Marburg virus: Everything you need to know about this rare, deadly infectious disease and the outbreaks

April 12, 2023
A team of experts from the World Health Organization assists community members during a 2017 Marburg outbreak in Uganda. Here the team burns bedding and clothing from a patient who died of Marburg. The illness is frightening because there are no vaccines or treatments. Mortality rates are very high. Photo by Benjamin Sensai, courtesy of the World Health Organization.
A team of health experts assists with a 2017 Marburg virus disease outbreak in Uganda. Here the team burns bedding and clothing from a patient who died of Marburg. Photo by Benjamin Sensai, courtesy of the World Health Organization.

United States health officials have issued warnings urging health workers and travelers to be on guard against outbreaks of the deadly Marburg virus in Africa, but so far, there are no cases in the U.S.

Marburg is currently spreading in two separate outbreaks in Equatorial Guinea and Tanzania. Tanzania is a popular tourist destination both for safaris and mountain climbers who are venturing to Mount Kilimanjaro.

Officials with the U.S. Centers for Disease Control and Prevention (CDC) are not actively screening travelers for the disease as they arrive in the U.S., but they are sending text messages to people who have recently traveled to Tanzania and Equatorial Guinea. The messages explain the symptoms that travelers should watch for and instruct people to contact local health department officials and their doctors if they develop symptoms within 21 days after returning from Africa.

Marburg is a hemorrhagic fever virus and is similar to the Ebola virus. There are no treatments or vaccines, so the death rate for those who become infected can be as high as 80%, said Dr. Michelle Barron, senior medical director of infection prevention and control for UCHealth and one of the top infectious disease experts in Colorado.

Barron said the risk of Marburg spreading to the U.S. is extremely low, but she and other health experts are keeping a close eye on the African Marburg virus outbreaks (in 2023) since global travel now makes it much easier for viruses to spread around the world.

“It’s on our radar. We’re paying attention to the outbreaks because you never know if they will escalate,” said Barron, who is also a professor at the University of Colorado School of Medicine on the Anschutz Medical Campus.

UCHealth Today consulted with Barron to answer your questions about Marburg.

Why is Marburg so frightening?

“Mortality is high,” Barron said. “It’s upwards of 80%, and there’s no treatment or vaccine for Marburg. It can also spread easily via contact with blood or bodily fluids. So these outbreaks have elements that raise alarms in terms of infection prevention.”

Barron and her team set up alerts this spring for patients who have returned from Equatorial Guinea and Tanzania.

Few Americans travel to Equatorial Guinea, but Tanzania is a popular destination for U.S. travelers.

“That made us pay more attention to these outbreaks,” Barron said.

Where are Equatorial Guinea and Tanzania?

Equatorial Guinea is located on the western coast of Africa. Tanzania is in eastern Africa. Many people confuse Equatorial Guinea with Papua, New Guinea, which is close to Australia and Indonesia, and Guyana in South America.

The current Marburg outbreaks are taking place in Africa, not elsewhere in the world.

Map of Marburg virus outbreaks. Map: U.S. Centers for Disease Control and Prevention (CDC).
Map of Marburg virus outbreaks. Source: U.S. Centers for Disease Control and Prevention (CDC).

How do people get Marburg?

Like Ebola and many other viruses, Marburg spreads in animal populations and can jump to humans.

“It’s typically associated with fruit bats,” Barron said.

The illness then spreads in people through direct contact with bodily fluids.

“This can be contact with saliva, blood, semen, emesis (from vomiting) or diarrhea,” Barron said.

Family members or health workers who care for people with Marburg can be infected if they are exposed to bodily fluids then touch their eyes, nose or mouth. Marburg can also spread through sexual contact with an infected person.

The disease is most transmissible once a person becomes sick rather than during the incubation period.

“If health care workers are not wearing appropriate personal protective equipment (PPE), then risk of transmission of the virus is high,” Barron said.

Should the average person in the U.S. be worried about Marburg?

No. The average person in the U.S. doesn’t need to worry about Marburg.

“The likelihood of us seeing a patient is next to zero. But if we did, we have many trained people with a lot of experience to manage this appropriately,” said Barron. “These outbreaks are still very much contained to places far from the U.S.”

What should I do if I have traveled recently to Africa, and I’m having some symptoms?

If you have traveled recently to Tanzania and Equatorial Guinea, and you have some symptoms, follow the CDC guidance. Call your doctor and report your symptoms to your local health department.

“If you have traveled to these places or you have come into contact with someone who is sick and recently traveled to these places, then contact your doctor,” Barron said. “Marburg is extraordinarily uncommon, but we want to keep an eye on people.

“So, if you are concerned, come in. Let’s say you had traveled to one of these places and you have some symptoms. We will ask you additional questions about what you were doing and where you were,” Barron said. “It’s not a reason to panic. But it’s good to be aware.”

What if I’m planning a trip to Tanzania? Should I cancel it?

Individuals need to make their own decisions about travel, of course.

But Barron said travelers are unlikely to be exposed to Marburg.

“It’s like all things. You should be aware of Marburg (and other illnesses) when you are traveling,” Barron said.

But these types of viruses are very rare, and even for people who live in Tanzania and Equatorial Guinea, the chances of infection are very low.

Here is specific advice from CDC experts about how to take precautions if you are traveling:

  • Avoid contact with blood and bodily fluids.
  • Avoid exposure to people who are sick.
  • Do not touch the body of a person who has died, and be cautious about attending a funeral or burial.
  • Avoid contact with fruit bats and non-human primates. Avoid mines and caves.
  • After returning from an area experiencing a Marburg outbreak, monitor your health for at least 21 days and seek medical care immediately if you develop symptoms of Marburg.

(Learn more about how to get necessary travel vaccines and how to prepare for trips outside of the U.S.)

Is Marburg a new virus? I haven’t heard of it before.

No. Marburg is not new. It’s been around for decades, but is less well known that Ebola. Marburg was first recognized in 1967.

“It’s in a family that we call viral hemorrhagic fevers. Ebola is the best known. And some people may have heard of Lassa,” Barron said.

How long is the incubation period between exposure to Marburg and sickness?

Marburg has a much longer incubation period than more common infectious diseases like COVID-19 and the flu, Barron said.

“The average is about 7 to 10 days, but it can be up to 21 days. And so, there’s a really long incubation period. And that makes this challenging,” she said.

How transmissible is Marburg?

“Marburg is highly transmissible,” Barron said. “It’s more transmissible in what’s known as ‘the wet phase’ rather than ‘the dry phase.’ During the dry phase, people have fever, chills, body aches, that sort of thing. The wet phase is when people start having issues with bleeding, vomiting and diarrhea. That’s when they’re most infectious.”

Can people spread Marburg if they don’t have symptoms?

No. A person with Marburg is not contagious until symptoms appear, according to CDC experts.

Is the spread of Marburg similar to the spread of COVID-19?

No. The virus that causes COVID-19 is a respiratory virus. It spreads through respiratory droplets. These droplets can stay suspended in the air or can contaminate objects and remain infectious for a short time. People can spread COVID-19 when they sneeze or cough. It is also possible for people who are asymptomatic to spread COVID-19. Marburg, on the other hand, spreads less easily than COVID-19 and is typically associated with contact with blood or bodily fluids. But it is also much deadlier.

Are there effective treatments and vaccines for Marburg?

No. That’s one of the biggest worries about Marburg. Unlike Ebola — for which there are now some treatments and vaccines — there are not good therapies or preventive vaccines for Marburg.

What is happening with the Marburg outbreaks now?

The Marburg outbreak in Equatorial Guinea was confirmed in February when health workers investigated a cluster of deaths in two villages in the west African country. So far, 10 deaths in Equatorial Guinea have been linked to Marburg.

Health officials in Tanzania announced the outbreak there in March. As of early April, experts have confirmed 8 cases of Marburg and five people in Tanzania have died, according to CDC officials.

How are health care workers in the U.S. preparing for possible cases of Marburg?

Health care workers are very experienced at dealing with infectious diseases.

As with COVID-19, using masks and proper personal protective equipment — also known as PPE — is essential.

Barron said health care workers need to be especially careful if a person is in the later phases of the illness.

“It’s similar to Ebola. In the later phase of a person’s illness, health care workers are more likely to have contact with bodily fluids and secretions. Marburg is not airborne. It’s the blood and saliva that are concerning. When in doubt, don PPE.”

About the author

Katie Kerwin McCrimmon is a proud Coloradan. She attended Colorado College thanks to a merit scholarship from the Boettcher Foundation and worked as a park ranger in Rocky Mountain National Park during summers in college.

Katie is a dedicated storyteller who loves getting to know UCHealth patients and providers and sharing their inspiring stories.

Katie spent years working as an award-winning journalist at the Rocky Mountain News and at an online health policy news site before joining UCHealth in 2017.

Katie and her husband, Cyrus — a Pulitzer Prize-winning photographer — have three adult children and love spending time in the Colorado mountains and traveling around the world.