Mpox cases have soared by 160% in Africa this year, as a lack of both vaccines and treatments hamper efforts to slow the spread of the virus.

In a report released by the Africa Centers for Disease Control and Prevention on Wednesday, officials said that mpox has now been detected in 10 African countries this year, including Congo, a country that has been the center of the latest outbreak. That nation has seen more than 96% of all cases and deaths. Even more troubling, nearly 70% of Congo cases have been in children under the age of 15, who also accounted for 85% of mpox deaths.

Doctors Without Borders called the expanding mpox outbreak in the Congo “worrying.”

“There is a real risk of explosion, given the huge population movements in and out,” Dr. Louis Massing, the group’s medical director for Congo, said in a statement issued Wednesday. “We can only plead … for vaccines to arrive in the country and as quickly as possible so that we can protect the populations in the areas most affected."

So far this year, there have been an estimated 14,250 mpox cases in Africa, almost as many as were reported in all of 2023. Compared to the first seven months of 2023, cases are up 160% and deaths are up 19%, to 456.

The countries of Burundi and Rwanda both reported mpox cases for the first time this week. New outbreaks were also declared this week in Kenya and Central African Republic, with cases extending to its capital, Bangui, the Associated Press reported.

“We are very concerned about the cases of monkeypox, which is ravaging [the capital region],” Pierre Somse, the Central African Republic’s public health minister, said this week, the AP reported.

Meanwhile, Kenya’s Health Ministry said Wednesday it found mpox in a passenger traveling from Uganda to Rwanda at a border crossing in southern Kenya, the AP reported.

Earlier this year, scientists reported the emergence of a new and deadlier version of mpox in a Congolese mining town. Mpox spreads through close contact with infected people, including via sex.

Meanwhile, an analysis of patients hospitalized from October to January in eastern Congo suggested that the recent genetic mutations seen in the virus were triggered by its rapid spread in that country, the AP reported.

Earlier this week, the Coalition for Epidemic Preparedness Innovations announced it was starting a study in Congo and other African countries next month to see if giving people an mpox shot after they have been exposed to the disease could help prevent severe illness and death.