Marburg Filoviridae virus infection (MFVI) is caused by one of the two virus genera in the Filoviridae family (the other is the Ebola virus). MFVI causes a hemorrhagic fever that has a high mortality rate, depending on the exact strain. Non-laboratory outbreaks of MFVI have occurred only in central Africa. Therefore, an outbreak of viral hemorrhagic fever in the United States should be highly suspect for a bioterrorism attack. (In January 2009, the US Centers for Disease Control and Prevention [CDC] confirmed the first known case of Marburg hemorrhagic fever in the United States. The patient had contracted the virus while visiting Uganda.) Although the primary method of transmission is thought to be through contact with infected bodily fluids or tissue, the most likely method of dispersal in a bioterrorism incident would be as an aerosol.

In 1967, the first identified cases of MFVI occurred in Marburg, Germany, among vaccine laboratory workers who came in contact with African green monkeys from Uganda. However, identification of the natural reservoir has been elusive, although non-human primates, rodents, and bats have all been suspected. Contact with the tissue of an infected animal has been implicated in some outbreaks. Person-to-person transmission has been documented and probably occurs through contact with bodily fluids, including those of the deceased or near-deceased when viral load is greatest.

After an incubation period of 2-14 days (usually 5-7 days), MFVI victims experience the sudden onset of high fever, chills, headache, extreme fatigue and weakness, myalgias, nausea, vomiting, abdominal pain, and diarrhea. A maculopapular rash (typically on the trunk) as well as pharyngitis, conjunctivitis, and/or a non-productive cough may occur. Five to seven days after onset, the disease may steadily progress to involve the well-known hemorrhagic manifestations (typically from the gastrointestinal [GI] tract, mucous membranes, eyes, urinary tract, nose, gums, and venipuncture sites). Other advanced symptoms include jaundice, pancreatitis, anorexia, photophobia, delirium, blindness, renal insufficiency, liver dysfunction, shock, and multi-system organ failure. Of note, in a 2023 case series of patients with Marburg virus disease in Equatorial Guinea, patients did not experience vomiting or diarrhea, and hemorrhagic signs appeared only at the terminal stage of the disease. The mortality rate of naturally occurring Marburg is approximately 25%-90%, with most deaths occurring within 2 weeks.

There is no human vaccine currently available, but some successful non-human primate trials suggest that human vaccine development may eventually have positive results.

Recent visitors to central Africa, zookeepers, owners of exotic pets, and veterinarians are susceptible to contracting MFVI.