Mpox - formerly known as monkeypox - can spread through close contact and while it is usually mild, it can be fatal in rare cases.
It causes flu-like symptoms and pus-filled lesions on the body.
An emergency committee met earlier on Wednesday to advise WHO director-general Tedros Adhanom Ghebreyesus on whether the disease outbreak constitutes a "public health emergency of international concern," or PHEIC.
"The detection and rapid spread of a new clade of — World Health Organization (WHO) (@WHO) #mpox in eastern #DRC, its detection in neighbouring countries that had not previously reported mpox, and the potential for further spread within Africa and beyond is very worrying.In addition to other outbreaks of other clades…August 14, 2024
PHEIC status is the WHO's highest level of alert and aims to accelerate research, funding and international public health measures and co-operation to contain a disease.
"It's clear that a co-ordinated international response is essential to stop these outbreaks and save lives," Tedros said.
The outbreak in DR Congo began with the spread of an endemic strain, known as clade I.
But a new variant, clade Ib, appears to spread more easily through routine close contact, including sexual contact.
It has spread from DR Congo to neighbouring countries including Burundi, Kenya, Rwanda and Uganda, triggering the action from the WHO.
"The detection and rapid spread of a new clade of mpox in eastern DRC, its detection in neighbouring countries that had not previously reported mpox, and the potential for further spread within Africa and beyond is very worrying," Tedros added.
Tedros said on Wednesday that WHO had released $US1.5 million ($A2.3 million) in contingency funds and plans to release more in the coming days.
LIVE: Media briefing with — World Health Organization (WHO) (@WHO) @DrTedros on outcome of the #mpox Emergency Committee meeting https://t.co/oghcXCgqclAugust 14, 2024
WHO's response plan would require an initial $US15 million, and the agency plans to appeal to donors for funding.
Earlier this week, Africa's top public health body declared an mpox emergency for the continent after warning that the viral infection was spreading at an alarming rate, with more than 17,000 suspected cases and more than 500 deaths this year, mainly among children in DR Congo.
A total of 13 countries have reported cases.
Professor Dimie Ogoina, chair of WHO's mpox emergency committee, said all members unanimously agreed that the current upsurge of cases is an "extraordinary event," with a record number of cases in DR Congo.
Vaccines and behaviour change helped stop the spread when a different strain of mpox spread globally, primarily among men who have sex with men, and the WHO declared an emergency in 2022, which it ended 10 months later.
In DR Congo, the transmission routes need further study, the WHO said.
