The rapid spread of mpox, formerly called monkeypox, in African countries constitutes a global health emergency, the World Health Organization declared Wednesday.
This is the second time in three years that the WHO has designated an mpox epidemic as a global emergency. It previously did so in July 2022. That outbreak went on to affect nearly 100,000 people, primarily gay and bisexual men, in 116 countries and killed about 200 people.
The threat this time is deadlier. Since the beginning of this year, Congo alone has reported more than 14,000 mpox cases and 524 deaths. Those most at risk include women and children under 15.
"The detection and rapid spread of a new clade of mpox in eastern DRC, its detection in neighboring countries that had not previously reported mpox, and the potential for further spread within Africa and beyond is very worrying," said Dr. Tedros Adhanom Ghebreyesus, the WHO's director-general, using an acronym for the Democratic Republic of Congo.
The outbreak has spread through 13 countries in Africa, including a few that had never reported mpox cases before. On Tuesday, the Africa Centers for Disease Control and Prevention declared a "public health emergency of continental security," the first time the organization has taken that step since the African Union granted it the power to do so last year.
"It's in the interests of the countries, of the continent and of the world to get our arms around us and stop transmission as soon as we can," said Dr. Nicole Lurie, executive director for preparedness and response at the Coalition for Epidemic Preparedness Innovations, a nonprofit that finances vaccine development.
Facing the threat of global spread, the Centers for Disease Control and Prevention has urged clinicians and the public in the United States to be alert for the virus.
The WHO's designation of a "public health emergency of international concern" is intended to prompt member countries to begin preparing for the virus's appearance and to share vaccines, treatments and other key resources with poorer nations.
"We need concerted international action to stem this recent, novel outbreak," said Gregg Gonsalves, an epidemiologist at Yale University who served on the WHO's mpox committee in 2022.
The outbreak that year stayed mostly within tight sexual networks among gay and bisexual men. A combination of behavioral changes and vaccination tamped down the spread.
In the United States, for example, the toll dropped to about 1,700 cases last year from more than 30,000 in 2022.
The version of mpox that has been circulating in Congo has always been more virulent and currently has a death rate of about 3%, compared with 0.2% in the 2022 outbreak. The infection can produce fever, respiratory symptoms, muscle aches and swollen lymph nodes, as well a rash on the hands, feet, chest, mouth or genitals.
Until recently, it spread mainly through consumption of contaminated meat or close contact with infected animals and people. Most of the deaths have been in children, who in this region of Africa are already beset by malnutrition and infectious diseases including cholera, measles and polio.
Should the outbreak spread globally, children in developed countries are likely to be less vulnerable to severe illness, experts have said.
Last year, for the first time, scientists discovered sexual transmission of this version of mpox, with cases split about equally among young men and women. According to genetic analyses, sometime around September, the virus gained mutations that enabled it to spread more readily among people. It has done so partly through heterosexual prostitution.
This viral type has not surfaced outside Africa. Overall, there have been more than 17,500 presumed and confirmed mpox cases in 13 countries, according to Africa CDC. Most of the cases and deaths have occurred in Congo.
Given the rapid spread, the declaration of a global health emergency was justified, said Anne Rimoin, an epidemiologist at the University of California, Los Angeles, who served on the 2022 mpox panel.
"I think we learned a great deal about the speed with which this virus can spread," she said.
Amid rising numbers, Congo has approved two mpox vaccines: a Japanese product called LC16 and Jynneos, a vaccine made by Bavarian Nordic that was used in 2022 in the United States and Europe. But Congo has yet to institute an immunization plan.
On Aug. 9, the WHO invited vaccine manufacturers to apply for an emergency use listing, a prerequisite for international groups such as Gavi, a global vaccine alliance, to purchase and distribute the shots in low-income nations.
Bavarian Nordic has donated 15,000 doses of Jynneos to be distributed in African countries. But that is a tiny fraction of the 10 million doses needed to control the outbreak, according to Africa CDC.
LC16 was used in Japanese children in the 1970s. Clinical trials funded by the Coalition for Epidemic Preparedness Innovations are now evaluating whether Jynneos can protect children and people who have already been exposed to the virus, Lurie said.
The organization is also supporting the development of a new mRNA vaccine made by BioNTech that would protect against mpox and related viruses, such as smallpox.
"This outbreak has been smoldering for quite a long time, and we continually have missed opportunities to shut it down," Lurie said. "I'm really glad that everybody is now paying attention and focusing their efforts on this."