A new strain of the mpox virus spreading quickly along the eastern border of Democratic Republic of Congo is "incredibly worrying", say health officials monitoring its spread.
The virus, which can cause lesions across the whole body, is making some people very ill and can be deadly.
The current outbreak has been driven by sexual transmission but there is evidence this strain can also be passed on through close skin-to-skin contact.
Global health experts say the new variant risks cross-border and international spread of the virus, with one calling it the "most dangerous strain yet".
A worldwide epidemic of mpox in 2022 was brought under control by vaccinating vulnerable groups.
But there is poor access to vaccines and treatments in DR Congo and local health officials are warning the virus could reach other countries.
"The disease can go through airports. A person with lesions can go through borders because there are no controls," said Leandre Murhula Masirika, at the health department in South Kivu province - one of the worst affected areas in DR Congo.
"I'm very afraid it's going to cause more damage."
'Risk of spread'
Cases of mpox, formerly called monkeypox, have been on the rise in the African country for decades.
Official figures from the World Health Organization (WHO) show there have been nearly 8,000 cases this year in DR Congo, including 384 deaths - almost half of these among children under 15.
An outbreak in South Kivu province, near the border with Rwanda, Burundi and Uganda, is causing particular concern.
Lab testing of virus samples from the area recently found the new mpox strain, which contains mutations that appear to help it circulate among humans.
In the mining town of Kamituga, where the strain is thought to have originated among sex workers in September 2023, cases are rising. Those now being infected include schoolchildren, healthcare workers treating mpox patients and entire households.
The new strain has been detected in several cities along the border, including Goma, which borders Rwanda.
The WHO said it represented "a renewed risk of cross-border and international spread which may potentially lead to an increased risk of severe illness".
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