 million people in the last century.

Smallpox didn’t discriminate between rich, poor, young, old, and killed a third of the individuals whom it infected. The turning point came with evidence of the efficacy of the smallpox vaccine. Thus followed a concerted effort worldwide to administer the vaccine and eventually eradicate the dread disease. This feat has stood as a testament to the power of sustained global public health initiatives.

Mpox’s 15 minutes

Another poxvirus, mpox, was recently in the headlines after a rapidly expanding global outbreak in 2022-2023. The virus was previously called ‘monkeypox’ after a spillover event in a research facility involving monkeys in 1958; the name is considered both wrong and inappropriate today: since then, researchers have identified mpox in many sporadic outbreaks among humans. They have also found multiple mpox lineages have been circulating in humans, adapting by accumulating mutations modulated largely by the APOBEC proteins.

But it wasn’t until 2022 that the disease became widely known, thanks to outbreaks in more than 118 countries and the World Health Organisation (WHO) quickly declaring it a public health emergency. To date, this outbreak has infected almost 100,000 people. Based on WHO data, infections have a mortality rate of 1-10%.

The outbreak was due to one clade (strains of the virus descended from a common ancestor) — called IIb — having developed very high human-to-human transmission through close contact and spread through the sexual route. While the rate of new infections has been dropping, mpox continues to circulate among unvaccinated individuals worldwide. This increases the chance that a more virulent and transmissible strain might emerge and become endemic somewhere.

Expanding, contracting as required

Mpox, like all poxviruses, are DNA viruses. The mpox genome has about 197 kilobases (kb). The core genes are those closely conserved (i.e. preserved during evolution) by various poxviruses plus two sections about 6.4 kb long, one at each end of the genome. Researchers don’t yet know what function these sections serve but suspect they influence how well the poxviruses can infect different hosts.

The mpox genome also has a sequence of bases repeating in a pattern, which researchers believe play a role in the virus’s evolution.

The mpox family of viruses is also known to be able to evade selective evolutionary pressures. It does this by duplicating genes and/or accumulating mutations and expanding its genome significantly — or contracting its genome by deleting gene stretches or inactivating them. Such rhythmic expansions and contractions are called genomic accordions.

Find the accordion

In a study published on April 18 by Nature Communications, researchers at the Icahn School of Medicine in New York and multiple institutions in Spain extensively sequenced the genome of the mpox virus implicated in the 2022 outbreak. They used advanced genome sequencing technologies to piece together a comprehensive genome of the mpox virus from scratch.

They found that the 6.4-kb-long sections of the virus strongly influenced the virus’s human-to-human transmissibility. They also reported that variations in three genes in particular could affect the virus’s evolution. Importantly, 6.4-kb-long sections, which scientists had previously considered to be not so informative, were actually found to be the virus’s genomic accordions.

All mpox genomes can be divided into two distinct yet broad clades: I and II. Clade I is thought to have a higher mortality. Each clade has sub-clades, or lineages, defined by specific evolutionary processes. Researchers have also found evidence of significantly different mpox virulence in animal models. The new study, like others like it, further the idea that the 2022 outbreak largely involved a new lineage of the virus, clade IIb, that was even better adapted to human-to-human transmission than clades I or IIa.

The outbreak in the DRC

Between September 2023 and February 2024, health workers detected a large mpox outbreak detected in the Democratic Republic of the Congo (DRC), centred on a mining village and quickly spreading to a number of regions within the country. This outbreak was associated with a significantly larger spread as well as mortality. Researchers soon confirmed mpox clade I was responsible.

This outbreak differed from earlier ones, which were sporadic and self-contained spillover events, by spreading through human-to-human contact and affecting young adults rather than children. A preprint paper, uploaded by researchers from Belgium, Canada, the DRC, France, Ghana, Nigeria, South Africa, and the U.S., on April 14 describes the genomes of virus samples obtained from 241 individuals suspected to have been infected during the outbreak.

The genomic data suggests a distinct lineage of clade I being associated with human-to-human transmission. The researchers also found evidence — in fragments of the genome that closely resembled viruses isolated and sequenced in recent years — of the hypothesis that this lineage emerged from a very recent zoonotic spillover.

One eye on the genome

As with any viral infection, without urgent intervention, the outbreak has the potential to spread rapidly across national, and even continental, boundaries and emerge as another global outbreak.

To prevent such an outcome, genome sequences from before and during mpox outbreaks have provided well-lit glimpses of the evolutionary dynamics the virus uses to invent new ways to move between and survive in different populations of animals and people.

Thus, through rigorous genomic investigations and coordinated public health efforts, we can mitigate the threat of emerging pathogens and the world’s health security.

The authors are senior consultants at the Vishwanath Cancer Care Foundation and Adjunct Professors at Indian Institute of Technology Kanpur. All opinions expressed are personal.