Marburg virus is a rare but severe pathogen that causes hemorrhagic fever with an average fatality rate around 50%. It belongs to the same viral family as Ebola and spreads to humans primarily through contact with Egyptian rousette bats. While outbreaks have been relatively small compared to other infectious diseases, they can be devastating: fatality rates in individual outbreaks have ranged from 24% to 88%, depending on how quickly patients receive supportive care.
How the Virus Spreads
The natural home of Marburg virus is the Egyptian rousette bat, a fruit bat found across Africa. The virus lives in the bats’ saliva, urine, and feces without making them visibly sick. People typically become infected through prolonged exposure in caves or mines where these bats roost. Once a person is infected, the virus can spread to others through direct contact with blood, bodily fluids, or contaminated surfaces and materials.
Person-to-person transmission requires close contact. During one well-studied outbreak in the Democratic Republic of the Congo, researchers estimated a secondary attack rate of about 21% among contacts of confirmed cases, meaning roughly one in five people in close contact with a sick person became infected. That rate is lower than many respiratory viruses, but the severity of the disease makes even limited spread dangerous. The virus can also persist in semen for months after a person recovers. In early studies, semen samples showed a 70% positivity rate within the first seven months after illness, and the virus was detected as late as 203 days after symptom onset. One of the earliest documented cases of sexual transmission occurred in 1967, when a survivor’s wife contracted the disease after intercourse.
Symptoms and How the Disease Progresses
The incubation period ranges from 2 to 21 days, though symptoms most commonly appear around 8 to 10 days after exposure. The illness begins abruptly with high fever, severe headache, and muscle pain.
Four to five days after symptoms start, the disease often shifts to what clinicians call the “wet” phase: intense nausea, vomiting, and watery diarrhea that can lead to rapid dehydration. By days 5 through 7, many patients develop a distinctive rash of flat and raised red lesions, usually on the neck, trunk, and arms. The skin in these areas may eventually peel or flake off.
From there, outcomes diverge sharply. In nonfatal cases, fever tends to break and patients begin improving around day 6. In fatal cases, severe complications develop early, and death typically occurs between days 6 and 16 from multi-organ failure or septic shock. The speed of this progression is one reason early, aggressive supportive care makes such a large difference. Rwanda’s 2024 outbreak had a 23% fatality rate, while Equatorial Guinea’s 2023 outbreak reached 88%.
How the Virus Attacks Cells
Marburg virus particles are filamentous, meaning they’re long, thread-like structures rather than the round shape most people picture when they think of a virus. They can also appear branched, U-shaped, or ring-shaped. This unusual structure is a hallmark of the filovirus family.
Once inside the body, the virus enters cells through a specific process. It gets taken up into small compartments within cells, where enzymes strip away a protective cap on the virus’s surface protein. This exposes a binding site that locks onto a cholesterol transport protein called NPC1, which sits on the inner membranes of these compartments. That binding triggers a shape change in the viral protein that lets the virus fuse with the cell membrane and release its genetic material inside. It’s the same entry mechanism Ebola uses, which is why researchers studying one virus often make breakthroughs relevant to the other.
Treatment Options
There is no approved treatment specifically for Marburg virus disease. Care currently centers on managing symptoms: replacing fluids lost to vomiting and diarrhea, maintaining blood pressure, and treating secondary infections as they arise. This supportive care alone can significantly reduce fatality rates when started early.
Several experimental therapies are in development. A monoclonal antibody called MR191-N has shown the most striking results in animal studies, providing up to 100% survival when given within five days of infection. Antiviral drugs originally developed for other viruses are also being tested. During Rwanda’s 2024 outbreak, remdesivir was offered experimentally both as a preventive measure for people recently exposed and as a treatment in combination with a monoclonal antibody therapy called MBP091. Other antivirals that have shown promise in animal studies include favipiravir and galidesivir, which works by disrupting the virus’s ability to copy its genetic material.
Vaccine Development
No vaccine is currently approved, but candidates are progressing through clinical trials. The most advanced is cAd3-Marburg, a single-dose vaccine built on a modified chimpanzee cold virus that delivers a key Marburg surface protein to train the immune system. It completed Phase 1 testing and is now in a Phase 2 trial evaluating safety and immune response in healthy adults. The urgency of recent outbreaks has accelerated this timeline, though a licensed vaccine is still likely years away.
Outbreak History and Current Status
The virus was first identified in 1967 when laboratory workers in Marburg and Frankfurt, Germany, and in Belgrade, Yugoslavia, became ill after handling tissues from imported African green monkeys. That outbreak infected 31 people and killed seven. Since then, outbreaks have occurred sporadically, mostly in sub-Saharan Africa.
The largest and deadliest outbreak struck Angola in 2005, killing 88% of the 252 confirmed cases. More recently, smaller outbreaks have appeared with increasing frequency: Ghana in 2022, both Equatorial Guinea and Tanzania in 2023, Rwanda in 2024, and Ethiopia in late 2025. Ethiopia’s outbreak, declared over in January 2026, involved 14 confirmed cases and nine deaths.
Most outbreaks remain geographically contained because the virus requires close contact to spread. Imported cases to countries outside Africa have been extremely rare. A traveler returning to the United States from Uganda in 2008 was diagnosed with Marburg virus disease and survived, and a similar imported case occurred in the Netherlands the same year.