Updated October 08, 2024 at 13:17 PM ET
This story was updated on October 8 at 1:17 p.m.
Rwanda is now a test lab for an experimental vaccine against the Marburg virus.
The African nation is in the grips of one of the world’s largest Marburg outbreaks, with 56 cases and 12 deaths so far. Currently there is no approved vaccine or treatment for Marburg patients.
Rwandans are so nervous that Minister of Health Sabin Nsanzimana took time at a Sunday press conference to answer a frequently asked question: If a passenger on a motorcycle taxi uses the helmet provided by the driver, could they catch Marburg if the previous helmet user happened to be infected?
His advice: “As a precaution, anyone using a shared helmet should clean it before use.”
Other countries are concerned as well. The U.S. has told embassy staff in Rwanda to work remotely for at least the next several days. The U.S. Centers for Disease Control and Prevention is alerting physicians in the United States about the situation and will start screening all travelers who have recently been in Rwanda upon arrival in the U.S. — and are urging people to reconsider nonessential trips to Rwanda.
The silver lining to this frightening outbreak, say public health officials, is the opportunity to test a vaccine that has shown promise in primates.
Rwanda has received 700 doses and started vaccinating health care workers and people who have been in close contact with a Marburg patient. The experimental vaccine is being developed by the U.S.-based Sabin Vaccine Institute, a nonprofit. The U.S. Department of Health and Human Services invested over $235 million in developing the vaccine and the donated doses were manufactured under the nonprofits contract with the U.S.
"If the clinical trials are able to show efficacy, meaning that they are effective, that obviously is a huge leap forward,” says Gary Disbrow, the director of the Center for the Biomedical Advanced Research and Development Authority (BARDA) at HHS.
The World Health Organization has deemed the “risk of this outbreak as very high at the national level, high at the regional level and low at the global level.” It is the first outbreak in Rwanda of the Marburg virus, which has a fatality rate that can reach as high as 88%.
A bat spillover
The virus comes from fruit bats and is in the same family as the Ebola virus.
Jennifer McQuiston is the deputy director of the division at the CDC that studies lethal viral diseases. She says whenever she hears about patients showing up with symptoms like a high fever and blood in vomit or stool, it sets off alarm bells in her mind. A whole host of serious viruses can cause what’s called a viral hemorrhagic fever — think Ebola and yellow fever.
“When this was confirmed as Marburg, it solidified those concerns,” she says.
There are a number of factors, she and other experts say, that make this outbreak particularly concerning — and give a sense of urgency to the vaccine trial.
A lot of cases all at once
McQuiston says one of the first things that caught her attention is just how many Marburg patients there were — more than two dozen — when the outbreak was first announced by Rwandan health authorities on September 27.
“We're concerned about the number of cases that got diagnosed very quickly,” she says, noting that it can take as long as 21 days between exposure and the onset of symptoms. “That indicates to us it's probably been circulating for a few weeks.”
This could have happened because Rwanda has never reported Marburg cases before, which would mean that health care professionals weren’t initially thinking about testing patients for it. That’s likely because many of the symptoms — like a high fever — can easily be caused by other ailments.
Indeed, Rwandan officials said one of the early patients had both malaria and Marburg at the same time. They only diagnosed the man with Marburg after malaria treatments did not resolve the symptoms.
“Knowing what's happening is the first important step so you can put in the right prevention measures,” McQuiston says. “That is happening now.” Rwanda has set up separate medical units to treat Marburg patients so that other people in the hospital are not exposed, similar to what was done during past Ebola outbreaks.
Medical professional are advised put on impermeable gowns, respirators and double gloves when dealing with a possible Marburg patient and Rwandan officials have set up handwashing facilities so the public can help prevent the virus from spreading further.
The other worry with the high number of cases is that the virus “might have had time to spread in ways they haven't even begun to understand yet,” says McQuiston. In past outbreaks, the virus comes from a bat likely through contact with its urine or other excretions — or from eating the same fruit that an infected bat nibbled, for example.
But a few of the past outbreaks didn't have a clear bat link, so there’s speculation that there could be an intermediate host — for example, a bat gives the virus to a monkey or pig who then passes it on to a human who consumes the meat. And a person who's infected can spread the virus to another person. However, past outbreaks have been relatively small, in part because patients die so quickly and the virus does not transmit through the air.
Health care workers are hard hit
A second major reason for concern is that upwards of 70% of the Marburg patients in Rwanda, so far, are health-care workers.
Since the virus can spread from person to person through contact with bodily fluids — blood, vomit, stool, saliva and even semen — McQuiston’s guess is that missing the initial diagnosis meant the health-care workers in the past few weeks were likely caring for Marburg-stricken individuals without suiting up in protective gear.
Now Rwandan officials are taking action. They’ve identified and are monitoring hundreds of contacts of Marburg patients to see if they’ve contracted the virus. Their response has drawn praise — and some questions.
Dr. Abraar Karan, an infectious disease postdoctoral researcher at Stanford University, says that when he heard Rwandan health officials tell people with symptoms to go to their nearest health center, he found it a “risky” approach. He worries that patients might take public transit, putting others in danger — and showing up at a hospital waiting room could put other patients and clinical staff at risk of exposure until a diagnosis is confirmed.
Instead, Karan says, “it would be important for community health workers to ... get ... to people's homes.” That way they can wear protective gear when collecting samples for testing and help arrange transport to a unit designated specifically for Marburg patients, he says.
Rwandan officials are now advising people with symptoms to call a helpline.
It’s in the capital
The Marburg virus — named for the German city where scientists first became ill with the disease in 1967 when handling monkeys from Africa — is typically found in Egyptian fruit bats who live deep in caves. Cases usually occur in remote areas — someone might go into a cave as a miner or to collect bat guano to use as fertilizer and be exposed to the virus.
But cases in this outbreak aren't confined to a remote area. Instead, patients have been identified in seven of Rwanda’s 30 districts — and in the capital city of Kigali.
Karan says the worry is that through human transmission, the virus could quickly spread onward to other places. “It's already hit a hub, a transportation hub,” he says. “You have a lot more movement between countries and between continents.” It’s easy for someone who has been exposed but is not yet symptomatic to jump on a bus or plane without realizing they are carrying the virus.
Indeed, WHO confirmed in a statement that at least one person who was in contact with a Marburg patient has already traveled — to Belgium. The statement said “appropriate response measures have been implemented.”
Rwandan officials are already doing contact tracing and have called for limiting attendance at funerals for Marburg patients to 50 people. This restriction echoes the Ebola crisis, when family members who cleaned the body or had other physical contact with the corpse were at risk of exposure to virus-laden bodily fluids.
“Rwanda is a place where a lot of United States health-care workers and clinicians go to provide aid or do mission trips. And so I think tracking who's been over there and making sure that they are monitoring their health when they come back, is an important thing that we're actively doing right now,” says the CDC’s McQuiston.
Testing a vaccine and a treatment
The lack of vaccines and treatments designed specifically to help Marburg patients is a major challenge.
“With Marburg it's very hard to study the vaccines without cases. And so in a setting like this, you may be able to deploy the vaccines and figure out vaccine effectiveness,” says Karan.
That’s exactly what Rwanda has decided to do. There are Marburg vaccines in Phase I and II development. And a monoclonal antibody is being tested as a treatment for people who have Marburg.
In addition to the 700 vaccine doses that were donated to Rwanda, HHS's Disbrow says "a limited number [of the monoclonal antibody treatments] have been released to treat a handful of individuals" in Rwanda. The U.S.'s HHS put an $129 million to help Mapp Biopharmaceutical develop the monoclonal antibody.
Disbrow says WHO and Rwandan officials are working to initiate a randomized clinical trial where the monoclonal antibody and Gilead's remdesivir would be tested as treatments. If that goes forward, additional doses would be donated.
"We always will hold back a little bit for national preparedness in case there's an imported case through travel or we have to medevac U.S. citizen for treatment, and if healthcare workers need to be vaccinated," he says.
A reason for optimism
Although infectious disease experts say are worried, they say they also feel some reassurance because of Rwanda's robust health-care system.
“We believe that Rwanda has the capacity and the ability to stop this outbreak very quickly,” says Brian Chirombo, the World Health Organization’s representative to Rwanda.
But McQuiston admits that Rwanda’s health system is juggling a lot, with an ongoing mpox outbreak as well. “Our [CDC] staff are stretched quite thin as we think about, ‘How do we mount dual responses?’ And I can only imagine that in Rwanda — where both of these outbreaks are occurring, but they also have malaria and a lot of other health concerns — that it creates a situation that, I think, stresses their health systems,” she says.
Karan says it will likely take several weeks before it’s clear where this outbreak is heading.
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