Marburg Virus

Marburg is an enveloped single-stranded RNA filovirus, that belongs to the same family as Ebola viruses and causes severe hemorrhagic fever. Marburg virus is named after the city of Marburg in Germany. Approximately 600 infected green monkeys (Chlorocebus aethiops) were shipped to Marburg, Frankfurt, and Belgrade in 1967. Laboratory workers in Marburg and Frankfurt apparently became infected after working with kidney cell cultures derived from infected monkeys. In Belgrade, a veterinarian became infected while performing an autopsy on a deceased monkey. Altogether, 32 people became infected and 7 died.

Marburg virus has a broad distribution range throughout Sub-Saharan Africa. The likely primary natural reservoir is the Egyptian fruit bat (Rousettus aegyptiacus) that lives in caves. Fruit bats harboring the virus do not exhibit any obvious signs of illness. 

Marburg virus can spill over from bats to old world monkeys, non-human primates (chimpanzees and gorillas) and humans. It is not known how Marburg virus spreads from bats to people but contact with bat feces or aerosols is most likely. Marburg virus spreads among people through contact with the blood or body fluids of infected patients. 

Approximately 20 outbreaks of Marburg virus have been recorded since 1975. Most Marburg outbreaks have been small, but a large outbreak occurred in Angola in 2004 to 2005 that resulted in 374 cases and 329 deaths (case fatality rate of 88%). 

In 2023, two outbreaks occurred in Equatorial Guinea and Tanzania, which are located on opposite sides of the African continent. On February 13, the Government of Equatorial Guinea declared a Marburg disease outbreak. There were 16 confirmed cases, of which 12 were fatal. An additional 23 probable cases were also reported, all of whom died. The WHO declared the outbreak over on June 8, 2023.

On March 21, 2023, Tanzania’s government declared the country’s first outbreak of Marburg disease. There were 8 confirmed cases, of which 5 died. In September 2024, Rwanda’s health ministry reported the country’s first Marburg virus outbreak. So far, 26 people had become ill and 8 of them had died. Most of the patients were healthcare workers, especially those working in intensive care units. 

Following an incubation period of 2 to 21 days, patients infected with Marburg virus suddenly develop fever, chills, headache, and myalgia. A maculopapular rash may appear around the fifth day after symptom onset. Patients also may develop nausea, vomiting, diarrhea, abdominal pain, and sore throat. As the disease progresses, patients develop pancreatitis, liver failure, massive hemorrhaging, and eventually multi-organ failure. The case fatality rate has ranged from 23 to 90%. Unlike Ebola, there are no specific antiviral drugs or vaccines for Marburg virus disease.

Clinical diagnosis of Marburg virus disease is difficult because the signs and symptoms resemble other infectious diseases such as malaria, typhoid fever, dengue fever, Lassa fever or Ebola. The diagnosis can be confirmed by laboratory testing. Antigen-capture enzyme-linked immunosorbent assay (ELISA) testing, polymerase chain reaction (PCR), and IgM-capture ELISA can be used to confirm a case of Marburg virus disease within a few days of symptom onset. IgG-capture ELISA is useful to confirm infections later in the course of disease or after recovery. Virus isolation is possible but should only be done in a high containment laboratory with good laboratory practices. 

References

Schnirring L. Equatorial Guinea confirms its first Marburg fever outbreak. CIDRAP, February 13, 2023.

Centers for Disease Control and Prevention, Marburg Virus Disease, https://www.cdc.gov/vhf/marburg/index.html

Professor Francois Balloux, A few facts about Marburg virus, Twitter, March 26, 2023. 

Schnirring L. Rwanda reports first Marburg virus outbreak. CIDRAP, September 30, 2024