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 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. Infected fruit bats do not show 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 to date. 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%). The most recent outbreak began in Equatorial Guinea in January 2023.
Two outbreaks are currently under way in Equatorial Guinea and Tanzania, which are located on opposite sides of the African continent. Authorities in Equatorial Guinea have reported 15 confirmed cases, of which 11 were fatal. Three more probable cases have all been fatal. The cases have been spread across four different provinces without known connection, suggesting there has been undetected spread. The case-fatality rate among the confirmed cases has been 78.6%. Four of the lab-confirmed cases have involved healthcare workers, two of whom had died from their infections. Soon thereafter, another outbreak was reported in Tanzania involving eight cases. Five of them have been fatal and one death involved a healthcare worker. This is the first Marburg outbreak in each country, and genome sequencing is ongoing to determine whether the two outbreaks are related.
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
