Deadly MPOX strain rapidly spreading in the Democratic Republic of Congo

Urgent action is needed to stop the spread of a new, primarily heterosexually transmitted, strain of MPOX that has caused more than 1,000 cases in the Democratic Republic of Congo, say medical experts responding to the outbreak, who fear the disease could spread to neighboring countries and even further afield.

“Given the method of infection, the way it spreads and the symptoms, it is by far the most dangerous of the known strains of MPOX so far,” he said. John Claude Udahemka At the University of Rwanda.

The new variant was first identified in September in Kamitsuga, a small mining town in South Kivu province in eastern Democratic Republic of Congo. In recent weeks, it has spread to cities in the region and may already have spread to neighboring countries such as Rwanda, Burundi and Uganda, said Léandre Murfula Masirika of the South Kivu provincial health office.

Masirika said the first case was confirmed yesterday in the city of Goma, on the border with Rwanda.

Experts hope that a vaccination campaign targeting sex workers and health care workers could stop the spread of the new strain. The campaign could make use of existing stocks of smallpox vaccines that are known to protect against other smallpox strains. But it's not yet known whether the existing vaccines would work against the new strain, Udahemuka said. “We're hopeful that they will.”

So far, the vaccine used in MPOX has not reached the affected areas, and it is unclear when it will arrive.

For decades, Central Africa has experienced occasional outbreaks of mpox (previously called monkeypox), caused by lineage 1 mpox, which is prevalent in non-human animals and can infect people who handle bushmeat. Lineage 1 can be spread by close contact with infected people or contaminated items, but does not usually spread outside the household.

In September 2023, health workers in Kamitsuga confirmed a number of cases that appeared to have been transmitted through sexual contact or other close contact. The disease was different in other ways, too: symptoms were more severe and lasted longer than usual, and many of the cases were in children. “They had a terrible rash all over their bodies,” a health worker in Kamitsuga said. Trudy Lang At Oxford University.

It has been suggested that sexual transmission may be due to the lineage 2 mpox strain, which has spread to many countries around the world in 2022. In the West, people at highest risk, including gay men, have been targeted for vaccination.

But when Udahemuka and his colleagues sequenced the genome of samples taken from the Chinese hemlock moth in February, they found that the cases were caused by a variant of lineage 1, now known as lineage 1B. Unlike lineage 2, lineage IB is spread primarily through heterosexual sex and nonsexual contact.

“It's very worrying,” said Lang, who noted high rates of infection between mothers and other caregivers and their children, as well as non-sexual person-to-person transmission outside the home.

Lineage 1B has a mortality rate of about 5% in adults and 10% in children, Lang said. The virus can also cause miscarriages and stillbirths.

Lang said those figures are based on people who were treated in hospitals, and it's possible that many more people are infected but have only mild symptoms or never show any symptoms at all.

If that were the case, the actual death rate would be lower. But if people are contagious even when they have no symptoms, it would be harder to prevent the virus from spreading. “We only know the really severe cases, and we don't know how many non-severe cases are hidden,” Lang said.

The outbreak in Kamitsuga began during the rainy season, when poor road conditions meant it could take days to reach the town, Udahemuka said, which may have limited the disease's spread, but now that the dry season has arrived, it has spread to many other towns.

“The number of cases continues to grow day by day,” said Massirika, who believes it is only a matter of time before the new variant spreads.

Udahemuka said other countries should prepare for the virus' arrival, and more importantly, support local health efforts to stop it spreading, he said.