WHO declares mpox a global public health emergency for second time in two years

The World Health Organization on Wednesday declared mpox a global public health emergency for the second time in two years, following an outbreak of the viral infection in the Democratic Republic of Congo that has spread to neighboring countries in Africa.

A “public health emergency of international concern,” or PHEIC, is the WHO’s highest level of alert, and it can accelerate research, funding and international public health measures and co-operation to contain the disease.

Earlier this week, Africa’s top public health body similarly declared mpox, formerly known as monkeypox, an emergency after warning that the viral infection was spreading at an alarming rate.

More than 17,000 suspected mpox cases and 517 deaths have been reported on the African continent so far this year, a 160% increase compared to the same period last year, the Africa Centers for Disease Control and Prevention said. Cases have been reported in 13 countries.

Mpox has two distinct viral clades, I and II. Both versions can spread through close contact with an infected person or via direct contact with infected animals or contaminated materials.

The outbreak in Congo began with the spread of clade I, a strain that is endemic in central Africa and known to be more transmissible. Clade I can cause more severe infections; previous outbreaks have killed up to 10% of people who got sick.

A new version of that strain, clade Ib, is now spreading and appears to be more easily transmissible through routine close contact, including sexual contact. It has spread from Congo to neighboring countries, including Burundi, Kenya, Rwanda and Uganda, triggering the action from the WHO.

“It’s clear that a coordinated international response is essential to stop these outbreaks and save lives,” said WHO Director-General Tedros Adhanom Ghebreyesus.

A strain of clade II, meanwhile, was responsible for the global spread of mpox in 2022. Infections from that clade are far milder than clade I — more than 99.9% of people survive, according to the U.S. Centers for Disease Control and Prevention. But it’s still capable of causing severe illness, particularly in people with weakened immune systems.

The version of the virus that prompted the WHO to declare a public health emergency in 2022 was known as clade IIb. It spread largely through sexual contact among men who have sex with men.

The WHO ended that emergency declaration 10 months later. In the U.S., mpox cases have declined considerably since their peak in 2022. Average daily cases fell to zero in the week ending Aug. 1.

However, given the virus’ spread in the Democratic Republic of Congo and its bordering countries, the CDC asked doctors last week to be on alert for mpox among people with characteristic symptoms who have recently spent time in the area. No cases of clade I have been reported outside central and eastern Africa, the agency said, but it warned about the risk of further transmission.

Mpox usually starts with a rash that can look similar to chickenpox, syphilis or herpes. The rash typically progresses to small bumps on the skin, then to blisters that fill with whitish fluid. The illness is often accompanied by fever, headache, muscle aches, back pain, low energy and swollen lymph nodes.

A vaccine for mpox is available in the U.S. but not generally available in the Democratic Republic of Congo.

The CDC recommends that people who are exposed to the monkeypox virus — or who belong to groups with an elevated risk of infection, such as men who have sex with men — receive two doses of the vaccine. It is effective against both clades of mpox.