Marburg virus is a rare but severe hemorrhagic fever that affects both people and non-human primates. It is caused by the Marburg virus, a genetically unique zoonotic RNA virus of the filovirus family. The virus spreads between people via direct contact through broken skin or mucous membranes with the blood, secretions, organs, or other bodily fluids of infected people, and with surfaces and materials such as bedding and clothing contaminated with these fluids. Healthcare workers have previously been infected while treating suspected or confirmed MVD patients. Symptoms of Marburg virus disease begin abruptly, with high fever, severe headache, and severe malaise. Severe hemorrhagic manifestations may appear between five and seven days from symptom onset, although not all cases have hemorrhagic signs, and fatal cases usually have some form of bleeding, often from multiple areas.

The first-ever Marburg virus disease outbreak in Equatorial Guinea was confirmed in February 2023. As of 4 April 2023, there were 14 confirmed cases and 28 suspected cases, including ten confirmed deaths from the disease in Equatorial Guinea. On 8 June 2023, the World Health Organization declared the outbreak over. In total, 17 laboratory-confirmed cases and 12 deaths were recorded. All the 23 probable cases reportedly died. Four patients recovered from the virus and have been enrolled in a survivors program to receive psychosocial and other post-recovery support.

Marburg virus has been most frequently found in Uganda and Kenya around Lake Victoria. The fatality rate in previous outbreaks has averaged close to 80%. The largest Marburg virus outbreak occurred in 2004 and 2005 in Angola, resulting in 374 cases. In late March 2023, a new outbreak of Marburg virus disease was reported in the northwest corner of Tanzania, on the shores of Lake Victoria. There have been nine reported cases to date.