Marburg virus disease

Situation at a glance

On 8 June 2023, after two consecutive incubation periods (42 days) without a new confirmed case reported, the Ministry of Health of Equatorial Guinea declared the end of the Marburg virus disease (MVD) outbreak, as per the WHO recommendations. A total of 17 confirmed and 23 probable cases were reported from five districts in four provinces; 12 of the 17 confirmed cases died and all of the probable cases were reported deaths.

WHO and partners provided technical support to the government to contain this outbreak through its country office.

WHO encourages maintaining most response activities for three months after the outbreak ends. This is to make sure that if the disease re-emerges, health authorities are able to detect it immediately, prevent the disease from spreading again, and ultimately save lives.

Description of the situation

On 13 February 2023, the Ministry of Health and Social Welfare of Equatorial Guinea declared an outbreak of MVD after suspected viral hemorrhagic fever deaths were reported between 7 January and 7 February 2023, and a case tested positive on 12 February for Marburg virus by real-time polymerase chain reaction (RT-PCR) at the Institut Pasteur de Dakar in Senegal.

From the outbreak declaration until 7 June 2023, 17 confirmed and 23 probable cases were reported in the continental region of Equatorial Guinea. Twelve of the confirmed cases died and all of the probable cases were reported deaths (the case fatality ratio among confirmed cases is 75%, excluding one confirmed case with an unknown outcome).

The last confirmed case admitted to a Marburg treatment center in Bata district in Litoral province was discharged on 26 April, after two consecutive negative PCR tests for MVD. On 8 June 2023, after two consecutive incubation periods (42 days) without a new confirmed case reported, the Ministry of Health of Equatorial Guinea declared the end of the outbreak.

Confirmed or probable cases were reported in five districts (Bata, Ebebiyin, Evinayong, Nsok Nsomo and Nsork) in four of the country's eight provinces (Centro Sur, Kié-Ntem, Litoral and Wele-Nzas).

Five cases (31%) were identified among healthcare workers, of whom two died (CFR among HCWs: 40%).

Four patients recovered and were enrolled in a survivor care programme to receive psychosocial and other post-recovery support.

Figure 1. MVD cases by week of symptoms onset* and case classification, Equatorial Guinea, as of 7 June 2023.

Figure 2. Map of districts reporting MVD confirmed and probable cases during the outbreak, Equatorial Guinea.

Epidemiology of Marburg virus disease

Marburg 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. Burial ceremonies that involve direct contact with the body of the deceased can also contribute to the transmission of Marburg virus.

The incubation period varies from two to 21 days. Illness caused by Marburg virus begins abruptly, with high fever, severe headache, and severe malaise. Severe haemorrhagic manifestations may appear between five and seven days from symptom onset, although not all cases have haemorrhagic signs, and fatal cases usually have some form of bleeding, often from multiple areas.

Although no vaccines or antiviral treatments are approved to treat the virus, Remdesivir was used in this outbreak on compassionate care basis. Supportive care – rehydration with oral or intravenous fluids – and treatment of specific symptoms improve survival. A range of potential treatments are being evaluated, including blood products, immune therapies, and drug therapies.

This was the first documented outbreak of MVD reported in Equatorial Guinea. Another MVD outbreak was recently declared over in the United Republic of Tanzania (for more information, see the Disease Outbreak News published on 2 June 2023). MVD outbreaks have been previously reported in Ghana (2022), Guinea (2021), Uganda (2017, 2014, 2012, 2007), Angola (2004-2005), the Democratic Republic of the Congo (1998 and 2000), Kenya (1990, 1987, 1980) and South Africa (1975).

Coordination

Partner Support

Surveillance

Laboratory

Clinical care

Infection Prevention and Control (IPC) and WASH (Water, Sanitation and Hygiene)

Risk Communication and Community Engagement (RCCE)

Border health and points of entry

Operational support and logistics (OSL)

Readiness and preparedness in neighboring countries

In compliance with WHO recommendations, the criteria to declare the end of an outbreak after two maximum incubation periods (42 days) was observed with no new confirmed or probable case of MVD detected.

Based on knowledge of past outbreaks of filovirus disease, there remains a risk of re-emergence of MVD even following the declaration of the end of the outbreak. Undetected transmission of Marburg virus may exist in the country; not all chains of transmission were definitively linked, and one confirmed case was never identified. The initial source of the outbreak has not been identified, and a new emergence of disease is possible, including from interaction with animal reservoirs. The virus may also persist for an extended period in body fluids of survivors, including semen, underlying the importance of their participation in the survivors program, and the support the program provides.

Based on the available information at the end of MVD outbreak in Equatorial Guinea, the risk of MVD remerging is considered as low at the national level, low at the subregional level, regional level and at the global level.

The current WHO recommendation is that most response activities continue for three months after the outbreak ends, to make sure that if the disease re-emerges, health authorities can detect it right away, prevent the disease from spreading, and ultimately save lives.

WHO advises the following risk reduction measures as an effective way to reduce MVD transmission:

WHO advises against applying international travel and/or trade measures to Equatorial Guinea.

Citable reference: World Health Organization (9 June 2023). Disease Outbreak News; Marburg virus disease - Equatorial Guinea. Available at https://www.who.int/emergencies/disease-outbreak-news/item/2023-DON472