Marburg virus disease

Overview

Marburg Virus Disease (MVD), formerly known as Marburg haemorrhagic fever, is a rare but severe zoonotic disease. It is a rapidly progressive febrile illness that leads to haemorrhagic shock and death in a large proportion of cases.

Disease epidemiology

MVD was initially detected in 1967 when two simultaneous outbreaks occurred in Germany and Serbia, arising from laboratory researchers who were inadvertently exposed to the virus after performing necropsies on infected non-human primates that were imported from Africa for use in vaccine production. Since then, there have been several MVD outbreaks, all of which occurred in Central and East Africa, primarily in Uganda. The largest MVD outbreak to date involved more than 370 confirmed cases in Angola in 2004 and was centred on a paediatric ward where the infection apparently spread through contaminated transfusion equipment. There were also reports on sporadic cases of international travellers developing MVD after visiting caves colonised by fruit bats in Uganda.

In the first quarter of 2023, MVD outbreaks had been declared in Equatorial Guinea on 13 February, and in Tanzania on 21 March. Both outbreaks are geographically distinct, occurring on opposite sides of the African continent. The source of infection in both outbreaks is unknown – there were no known epidemiological links between the two outbreaks. As of 2 and 8 June 2023, the outbreaks were declared over in Tanzania and Equatorial Guinea respectively. The case fatality ratios (CFR) have varied from 23% to 90% in past MVD outbreaks. Another outbreak was confirmed in Rwanda on 27 September 2024 and was declared over by WHO on 20 December 2024. A total of 66 confirmed cases and 15 deaths were recorded.

On 14 January 2025, the WHO reported a suspected outbreak of MVD in the Kagera region of Tanzania. Following investigations, on 20 January 2025, the outbreak was confirmed, making it the latest MVD outbreak. As of 31 January 2025, two confirmed cases and eight probable cases had been reported.

Pathogen(s)

Marburg virus (MARV) and Ravn virus (RAVV) of the species Orthomarburgvirus marburgense are the causative agents of Marburg virus disease (MVD). Both viruses are part of the Filoviridae family (filovirus) to which Orthoebolavirus genus belongs. Though caused by different viruses, Ebola and Marburg diseases are clinically similar.

Egyptian fruit bats (Rousettus aegyptiacus) native to Africa are considered the natural hosts.

Transmission

Transmission can occur through direct contact with body fluids of infected persons or animals, or indirectly via contaminated surfaces and materials.

Animal-to-human transmission of the virus occurs through close contact with contaminated tissues and bodily fluids of infected animals. This may occur during prolonged exposure to mines or caves inhabited by Rousettus bat colonies. Other animal-to-human transmission may occur from contact or consumption of tissue and bodily fluids from infected Non-Human-Primates (NHPs) without appropriate protective equipment or thorough cooking.

Human-to-human transmission can occur through direct contact with blood, bodily fluids, or secretions from an infected person through non-intact skin, mucosa, percutaneous injury, or sexual intercourse. Contact with infected corpses or environments that have been contaminated with an MVD patient’s bodily fluids may also spread the infection.

Incubation period: Typically 5 to 10 days; range is 2 to 21 days.

Infectious period: Infected individuals are not contagious during the incubation period and become infectious once they begin to develop symptoms, and remain infectious as long as their blood and body fluids contain the virus. Marburg Virus may also be transmitted through semen after recovery from MVD. There is no evidence that Marburg virus can spread through sex or other contact with vaginal fluids from a woman who has recovered from MVD.

Clinical features

Presentation of MVD is similar to the Ebola Virus Disease. Early symptoms such as fever, headache, sore throat, myalgia, joint pain, and malaise can be varied and non-specific. Progression to maculopapular rash, abdominal pain, nausea, vomiting, diarrhoea, gum bleeding and gastrointestinal bleeding should alert the clinician to MVD. In the late phase of the disease, patients may experience orchitis and central nervous system (CNS) manifestations of confusion, agitation, seizures or coma.

Risk factors

Risk factors include exposure to:

• African fruit bats, or their saliva, urine or excretions

• Infected non-human primates, including handling of bush meat

• Blood and body fluids from infected persons, or contaminated environment and materials

Diagnosis

Diagnosis in acute infection is by detection of MARV by polymerase chain reaction (PCR) in blood specimens. Diagnostic tests for MVD should be performed only after discussion with MOH. All blood samples taken from inpatients are to be sent to the National Public Health Laboratory (NPHL) for MVD testing through the laboratory. NPHL will provide laboratory support and guidelines for testing, including protocols for specimen transport, testing and reporting.

Treatment and management

To date, there are no approved vaccines or antiviral treatments for MVD. Vaccines and treatments developed against Ebola virus disease are ineffective against MVD. The World Health Organization (WHO) is prepared to support trials of four Marburg vaccines in Equatorial Guinea and Tanzania.

In the absence of proven antivirals, supportive care remains the mainstay of treatment for MVD. This includes:

• Diagnosis and treatment of concomitant infections such as malaria or bacteremia

• Active management of fluids and electrolytes

• Managing nausea and vomiting

• Supplemental oxygen (if needed)

• Inotropic support (if needed)

• Analgesics (if needed)

• Blood product support if haemorrhage occurs

• Support for multi-organ dysfunction, e.g., renal replacement therapy (if needed)

Precaution, prevention, and control

General advice

All suspect cases of MVD should be isolated immediately to limit contact with other persons while awaiting risk assessment, conveyance and admission. Strict contact and airborne precautions should be exercised. Staff are reminded to practice good hand hygiene at all times.

For a suspect case with:

• Low index of suspicion for MVD, the patient will be admitted and isolated in an airborne infection isolation room2 (AIIR) in isolation wards in the respective acute care hospital. This includes suspect cases presenting at emergency department or specialised outpatient clinics.

• High index of suspicion for MVD or confirmed to have MVD, arrangements will be made to transfer the patient using a trained ambulance operator to NCID to be managed at the high-level isolation unit.

All cases with a high index of suspicion of MVD should be isolated in Airborne Infection Isolation Room (AIIR) at a minimum and placed on strict contact and airborne isolation precautions.

Only essential personnel trained in donning/doffing of appropriate PPE should attend to a suspect or confirmed MVD case or their body fluids. All personnel attending to individuals with:

• High index of suspicion for MVD or confirmed to have MVD should don PPE comprising:

  • Disposable fluid-resistant hood to cover the head and neck areas (staff with long hair may wish to use head cover prior to wearing hood)

  • Eye protection gear (e.g., disposable downward face shields secured at forehead or goggles)

  • Fluid-repellent N95 mask

  • Inner and outer disposable fluid-resistant (AAMI 4) gown (should extend at least until the ankle portion of the boot cover)

  • 12-inch double nitrile or latex gloves certified for healthcare use (extended cuffs should reach up to mid forearm)

  • Disposable fluid resistant boot covers (should extend up to knee-height)

• Low index of suspicion for MVD should minimally don PPE comprising:

  • Fluid-repellent N95 mask

  • Eye protection gear (e.g., disposable downward face shields secured at forehead or goggles)

  • Disposable fluid-resistant (AAMI 4) gown

  • 12-inch nitril or latex gloves certified for healthcare use

Staff attending to suspect MVD case should be closely monitored (e.g. twice daily temperature monitoring), even if they wear the appropriate PPE. Unprotected exposure should be reported to MOH immediately. A log of all staff attending to the patient should be maintained.

Persons with skin or mucousal exposure to body fluids from a suspect MVD case should immediately wash the affected skin surfaces with soap and water. Mucous membranes (e.g. conjunctiva) should be irrigated with copious amounts of water or eyewash solution.

Notification

MVD is an emerging infectious disease and is legally notifiable in Singapore. All suspected cases of MVD should be reported to MOH immediately and instructions will be provided on further management of these cases. MOH will arrange for transfer of suspected cases to the NCID on a case-by-case basis. All confirmed MVD cases will be managed at the HLIU in NCID.

Who should notify:

• Medical Practitioners

• Laboratories

When to notify:

• On clinical suspicion

Suspect case definition:

• Fever (>38°C) or current history of fever

• Onset of symptoms within 21 days of:

  • Travel history to any area or region with confirmed case(s) of MVD [refer to World Health Organization (WHO)]

  • Close contact to a confirmed or suspect case of MVD

• On laboratory confirmation of positive PCR

How to notify:

• Please refer to the Infectious Disease Notification for more information.

Notification timeline:

• Immediately

Resources

Get MVD situation updates from WHO.