Marburg fever, formerly known as Marburg haemorrhagic fever, is a frequently fatal viral disease caused by the Marburg virus(Marburg marburgvirus, MARV). This virus belongs to the Filoviridae family, which also includes the Ebola virus. The Nile flying fox is considered the natural host of MARV. The pathogen is initially transmitted to humans by fruit bats or intermediate hosts and can subsequently spread further through human-to-human transmission.

MARV was first described in 1967 during two simultaneous outbreaks in laboratories in Marburg (Germany) and Belgrade (former Yugoslavia), where laboratory staff worked with tissue from African green monkeys(Cercopithecus aethiops) imported from Uganda that were infected with MARV. Later, in addition to two major outbreaks in the Democratic Republic of Congo (1998-2000) and Angola (2005), there were several smaller local outbreaks in Kenya (1980, 1987), Uganda (2007, 2012, 2014, 2017, 2022), Guinea (2021), Ghana (2022), Equatorial Guinea (2023) and Tanzania (2023). There have been imported cases in South Africa (1975, imported case from Zimbabwe), the Netherlands and the USA (2008, imported cases from Uganda). There has been an outbreak in Rwanda since September 2024.

The natural host and reservoir of MARV is the Nile flying fox(Rousettus aegyptiacus), a bat species that is mainly found in the dry forests of equatorial Africa. The distribution area of the Marburg virus therefore largely coincides with that of the Nile flying fox. Other animal species, such as certain monkey and antelope species, can also serve as intermediate hosts for MARV (and therefore also play a role in the infection process).

Most natural MVD outbreaks are due to human intrusion into mines and caves inhabited by bats. Transmission occurs through direct contact with infectious blood, secretions, organs or semen (human-to-human) or through contact with infected animals (including consumption of reservoir animals or intermediate hosts - "bushmeat").Infection often occurs during the care and treatment of sick persons through direct contact or with objects contaminated by the body fluids of sick persons and at funeral ceremonies where there is direct contact with the body of deceased persons.

During the incubation period, the virus cannot yet be transmitted; infected persons only become infectious when the first symptoms appear and remain so for the entire duration of their viraemia.

The initial symptoms resemble a flu-like infection with a sudden high temperature (typically 39-40 °C), muscle pain, weakness, headache and sore throat as well as a poor general condition. This is followed by vomiting, diarrhoea and maculopapular (blotchy, nodular) skin rashes. Severe haemorrhagic disease can lead to heavy bleeding, failure of vital organs such as the liver and kidneys, or shock. The average mortality rate is 50%, ranging from 24% to 88% according to observations of past outbreaks.

There is currently no specific antiviral treatment.

A vaccine is being developed but has not yet been authorised.

The consistent use of PPE (personal protective equipment) by staff involved in the treatment of patients is essential; the same applies to protective measures in high-risk workplaces such as mines and caves. Gloves and other appropriate protective clothing (including masks) should be worn and close physical contact with MARV patients should be avoided. Patients suspected or confirmed to have MARV should be consistently isolated to allow early treatment and prevent transmission at home. To contain an outbreak, consistent contact tracing and follow-up for 21 days is critical; if symptoms occur, patients must be consistently isolated.

No cases of Marburg virus have yet been reported in Austria.