Rwanda faces its first Marburg virus outbreak. As of late September, 62 cases and 15 deaths had been reported as of October 17, most of them among healthcare workers in Kigali, the capital.
More than 800 contacts of infected people have been followed up in an effort to detect infection early and prevent further transmission, two of whom traveled to Belgium and Germany but were declared cured. As of October 21, no new cases or deaths had been reported in six days, but the threat of the outbreak has not disappeared.
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What is Marburg virus and what are its symptoms?
The Marburg virus comes from the same family of viruses as the virus that causes Ebola, which is “one of the most deadly pathogens known to infect humans,” according to a perspective article in New England Journal of Medicine.
The disease can cause similar symptoms, such as fever, chills and headaches, as well as muscle aches and pains. Within a few days, people may experience a rash on the chest, back, and stomach. They may also experience nausea, vomiting and diarrhea.
Marburg virus damages blood vessels and interferes with blood clotting, which can cause blood in the vomit and stool, as well as bleeding from the nose and gums. In extreme cases, this infection causes internal bleeding and sepsis, which can lead to organ failure and death.
Where do outbreaks usually occur?
The virus was first identified in 1967, after outbreaks in the German cities of Marburg and Frankfurt, and in the Serbian capital, Belgrade. These cases were linked to laboratory experiments to improve the polio vaccine involving African green monkeys (Chlorocebus aethiops) from Uganda.
Since then, the virus has typically caused several outbreaks per decade, often in East African countries such as Uganda, as well as the neighboring Democratic Republic of the Congo (DRC), which is in Central Africa.
This virus was identified in Guinea, West Africa, in 2021. Since then, this outbreak has occurred every year in various parts of the continent. For example, Ghana experienced its first outbreak in 2022 and Equatorial Guinea experienced its first case last year. Egyptian fruit bat (Rousettus aegyptiacus) live in various parts of Africa and can carry the Marburg virus, said Emma Thomson of the University of Glasgow, UK.
The reasons why outbreaks appear to be occurring more frequently are unclear. This may be due to increased surveillance of cases and people having more frequent contact with Egyptian fruit bats, Thomson said. Miles Carroll at Oxford University thought the same thing.
People can contract the Marburg virus if they visit caves or work in mines where bats live. This may be happening more often, but increasing deforestation is also bringing humans closer to these animals, Carroll said.
How deadly is it?
Mortality rates from the Marburg virus have varied widely from 24 percent to 88 percent in previous outbreaks, similar to the 25 percent to 90 percent mortality rates seen with Ebola.
The range in death rates may be due to differences in countries’ capacity to detect cases and hospital resources in each country, Thomson said.
On October 20, World Health Organization director general Tedros Adhanom Ghebreyesus issued a statement saying the agency was impressed by the level of critical care people in Rwanda were receiving. He referred to two people with multiple organ failure who were on life support and receiving mechanical ventilation. “We believe this is the first time a Marburg virus patient has been extubated in Africa,” he said. “These patients may have died in previous outbreaks.”
The ongoing outbreak in Rwanda is the third largest so far, both in terms of cases and deaths. This occurred after an outbreak in Congo in 1998 to 2000, when 154 cases were recorded and 128 people died, and an outbreak in Angola in 2004 to 2005, when 252 people were infected and 227 people died.
Who is most at risk?
There have been only a few known cases since the Marburg virus was identified, making it difficult to know who is most at risk of severe infection, Thomson said. But those with weakened immune systems, such as the elderly or pregnant, may be more vulnerable, he said.
Only a few cases have been reported during pregnancy, but the European Center for Disease Prevention and Control says the infection is generally more severe during pregnancy, when the body’s immune function changes.
Ebola is also more severe in older people, so something similar may be true for Marburg virus, Thomson said.
How to catch it?
Genetic sequencing of cases in Rwanda has revealed that the virus jumped from animals, such as Egyptian fruit bats or African green monkeys, to humans only once in the ongoing outbreak, the country’s health minister wrote on Twitter on October 20.
Therefore, the remaining transmission occurs between humans. This can happen if virus particles in the blood or other body fluids enter another person’s body through broken skin or through the eyes, nose, or mouth. Funeral ceremonies where people touch the corpse of an infected person also increase the risk of infection.
There is no evidence that the Marburg virus spreads through droplets expelled when an infected person breathes, talks, coughs or sneezes, Carroll said.
How is the treatment?
There are no medications specifically approved to treat Marburg virus. People who require hospital treatment are usually given intravenous fluids to replace water lost due to vomiting and diarrhea. Pain relievers can also help relieve discomfort.
In 2021, researchers found that combining the antiviral drug remdesivir with antibodies against the virus protected four out of five rhesus monkeys from infection at a lethal dose. On October 15, Rwanda began testing this approach in humans.
Is there a vaccine?
There is no approved vaccine against the Marburg virus, but researchers are trialling an experimental vaccine in Rwanda, where 1,700 doses have been administered and 669 doses were administered as of October 14.
This vaccine regimen consists of a single shot containing an engineered genetic sequence of adenovirus, which causes flu-like symptoms. Researchers have modified the adenovirus to contain the protein that the Marburg virus uses to infect cells. Once injected, the adenovirus enters cells and produces copies of the viral proteins, so the immune system can learn to recognize them.
Vaccinating contacts of infected people may be the most efficient use of vaccine doses to slow the spread of the virus, Thomson said.
What is the risk of this outbreak leaving Rwanda?
Rwanda has increased testing of contacts of infected people who are under quarantine, but there remains the potential for the virus to spread, Carroll said.
“The possibility of local spread in this region to neighboring countries is currently very concerning,” said Thomson. Rwanda borders Uganda, Tanzania, Burundi and Congo. The virus could also spread further in Africa or even cause occasional cases elsewhere in the world if people travel to the region, he said.
In early October, the Hamburg train station platform was closed after two passengers suspected of having Marburg symptoms who had recently visited Rwanda were on board a train from Frankfurt. They were later confirmed not to have contracted the virus.
Countries need to warn people traveling from Rwanda about the risks and signs of Marburg infection, Carroll said. If someone later develops symptoms, they can be immediately tested and quarantined before an outbreak occurs elsewhere, he said.
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