How Worried Should You Be About Marburg Virus?
“With no therapeutics and a high mortality rate, future outbreaks and a pandemic remain possible. Therefore, urgent consideration of Marburg virus disease and ways in which to prevent a pandemic due to this virus is essential.”
- Chunfu Zheng, Ph.D., Associate Professor, University of Calgary
“Geography is destiny.”
- Abraham Verghese, American physician, author, Professor for the Theory and Practice of Medicine, Stanford University Medical School
On February 13, 2023, the World Health Organization (WHO) confirmed an outbreak of Marburg virus in Equatorial Guinea. The virus, which is native to Africa and a member of the same filovirus family as the Ebola virus, causes a highly life-threatening infection. In this Germ Gems post, I put this emerging viral infection in perspective summarizing the key features of Marburg virus, the disease it causes, and who’s at risk.
What is the nature of Marburg virus hemorrhagic fever (Marburg HF)? Scientists first recognized Marburg virus in 1967 when outbreaks of hemorrhagic fever occurred simultaneously in research laboratories in Marburg and Frankfurt, Germany and in Belgrade Yugoslavia (now Serbia). At least 31 people (laboratory workers and their contacts) became ill, and seven deaths were reported. Imported African green monkeys or their tissues were the source of this laboratory-triggered outbreak.
Subsequently, scientists characterized Marburg virus as a genetically unique zoonotic RNA virus of the filovirus family—a family whose only other members are the five species of ebola virus. Marburg virus and ebola virus share many features, including causing a gruesome hemorrhagic disease that kills more than half of its victims, a person-to-person transmission, and an ability to stir worldwide panic. (My first Germ Gems post, “How About a Moonshot to End Ebola Virus Infections?,” on July 20, 2019, tells the story of ebola virus.)
Who is at risk? The virus is native to the African continent. The African fruit bat, Rousettus aegyptiacus, is the reservoir host for Marburg virus. This bat species is widely distributed across Africa but just when and how the virus spilled over into human and other animal hosts is not known. Since the initial description of laboratory-related Marburg virus disease in Germany and Serbia in 1967, the WHO reported outbreaks of Marburg HF in seven African countries: Angola, Congo, Ghana, Guinea, Kenya, Uganda, and most recently, Equatorial Guinea.
Travelers to these African countries can be at risk. In 2008, a Dutch tourist developed fatal Marburg HF after returning to the Netherlands from Uganda and that same year an American traveler to Uganda developed Marburg HF after returning home—he survived. Both travelers had visited a well-known cave inhabited by fruit bats.
Signs and symptoms of Marburg HF. Marburg HF is a highly virulent infection. After an incubation period of 5-10 days, sudden onset of fever, chills, headache, nausea, vomiting, and rash develop. Symptoms become increasingly severe, and massive hemorrhage, multi-organ failure, and delirium may ensue. The case-fatality rate is between 23-90%. When diagnosing Marburg HF, malaria and typhoid fever are other infectious diseases that must be ruled out.
Treatment and prevention. The U.S. Food and Drug Administration has approved ERVEBO® (Ebola Zaire Vaccine, Live) for the prevention of disease caused by Zaire ebolavirus. But as with the other four species of ebola virus, an effective vaccine has yet to be developed for protection against Marburg virus. Researchers are, however, working on one. According to a February 15, 2023, article in the Journal of the American Medical Association, a chimpanzee adenovirus-vectored vaccine was recently found to be safe and immunogenic in a Phase 1 Clinical Trial. Until such a vaccine is developed, supportive hospital care is essential, and strict isolation procedures are required to restrict viral spread.
Geographic determinants of health. As is the case for many other infectious diseases, “location, location, location” is key.While outbreaks of infections caused by Marburg virus in Africa are alarming especially because the virus belongs to the same filovirus family as Ebola, at present those of us who live and work outside Africa need not be overly concerned. The African fruit bat Rosuettus aegyptiacus has not found its way to caves on other continents. But for public health workers and health care providers in afflicted areas of Africa, Marburg virus is a major concern, and the development of a safe and effective vaccine can’t happen soon enough.