In May 2023, the World Health Organization issued a statement declaring the end of mpox — formerly known as monkeypox — a public health emergency. Less than a year later, the agency was forced to withdraw, and a much more sedate epidemic is growing across much of sub-Saharan Africa.
Statistics show that since January, more than 15,000 cases of mpox and 461 deaths have been reported on the African continent. The disease has spread from countries such as the Democratic Republic of Congo (DRC), where mpox has long been endemic, to 13 other African countries: Rwanda, Kenya, Burundi and Uganda, where it had previously had no effect.
In the eyes of scientists like Boghuma Titanji, an assistant professor of infectious diseases at Emory University who studies MPox outbreaks, this novel, deadlier outbreak is a consequence of global health authorities failing to act adequately last time.
It was the summer of 2022 when the spread of mpox first raised alarm. Suddenly, the virus, which had always been mostly confined to parts of West and Central Africa, suddenly spread worldwide. Between early 2022 and December 2023, there were 92,783 confirmed cases MPox in 116 countries, leading to 171 deaths.
Despite those numbers, the perception of it as a public health threat quickly faded. “Ninety-five percent of cases in the 2022 outbreak were in men who have sex with men, reporting exposure through sexual contact or close contact with another infected person,” says Titanji. “It was a very targeted outbreak, which allowed for vaccination to be prioritized within that network.”
Countries in the global north have fought effectively to suppress the outbreak within their borders. Meanwhile, Titanji says, ramping up virus surveillance among African nations, which have been struggling with a steady rise in mpox cases for the past four decades, soon fell to the bottom of the priority list, allowing a potentially more problematic variant to emerge undetected.
Mpox comes in two main subtypes, clade 1 and clade 2. Clade 1 is thought to be up to 10 times more deadly, especially among population groups with weakened or developing immune systems, such as children under 5, pregnant women, and immunocompromised individuals. That’s the strain of virus behind this novel outbreak, and why infectious disease scientists are so concerned. (A separate outbreak spreading in South Africa among people living with HIV is thought to be linked to clade 2.)
“The global epidemic in 2022 was clade 2, with a mortality rate of less than 1 percent,” says Jean Nachega, a Congolese infectious disease physician and associate professor of medicine at the University of Pittsburgh. “Now we’re talking about a strain that could have 10 percent mortality.”
While the previous outbreak was mostly confined to homosexual populations, the data suggests that the new strain is also being transmitted much more widely, perhaps initially through sexual networks and then passed on to family members. Last month, Nachega and others published a paper in the diary Nature’s Medicine shows how the MPox epidemic began in the compact mining town of Kamituga in eastern Democratic Republic of Congo with sex workers, then spread to nearby Rwanda, Uganda and Burundi as infected people returned home to visit their families.