On Sept. 30, 2023, an anxious father brought his 5-year-old son to the hospital in Kamituga, a muddy, bustling town carved out of the thick forest in the eastern Democratic Republic of Congo. The boy had a high fever and oozing sores on his torso and face.
Nurses diagnosed chickenpox. They admitted him to the pediatric ward, part of a sprawl of low-slung brick buildings that date to the colonial era, and tried to manage his fever.
Days passed, and the child’s health did not improve. His fever climbed higher, the lesions spread, blistering even the soles of his small feet.
Perplexed, the pediatric staff called Dr. Steeve Bilembo, who was managing urgent care. He and a trusted nurse colleague, Fidèle Kakemenge, examined the boy and named, and then quickly eliminated, possibilities: Not chickenpox, not measles, not rubella, not a bad case of dermatitis — he would be improving by now if he had any of those ailments.
The spreading sores meant it wasn’t malaria or typhoid or cholera, the diseases afflicting other children in the crowded ward.
“And then at one point, we said, ‘Could it be mpox?’” Dr. Bilembo recounted. “Although we have never seen it — only in books.”
They looked it up, and quickly confirmed that the child had all the symptoms of mpox. Yet it made no sense. Although mpox was first discovered in Congo in 1970, and has been endemic in the country ever since, the disease circulated in remote villages in the center of the country — 2,000 kilometers (more than 1,200 miles) away. It was unknown in the east.
How could a boy who had never left Kamituga have mpox?
It was the start of a medical mystery that would reveal swift and startling changes in a virus once considered a familiar foe, lead to the declaration of a global public health emergency and draw scientists from around the world on a dayslong journey along a muddy, rutted track that is the only way to reach Kamituga.
Fifteen months later, the new strain of the virus has spread to six other countries through East and southern Africa, according to the Africa Centres for Disease Control and Prevention, and individual cases have turned up in Europe, Asia and North America, as well. The virus seems to have adapted to spread more easily and quickly between people. More than 62,000 cases of mpox have been reported in Africa this year, three-quarters of them in Congo.
An estimated 1,200 people have died of mpox, which kills about 2.5 percent of those it infects in Congo. Some of the infected have only a dozen lesions and mild fever, but people with severe cases have thousands of lesions, including in the eyes and mouth. Small children with lesions lining their throats can struggle to eat or even breathe.
The World Health Organization declared the outbreak a global emergency in August, and authorized the use of a first-ever vaccine and a rapid test for mpox in an effort to try to contain the spread.
But that day in early October 2023, it was just Dr. Bilembo and Mr. Kakemenge. They scraped fluid from the child’s lesions and sent it off for testing in Goma, the only city in the east with a lab that could do it: two days to travel 175 miles on the back of a motorbike courier, and then a daylong boat trip up Lake Kivu. Long before the results finally came back two weeks later, confirming that Kamituga Reference Hospital had its first-ever case of mpox, they were already convinced.
They had taped big sheets of paper to the wall in an empty supply room, and stayed up all night mapping out all the ways the child might have been infected. Mpox transmission in Congo was believed to start most often with an infected animal, which passed the virus to a hunter, or to a child through a bite. But the child’s family said they did not hunt, and he had not been bitten.
Then, Dr. Bilembo said, the father mentioned that he had seen an ailment similar to his son’s, not too long before. The father is a traditional healer, who uses natural remedies and magic spells, and he told the hospital staff he had been called to cure a local businessman of an affliction after he was cursed by jealous competitors.
The father told Mr. Kakemenge that the curse had caused the man to break out in oozing lesions that so disfigured him he looked “like a monster.” He said he had tried to heal the man by rubbing his limbs with an ointment he made.
When they heard this, Dr. Bilembo and Mr. Kakemenge took a marker and drew a dotted line on their paper from the infected child to the businessman with the curse. The man, named Julien, was the 35-year-old owner of a popular nightclub in Kamituga called Mambegeti, the word for the buckets in which they sold bottles of beer. Julien also ran an adjoining business, a maison de tolérance, as it is known here — a collection of bedrooms rented by servers at the bar who also sell sex.
About a dozen women worked there, most of whom Julien was said to have recruited from other regions of Congo, Rwanda or Burundi, even a few from Tanzania and Uganda. They came to this hardscrabble town of about 300,000 people because it’s surrounded by gold mines. When the miners are paid, they come into Kamituga ready to spend 75 cents for some time behind the thin cotton curtains that separate the women’s rooms.
The next day contact tracers from the hospital went to the nightclub to inform its employees that a suspected mpox case had been traced to the house. They learned that Julien had been ill for a couple of weeks and, the day before, had left for Bukavu, the regional capital.
The club manager said several of the young women who worked there also had fevers and lesions. So, as it happened, did he. The men who run the maisons de tolérance typically collect a “tax,” having sex with all the women who worked in their bars, Mr. Kakemenge explained.
Everyone who worked there was asked to come to the hospital for testing, and many were soon admitted as presumed cases. One of the women had been making the rounds through crowded prayer halls, seeking a cure for the disease, Dr. Bilembo recalled, as he rubbed his hands over his face remembering the epidemiological nightmare they saw unfolding.
He and his colleagues switched into emergency mode, activating infection control protocols they had learned during Ebola and cholera outbreaks. But they had no protective equipment, just bars of soap, he said.
As for trying to trace how mpox had arrived in Kamituga? Julien, their index case, had vanished, and the trail had gone cold.
They didn’t know that in Bukavu, Julien had gone to stay with his uncle — a man who happened to be a doctor, and a regional public health official. He made an on-the-spot diagnosis for his nephew.
“He said, ‘You have mpox,’” Julien recalled in an interview last month. Slight, soft-spoken and stylish in black sweats and sandals, he agreed to meet me in the lounge of a down-market hotel to tell his version of events. He asked to be identified only by his first name, to protect his privacy.
The doctor called a team from the local hospital to collect samples from Julien’s sores, and sent them to Kinshasa for testing. Julien agreed to be isolated in the hospital when his diagnosis was confirmed, but he refused any treatment.
“The truth is that it was sorcery: Someone put this curse on me,” he said. “And it was the traditional healers who cured me.”
Julien recovered about five weeks after he first fell ill. When we met, he had just a faint hint of a few scars on his face and trouble with his left eye, which had a milky, misshapen pupil and blurry vision. Severe cases of mpox often cause ocular complications. Julien hides his damaged eye behind gilt-trimmed designer sunglasses, which he wears even indoors.
Back in Kamituga, the child slowly recovered as well.
By the time confirmation came from the far-off lab that it was mpox, these first mysterious cases had become an epidemic.
The community outreach workers found dozens of cases among sex workers, and soon, among the itinerant gold miners who provide most of their business. As word spread through the town, more and more people began to turn up at the hospital with symptoms — at least 50 a week. The staff struggled to isolate them because the hospital couldn’t feed them all, and sick patients left to search for meals in town. Soon staff members began to fall ill as well; two nurses each lost the vision in one eye after severe cases of mpox.
But these mpox patients had cases that were different in one key way: Many of the adults infected had lesions mostly or solely on their genitals. They were profoundly painful.
In Kinshasa, researchers at the National Institute of Biomedical Research sequenced the genome of the virus infecting Kamituga patients, and realized it differed significantly from the one that had caused mpox outbreaks in Congo for years.
They labeled it a new subclade, a sort of genetic cousin of the familiar virus, and scrambled to try to understand how it differed — were the genital lesions a sign of sexual transmission? How was the virus now moving so quickly between people?
By the middle of this year, the new subclade had turned up in neighboring countries — Rwanda, Burundi, Uganda — traveling with migrant workers from the mining town. The international spread of the virus brought the sudden glare of attention — and some help — to Kamituga, where some things have changed.
Now, the hospital has an efficient mpox treatment center, run by the Alliance for International Medical Action, also known as Alima, where patients are isolated and cared for through their illness. Those patients are no longer mostly sex workers and miners; the virus is moving through the general population, and hitting children hard.
There is a small laboratory where mpox tests undergo genetic analysis on site: Cases are confirmed within an hour or two, instead of a week or more.
Until a few weeks ago, not a single person in Congo had ever been vaccinated against mpox; now about 50,000 people have, including most of the sex workers in Kamituga. (Business has nevertheless declined precipitously, said Sifa Kungunja, who heads an informal union of women in the trade — although she makes sure that any woman who has lesions stops work for a month, she added.)
And a team of Congolese and international epidemiologists and virologists has set up shop at the hospital, running a comprehensive research project that tracks patients for months after their recovery to try to better understand the behavior and the impact of this new variant.
Kamituga is a wildly difficult place to try to conduct a scientific investigation: The daytime electrical current is barely strong enough to power a single lightbulb, and it can take three days to drive the 125 miles to Bukavu, the nearest hub for transport of scientists and their research samples. For eight months of the year, rain falls so hard each day that visibility is less than a meter, and Land Rovers meant to carry refrigerated boxes of virus samples sink up to their windows in the soft red mud.
The scientific work is still in early stages. “There are so many things about this virus we don’t know,” said Dr. Dally Muamba, who runs the Alima operation in Kamituga.
Here are some of them:
Is the new subclade (called Clade Ib) truly sexually transmissible — spread through semen and vaginal secretions as H.I.V. is — or infecting people through the close physical contact that comes with sexual intercourse? Researchers have found the virus in semen, but have yet to establish if it’s being transmitted that way.
It’s not clear why more than half of cases are now children. Most seem to catch the virus from close contact with parents or other family members who may themselves have shown few signs of the disease, said Dr. Papy Munganga, the epidemiologist running the patient study.
Are more children affected these days because the virus has already burned through many of the adults who were vulnerable? Older people who were vaccinated against smallpox have some immunity. Is the new vaccination campaign already having an impact? (The vaccine being used is approved only for adults.)
Or is the new variant, established in the population, now racing through children who are more vulnerable because so many are malnourished, with immunity lowered by malaria and other infections?
There is still considerable stigma around the disease because of its association with sex workers; Dr. Munganga wonders if adults are perhaps not seeking treatment unless they are very ill, but mothers are bringing in sick children.
It’s not clear what effects the virus is having on pregnant women — but in Kamituga, few women who became infected have carried their pregnancies to term. Women in their first trimester almost invariably miscarry, Dr. Bilembo said, while women in later stages have stillbirths. The fetuses they carried, and the placentas, are often pocked with lesions.
And most fundamentally, there is the question of how the virus came to Kamituga. Julien is known as the “first case,” a label he firmly rejects. The researchers agree with him: He may well have been infected by someone who had a milder case and never sought care from the health care system, or whose symptoms were misdiagnosed as a sexually transmitted infection. The virus may have been circulating in Kamituga for months before it came to the attention of Dr. Bilembo and his colleagues.
The U.S. Centers for Disease Control and Prevention has been partnering with Congo’s government on mpox surveillance since 2010, and samples collected from three isolated cases in the east of the country back in 2015 turned out, when they were sequenced recently, to be genetically similar to the new subclade.
So it’s not truly new, the way it felt to Dr. Bilembo and Mr. Kakemenge when they considered that first sick child. The precursor of this virus may have been circulating in animals for years, said Dr. Placide Mbala, who heads the epidemiology division of the national research institute and runs its pathogen genomics laboratory.
But somehow, not long ago, it made a jump, perhaps from a rodent to a person, and that person happened to be linked to the heavily populated sexual network of Kamituga. And in that environment, the virus seems to have mutated in ways that have facilitated human-to-human transmission of a kind the country had never seen.
Today everyone in Kamituga is familiar with the disease and on the lookout for signs. Here, it’s known as mambegeti, after Julien’s nightclub. He has since shut it down, and opened a new club, called Mercato, in an effort to rebrand. He says business is fine.
“They say people here were the first in the country to be vaccinated, maybe first in the world,” said Marie Bayaya, who braids hair on the front step of a wooden shack hair salon not far from the entrance of the hospital. “It’s because of mambegeti that our town is known, now.”
