Congo’s Mpox Crisis

For the second time in 2 years, a long-overlooked virus poses a global threat. Can it be contained?

In late September 2023, a 33-year-old man who co-owned a bar in Kamituga, a remote mining city in the Democratic Republic of the Congo (DRC), developed lesions on his genitals and a fever. He first sought help from a doctor, who gave him an injection, and then from a traditional healer, who applied ointments and performed an enema. But the lesions kept spreading, eventually appearing on most of his body.

His relatives convinced the man to come to the family home in the city of Bukavu—a trip that takes 6 hours on a good day and twice as long during the rainy season, when much of the road turns to mud. Health workers there swabbed his lesions, and a lab in Kinshasa, the capital, confirmed the man had something rarely seen in that part of DRC: mpox, a painful and occasionally fatal disease caused by a relative of the smallpox virus.

A January report from the Bukavu branch of the DRC’s Ministry of Public Health, obtained by Science, called this man the “index case”—the first known patient—in the epidemic of mpox now sweeping the country. The report said he fell ill after visiting Kisangani, a city a few provinces away. It did not explain how he might have become infected, but the genital lesions suggested it was through sexual contact.

Eleven of the 98 people whom the bar owner was in contact with before leaving Kamituga also developed symptoms, the report says, and seven of them also “fled”—to Bukavu, a city of 1.3 million in South Kivu province, and on to Goma, the capital of North Kivu province, and neighboring Rwanda. In the months that followed, cases surfaced in all of those places, as well as in Burundi, Uganda, Kenya, and Zambia. The virus also made it across the DRC to Kinshasa and travelers took it to Thailand, Europe, and the Americas.

Science met the man, who asked not to be identified, in November. The infection had been horrendous, he said: “I felt like my genitals were going to fall off.” He initially thought someone might have put a curse on him, and, once he learned it was mpox, wondered whether it might be from his visit to the Kisangani zoo. It outraged him when people on social media criticized him by name for bringing the disease to Kamituga. “I felt offended and even wanted to sue,” he said. A child in Kamituga had mpox at the same time and could have been the real index case, he argued.

Regardless of his exact role in spreading the disease, Kamituga—where many of the first patients were miners and sex workers—has become the epicenter of the burgeoning epidemic, which the World Health Organization (WHO) in August labeled a Public Health Emergency of International Concern (PHEIC).

The crisis came less than 2 years after the outbreak of another mpox variant that started in Nigeria and eventually sickened more than 100,000 people in 120 countries, most of them men who have sex with men (MSM). It too led WHO to declare a PHEIC from July 2022 until May 2023, when vaccinations, education campaigns, and the buildup of immunity in people at high risk led the outbreak to subside.

The successive epidemics are a dramatic turn of events for what was long one of the most neglected viral diseases in the world.

Mpox is endemic in large parts of the DRC, but the past 50 years, outbreaks mainly affected children in remote villages tucked into the rainforest in the western and central regions of the DRC, each time jumping from an animal “reservoir,” sometimes followed by limited transmission between people. The spread would typically burn out after a few months because the affected communities were small and relatively isolated.

The outbreak that began in Kamituga sparked something entirely new: an epidemic, with cases soaring in places that had never seen mpox before. Combined, endemic and epidemic spread in the DRC have caused more than 47,000 suspected cases in the first 11 months of the year, compared with only 14,626 in 2023.

Now, an aggressive effort is underway to bring the disease under control. Donors, working closely with WHO and UNICEF, have flown in hundreds of thousands of mpox vaccine doses. Aid groups and local clinics, funded largely by foreign governments and United Nations branches, have set up treatment centers where suspected patients can be tested and, if infected, kept in isolation for several weeks. “Mpox existe,” posters across the francophone country warn, encouraging people to seek care if they have fevers and the characteristic skin lesions.

Graphic: 'From endemic to epidemic'

Mpox has been endemic in the Democratic Republic of the Congo for decades. The virus occasionally jumped from wild animals to people, mainly children, sometimes followed by some human-to-human transmission. Since September 2023, however, the country has seen rapid epidemic spread between humans, as have neighboring Burundi and Uganda. (Rwanda, Kenya, and Zambia have reported smaller case numbers. See the graphic "From endemic."

But a November visit by Science to the Kivus and Kinshasa revealed the challenges are enormous. There are far too few vaccine doses for the population at high risk, and their distribution throughout the country—more than half the size of the European Union—has been agonizingly slow. Children, who account for half the cases and are most at risk of severe disease and death, are not being vaccinated at all.

Diagnostics are scarce: Only 22% of suspected cases this year have been confirmed. People sometimes leave treatment centers before their test results are in, potentially exposing others. Hygiene and education efforts are spotty, and surveillance largely relies on people seeking care, rather than on teams actively hunting for cases.

Several government agencies are involved in the response, sometimes creating confusion about who is in charge. “It’s really crazy to see what is happening,” says Placide Mbala, an epidemiologist and veteran mpox researcher at the National Institute of Biomedical Research (INRB) in Kinshasa, who co-led a team studying the outbreak in Kamituga. “Sometimes when you go to meetings, you are working with people who believe that they know better than you what to do. They are trying to copy and paste what they learned from books.”

Whether the DRC can get mpox under control is a pivotal question for both the country and the world. If not, it will become a permanent additional stress on the country’s fragile heath system. And exported cases will pose a continual threat to other countries.

Mbala thinks the spread can at least be dramatically slowed, just as the earlier, global epidemic in MSM was. “We know where the disease is more prevalent and where we are seeing more human-to-human transmission,” he says. “It would be easy in those places to set up good surveillance and good diagnostics, and very quickly, we can stop this disease. … It’s just a matter of willingness and money.”

The mpox virus was discovered in 1958, far from Africa, when Asian monkeys in a Copenhagen lab became ill. Scientists isolated the virus and named the disease “monkeypox,” a misnomer: African squirrels and other rodents are the likely “reservoir host” of the virus. The lab monkeys presumably got infected because international animal traders caged several species together. (The name was changed to mpox in 2022 to avoid stigma.)

The first human case did not surface until August 1970: a 9-month-old boy from the DRC’s Équateur province, which is still an mpox hot spot. Doctors initially thought his lesions were caused by smallpox and sent samples to a Moscow lab, which correctly diagnosed the disease. The boy recovered but died of measles before leaving the hospital.

Investigators noted that in contrast with his parents and 10 siblings, who did not get mpox, the boy was not vaccinated against smallpox. They guessed immunity to smallpox protected against mpox as well—a hunch that would prove correct. After smallpox was declared eradicated in 1980, vaccinations ended worldwide and mpox reports began to increase. (There had only been 59 cases in all of Africa until then, 80% of them in the DRC.) In 1996–97, a startling outbreak near the town of Katako-Kombe had 511 suspected cases, most of them due to human-to-human transmission.

Once researchers started to actively look for cases, they realized mpox was far more widespread than believed. In a landmark 2010 study, a team led by then–INRB Director Jean-Jacques Muyembe and epidemiologist Anne Rimoin of the University of California, Los Angeles reported finding 760 cases over a 2-year period in Katako-Kombe and eight neighboring health zones. “It was putting the cards on the table and saying, ‘Hey, listen, this is a problem,’” Rimoin says.

Still, mpox was rare, most people recovered, and mild cases were easily mistaken for chickenpox, so doctors often ignored it. And the DRC had many more pressing health problems, including measles, cholera, tuberculosis, and malaria. “It’s unfair to say, well, we all knew an epidemic was going to happen, and you guys didn’t do anything about it,” Rimoin says.

Infographic: 'A long-neglected virus on the move'

Since the world’s first mpox case was found in Équateur province in 1970, the Democratic Republic of the Congo (DRC) has seen more cases than any other country. Until recently, most were of a variant named clade Ia, but during the past 15 months, clade Ib has exploded in the eastern part of the country—which never saw an mpox outbreak before—and has spilled over to neighboring countries. See the graphic "A long-neglected virus on the move."

Then came the Kamituga outbreak, described in an April preprint by a large, international team of researchers that included Mbala, Rimoin, and Muyembe. (Nature Medicine published the paper online in June.) During the first 5 months of the epidemic, the study found, 29% of the 108 confirmed cases were sex workers. Genetic sequencing revealed the virus was distinct from the variant in endemic regions, clade I, so that was renamed Ia, while the lineage circulating in Kamituga—which had been found in two patients more than a decade earlier—was christened Ib.

Kamituga’s “highly mobile” population of miners and sex workers could easily spread the disease far and wide, the researchers warned: “We advocate for swift action by endemic countries and the international community to avert another global mpox outbreak.”

When a different mpox variant, clade IIb, spread from Nigeria to MSM communities in Europe 2 years ago—first taking off at a gay festival—swift action brought it to heel. That did not happen in Kamituga. “It’s like two outbreaks on two different planets,” says Laurens Liesenborghs, a clinician based at Belgium’s Institute of Tropical Medicine who works in the town and helps lead the research effort. “There was a window of opportunity to stop this outbreak in its tracks, but then there was no money, there was no attention.”

Pigs, goats, and chickens roam the grounds of the Kamituga general hospital, a campus of one-story buildings separated by courtyards that was built in 1935, during the Belgian colonial era. Patients wash their own laundry and sprawl it across hospital lawns or hang it from the trees to dry. No functioning kitchen exists, so families provide food for hospitalized relatives. But in the rear of the large facility, which features a glorious view of the lush Mitumba mountain range, is a state-of-the-art mpox treatment center. It was opened in July by the Alliance for International Medical Action (ALIMA), a Paris-based group that has its operational headquarters in Senegal and is largely run by Africans. At that point, five nurses at the hospital had contracted mpox.

Today, staff are required to wear masks, gowns, gloves, hair nets, and shoe coverings before they visit patients with suspected mpox, who are housed in a makeshift plastic hut with private rooms. A hospital lab run by INRB has a GeneXpert machine, a user-friendly portable device that can run the polymerase chain reaction to detect viral DNA in lesions or blood samples—a process that only takes a few hours.

If patients test positive, they are isolated in a different area that has brick buildings and a large tent, where they receive meals and treatment. Outreach workers try to identify patients’ contacts to check their health, but that can be difficult, especially when transmission involved sex. When Science visited, two male patients, both miners, mainly had genital lesions, but they insisted they had not had sex for months. That’s not uncommon, says Grace Kamifula, one of the center’s doctors. “The men are shy and it’s about morality,” he says. “About 80% of them never say the truth about how they contracted mpox.”

Few patients treated at the center have died. “Since we’ve opened, we’ve taken care of 300 sick people and lost only two,” says Fiston Nepa, one of ALIMA’s lead doctors at the center. A study of 427 confirmed cases seen at the hospital between May and October, posted on medRxiv by the Kamituga research team, put the mortality rate at 0.5%—much lower than the 3% to 10% seen in past DRC outbreaks. (The figures do not include four pregnancy losses.)

By November the outbreak in Kamituga appeared to be waning, and its character had shifted. “Before, there were many cases that were infected through sexual contact,” says INRB epidemiologist Guy Mukari, who runs the lab here. Now, many sex workers have recovered from mpox, and some have been vaccinated. But infected adults have spread the virus to their children. Most patients in the unit were babies, sharing beds with their mothers, who had been vaccinated. The one sex worker receiving treatment says she didn’t know there was a vaccine until she came to the center.

Kamituga’s treatment center is well equipped and staffed. Not so in many other centers in the Kivus, including one in Lwiro, an agricultural town 45 kilometers from Bukavu that has seen 870 patients since it opened in August. Diagnoses are difficult here because the center does not have a GeneXpert machine; it relies on a lab in Bukavu, and results can be slow to arrive, says Alfred Bisimwa, the doctor running the center. “Sometimes we get results back after patients have left.” (Lowering the cost of testing might help. Advocates are pressing Cepheid, the producer of the machines, to drop the price of testing cartridges from $20 to $5.) And suspected cases are housed together, which means people without mpox could become infected while they wait for a diagnosis. “It’s frustrating,” Bisimwa says.

Shortages of beds, blankets, and food have let up, but the center still regularly runs out of antibiotics, blood for transfusions, and oxygen, and there’s no electricity at night. “We’re used to losing patients, but it’s different when you know you could have saved them if you had enough resources,” Bisimwa says, adding that the staff are underpaid and overworked. “And in those moments, it’s difficult to motivate ourselves to go back to work.”

Still, the mood in the men’s tent is one of dormitory camaraderie. Some sit outside and chat with visitors through a fence. One 40-year-old miner catches a wad of bills that a friend throws in from the other side. He’s constantly scratching the more than 100 lesions on his face, torso, arms, and feet. “I heard that it can be transmitted through sex, but the difference between me and the other men here is I don’t have it on my genitals,” he says. Had his groin been affected, he doesn’t see how he could have made the long motorbike ride from the mine where he works to Lwiro.

Yet another ALIMA-run treatment center is in the Rusayo internal displacement camp, in the outskirts of Goma, which houses more than 80,000 people who fled rebel incursions in North Kivu. The camp consists of crowded, closely spaced tents, a good place for mpox to spread between people even without sexual contact. At the center, 10 children suspected of having mpox are housed in a single large tent.

Results from samples taken 2 days earlier have just come back from an INRB lab in Goma. Two of the children are positive, says nurse Jean-Claude Ndayambaje, and he enters the tent to find them. He comes back empty-handed. “The confirmed cases are back in the community,” Ndayambaje says. “Some of our cases, they run away when they feel better.”

Vaccines are a cornerstone of the DRC’s containment efforts. Resurrecting the smallpox vaccine is out of the question because it can cause serious side effects, especially in people who have compromised immune systems. Instead, the country relies on an mpox vaccine called modified vaccinia Ankara (MVA), produced by the Danish company Bavarian Nordic. The government’s plan is to give shots first to contacts of cases, creating “rings” of immunization around them. The plan also targets sex workers, their clients, and health care personnel.

Early one morning in Kalingi, a neighborhood in Kamituga, a team of outreach workers is moving between wood shacks, taking health histories from five men and women ages 24 to 64 who had come in close contact with an mpox patient—a wife, a son, and a neighbor. Then, a nurse sputters up on a motorbike, a cooler containing mpox vaccine slung over his shoulder. All agree without hesitation to receive a shot. Ideally, they’ll get a second dose a month later.

Kamituga health workers have also teamed up with the “queen mother” of sex workers, who runs something of a parlor in her home where women and clients share beers and gossip and bring her disputes to resolve. “When we started promoting the vaccine, many people thought it would kill them, but because I was the leader and the first to take it, everyone started to believe in it,” the woman says.

But the city has too few doses to make a serious dent in its epidemic. Until recently, the DRC’s cash-strapped government deemed mpox far too rare, and not nearly lethal enough, to warrant buying and administering vaccines. Even the global outbreak in MSM didn’t change that calculus. In early 2023, the U.S. Agency for International Development (USAID) wanted to send 50,000 doses of MVA, then already widely in use among MSM in other countries. But the government was not eager to take them, and the donation stalled. “They didn’t believe mpox is a very big problem,” says INRB virologist Steve Ahuka. “Don’t forget that we have had this disease since 1970.”

Even today, things are moving slowly. DRC regulators did not approve MVA for mpox until June—5 years after the U.S. Food and Drug Administration did so—and the first donations did not arrive until September. By October, when vaccinations began, the country of 110 million people only had 265,000 doses, donated by USAID, the EU, and Bavarian Nordic.

Kamituga, with almost a quarter-million people, at first received 6,300 doses. But given shortages elsewhere, the government decided to take half that stock back and give everyone just one of the two doses. “It seemed like the vaccine had legs and walked away,” Nepa says. A small freezer at the general hospital holds the 800 remaining doses. Even health care workers have not received a second dose, says Nepa’s boss, Dally Muamba. “Why did they do that?” Muamba asks, touching his heart. “That’s a big question.”

Distributing the available doses is proving hard. The DRC is chaotic, with gridlocked traffic in its cities and few flights between them. Many roads are unpaved and so narrow they only allow passage by motorbike—and rain can turn them into quagmires. River boats are slow. As of 28 November, only 55,266 vaccine doses had been used, according to Health Ministry records—“behind what we would have expected or wanted to see at this point,” says Andrew Jones, deputy director of immunization at UNICEF, which plays a central role in procuring and delivering mpox vaccine to the DRC.

Children under age 18, who are most at risk of dying if they get mpox, are not getting vaccinated at all. WHO and European regulators both have said MVA can safely be given to children but concerns about who will assume liability if harm occurs, along with regulatory hurdles, have delayed its use.

In mid-November the DRC received another donation of 122,000 doses of MVA, and 640,000 more are “awaiting shipment,” says UNICEF, which has plans to purchase millions more doses for African countries in collaboration with Gavi, the Vaccine Alliance. Japan has promised to donate just over 3 million doses of another vaccine, LC16m8, but again, bureaucratic issues have hampered shipment. (LC16m8, a one-dose vaccine, causes a lesion that leaves a scar, which some experts worry could reduce its uptake and even lead people to shun MVA as well.)

All of the donations combined won’t meet goals set by the Africa Centres for Disease Control and Prevention to control the mpox outbreak on the continent. Its response plan calls for 10 million doses to be distributed by February 2025. For the DRC, that would be a massive increase from current numbers, and a dramatic scale-up of the distribution effort.

At the Vijana hospital in downtown Kinshasa, a crowd and several journalists—including a Japanese TV crew—have gathered at one of the city’s three mpox treatment centers, where the provincial health minister and UNICEF officials will make a visit this morning. Mpox, once a neglected disease, has become the infection du jour.

“I’m really astonished that mpox is in Kinshasa,” says Jerry Vandam, the doctor running the center. The city never had an mpox outbreak until 2023. Researchers began to detect a few sporadic cases of clade Ia, the longtime variant in endemic regions, in August 2023. The number of so-called APOBEC3 mutations in the virus—which accumulate as it circulates in people—showed there was little human-to-human transmission at the time. Instead, the virus popped into humans from animals repeatedly.

But in July, cases started to rise, and human-to-human transmission has now become the sole driver of both Ia and Ib in Kinshasa. So far this year, the city has had more than 1,200 suspected cases, most of them in an area that has “a high density of professional sex workers,” Mbala and coworkers wrote in a 16 November preprint. Adults made up 80% of the patients.

The presence of the virus in the capital—with 17 million people and a busy international airport—“represents a significant threat for regional and international dissemination,” Mbala and his co-workers wrote in the preprint. But in Kinshasa, too, vaccine is in short supply. Only one of the city’s 20 health areas has received doses to date, says Emeryrodolphe Mungyengi, the top doctor for the local health ministry. “It’s a question of support from our partners,” Mungyengi says.

Why mpox has twice burst out of the forest to cause major epidemics, in part through sexual contact, has perplexed researchers. Until the 2022 epidemic in MSM, some even doubted it could be spread through sex. “This is what keeps me up at night,” says Andrea McCollum of the U.S. Centers for Disease Control and Prevention, who has studied mpox in the DRC for 15 years. “Why now, and why in these two places?”

There is no evidence that mutations have made the virus more transmissible, says Andrew Rambaut, an evolutionary biologist at the University of Edinburgh. Instead, he thinks it simply found its way into communities where many people have multiple sexual partners in a short time frame—enough to spark an epidemic and sustain rapid spread. The MSM epidemic traces back to a Nigerian outbreak that started in 2017 in Port Harcourt, an oil and natural gas hub that attracts men from many places and sex workers. In Kamituga and Kinshasa, sex work has been a driver as well.

Martine Peeters, a virologist at the University of Montpellier who has hunted for viral reservoirs in the DRC for 5 years with Ahuka, compares mpox to HIV, which also smoldered in rural Africa for decades before reaching the gay community and exploding. “If it arrives at the right time at the right place, it becomes an epidemic,” Peeters says.

In the DRC, deforestation, human movement, the growth of cities, increased hunting of animals, malnutrition, and decreasing immunity may have all contributed to epidemic spread as well, McCollum says. But, she adds, “I’ll be honest with you, I tell people my crystal ball is broken. I did not foresee what has become of mpox.”

Nor can anyone predict what comes next. If containment fails in the Kivus, the virus may well establish a permanent human reservoir there, Ahuka notes, which could give it a chance to evolve and become even more transmissible. It could also lead to reservoirs in new animal species, Rimoin notes, the way SARS-CoV-2 established itself in white-tailed deer in the United States during the COVID-19 pandemic.

Despite the many obstacles, some are hopeful the DRC can stop the epidemic spread of mpox. “It’s easy to contain the disease,” says Nepa, who believes that Kamituga will soon see cases plummet, thanks to the isolation of cases, education, immunity in people already infected, and vaccination. Rimoin is optimistic, too. “We can certainly mitigate the impact of mpox and the global spread,” she says.

But some researchers say the response should not be limited to the epidemic hot spots in big cities. The rural pockets of endemic disease that have been neglected for decades have higher mortality rates and could always ignite another epidemic. Vaccination efforts might save more lives by concentrating on children in endemic areas, researchers say. In an October paper in The Lancet Global Health, Yale University epidemiologist Gregg Gonsalves, Rimoin, and Mbala calculated that over a 1-year period, vaccinating 80% of children under age 15 in rural areas would decrease DRC cases by 54% and deaths by 71%. But it would take a whopping 26.6 million doses.

Ahuka sees another problem. The international mobilization to help the DRC battle mpox is “really great,” he says, but it’s a double-edged sword. “Support us to take care of ourselves,” Ahuka says. “If support is long-standing, it becomes a disease, we become dependent. And we’re suffering from that.” Rapid case finding, diagnostics, and vaccination are all essential, he says. “The Congolese should now integrate these interventions as routine, because mpox will never end.”