What are the causes?
Marburg virus disease is caused by a single-strand RNA virus belonging to the Filoviridae family. The virus is filamentous and variable in size, with viral particles measuring 800nm long and 80nm in diameter on average. Marburg virus shares several characteristics with Ebola virus, and like Ebola it can cause hemorrhagic fever in humans.
How does the virus spread?
The natural reservoir of Marburg virus is the Egyptian rousette bat (Rousettus aegyptiacus), a migratory fruit bat found in sub-Saharan Africa and the Nile Valley.
Marburg virus is transmitted to humans if they come into lengthy contact with infected bats, usually in caves or mines. The virus can then spread from one person to another following direct contact with the blood or bodily fluids of infected individuals. Sexual transmission can also occur via semen, as the virus can persist for several months in the testicles. Marburg virus can also spread via contaminated objects such as beds or syringes.
Strict preventive measures should be taken by healthcare workers to prevent the virus from circulating. Funeral rites and burial ceremonies involving direct contact with the body of the deceased may contribute to the spread of the disease.
What are the symptoms?
The first symptoms of infection with Marburg virus can appear between 4 and 21 days after exposure, with an average incubation period of 5 to 9 days.
Patients initially develop high fever, severe headache and muscle pain, followed by gastrointestinal symptoms such as vomiting and diarrhea. Around day five of the disease, a rash and spontaneous bleeding from the nose, gums, etc. are frequent.
The central nervous system may be affected, resulting in aggression, confusion and delirium.
The disease may lead to shock and multiple organ failure. Death, often preceded by significant blood loss, generally occurs between eight and nine days after the onset of symptoms.
How is Marburg virus disease diagnosed?
Diagnosis is established by laboratory testing, including:
- RT-PCR, used to detect viral genetic material during the acute phase of the disease;
- IgM and IgG serological testing to reveal antibodies to the virus, generally used for late or retrospective diagnosis.
Biological samples can only be handled in maximum containment laboratories because of the high risk of infection and the extreme pathogenicity of the virus. Rapid diagnosis is crucial to isolate infected individuals, treat anyone they have come into contact with and implement outbreak control measures.
What treatments are available?
There is currently no specific vaccine or antiviral treatment for Marburg virus disease.
Patients are given supportive care to treat specific symptoms. Rehydration, treatment of secondary infections and oxygen therapy improve the chances of survival, but in many cases patients do not survive.
There is currently no specific treatment or vaccine for the virus. Experimental vaccines have proven effective in animals but have yet to be validated in humans.
Monoclonal antibodies are being developed. Antiretroviral drugs have been used in clinical trials on Ebola virus disease and could be tested for Marburg virus disease.
How can Marburg virus disease be prevented?
There is no preventive vaccine.
Prevention involves avoiding contact with fruit bats and their resting places, such as caves and mines in affected regions. In the event of an outbreak, strict isolation measures for infected individuals, protection for healthcare workers, contact tracing and disinfection of surfaces and objects are crucial. Burial rites must be supervised to prevent people from touching infected bodies.
Who is affected?
Since the virus was identified in 1967, a small number of outbreaks and sporadic cases have been reported. The main outbreaks have occurred:
- in the Democratic Republic of the Congo in 1998-2000: 128 deaths from 154 cases
- in Angola in 2005: 329 deaths from 374 cases
More recently, outbreaks have emerged in Rwanda and Tanzania.
The geographical distribution of the virus is likely to correspond to regions where Egyptian rousette bats, the natural host of the virus, are found.
For more information, see:
- the fact sheet from the European Centre for Disease Prevention and Control