The World Health Organisation said mpox cases in the region of Congo where a new and more infectious variant was first detected appear to be “plateauing”, even as the virus continues to increase in other regions of the country, as well as in Burundi and Uganda.

In a report Monday, the UN health agency said the number of mpox infections “shows a general rising trend” but that they may have plateaued in South Kivu, where the more infectious form of mpox was first identified to be spreading earlier this year among sex workers and miners in the gold mining town of Kamituga.

WHO acknowledged, however, that testing is still not widespread, making it difficult to understand how exactly the virus is spreading.

According to data from last week, Congo reported fewer than 100 laboratory-confirmed mpox cases, down from nearly 400 in July. In recent weeks, experts say that infections appear to be stabilising, offering a chance for health authorities to definitively stamp out the outbreak.

So far, about 50,000 people in Congo have been immunised against mpox; the Africa Centres for Disease Control and Prevention estimate that 3 million vaccines are needed to stop the outbreak.

WHO said the mpox outbreak in Burundi is also being driven by the newer variant, which causes less severe symptoms — meaning people who are infectious may not realise they are spreading it. In the last two weeks, Burundi has reported more than 200 new mpox cases every week, mostly in children and young adults.

In Uganda, which reported 100 new cases last week, WHO said the virus is spreading mostly through sex, with the vast majority of cases in adults.

Mpox, which was previously known as monkeypox because it was first seen in research monkeys, is spread primarily through close skin-to-skin contact with infected people or their soiled clothes or bedsheets. It often causes visible skin lesions that could make people less likely to be in close contact with others.

In August, WHO declared the rapid spread of mpox in Congo and elsewhere in Africa to be a global health emergency. To date, Africa has reported more than 46,000 suspected cases, including 1,081 deaths.

WHO also said it would convene an expert meeting next Monday to determine if mpox still constitutes an international emergency.

Last week, Britain announced the first instance of the more infectious kind of mpox spreading beyond Africa. It identified mpox in a person who had recently travelled to Africa and in three of their household contacts. All the individuals are currently being treated in two London hospitals.