The World Health Organization on Saturday reported 12,569 mpox cases and 581 related deaths in the Democratic Republic of Congo this year to November 12, the highest annual figure ever recorded.
The infectious disease, formerly known as monkeypox, was first identified in humans in 1970 in the DRC.
It has been endemic for years in several West and Central African countries, where outbreaks often began when the virus was transmitted to humans from infected animals.
All but four of the DRC's 26 provinces reported infections, "with new cases in geographic areas that had previously not reported mpox, including Kinshasa, Lualaba, and South Kivu", the WHO said.
The WHO is concerned about the transmissibility of a variant and said it was working with the Congolese health ministry to assess the situation.
A spike in infections last year in Europe and the United States, outside the disease's endemic areas, prompted the WHO to declare a public health emergency of international concern, the highest alarm it can sound, in July 2022.
It ended the alert in May this year but advised populations to remain vigilant.
The global outbreak has mainly affected men who have sex with men and who have recently had sex with one or multiple partners, according to the WHO.
Contaminated objects can also spread the disease.
The first symptoms are fever, headaches, muscle pain and back pain during the course of five days.
Rashes subsequently appear on the face, palms of hands and soles of the feet, followed by painful lesions, spots and finally scabs.
The disease usually heals by itself after two to four weeks. It is most serious for children, pregnant women and people with compromised immune systems.
A total of 91,788 cases and 167 deaths have been reported in 116 countries and territories from January 2022 to October 31 this year, the WHO says.