Situation at a glance
Since the last Disease Outbreak News on this event was published on 22 March 2023 (with data as of 21 March 2023), six additional laboratory-confirmed cases of Marburg virus disease (MVD) have been reported in Equatorial Guinea. This brings the total to 15 laboratory-confirmed and 23 probable cases since the declaration of the outbreak on 13 February 2023. Among the laboratory confirmed there are 11 deaths (Case Fatality Ratio 78.6%; for one confirmed case the outcome is unknown), and all probable cases are dead. The most affected district is Bata in Litoral province, with nine laboratory-confirmed MVD cases reported.
WHO is supporting the Ministry of Health by strengthening different response pillars, including but not limited to surveillance, including at points of entry; laboratory; case management; infection prevention and control; risk communication and community engagement.
MVD is a disease with high mortality that causes haemorrhagic fever, and is among the diseases that require assessment under the International Health Regulations.
On 30 March 2023, WHO assessed the public health risk posed by this outbreak as very high at the national level, high at sub-regional level, moderate at the regional level and low at the global level.
WHO advises against restrictions to international travel and/or trade in Equatorial Guinea.
Description of the situation
On 13 February 2023, the Ministry of Health and Social Welfare of Equatorial Guinea declared an outbreak of Marburg virus disease (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 Institute Pasteur in Dakar, Senegal.
Since the last Disease Outbreak News on this event (22 March 2023) and as of 11 April 2023, six additional laboratory-confirmed cases of MVD were reported in Equatorial Guinea, bringing the total of cases in the outbreak to 15 laboratory-confirmed. Additionally, 23 probable cases have been reported since the start of the outbreak. Eleven deaths were recorded among laboratory-confirmed cases (Case Fatality Ratio (CFR) among confirmed cases 78.6%), and all probable cases are dead; for one confirmed case the outcome is unknown. Four laboratory-confirmed cases (26.6%) were reported among healthcare workers, of whom two died. Among the confirmed cases, three have recovered.
Figure 1. MVD cases by week of onset* and case classification, Equatorial Guinea, as of 11 April 2023. 
Among MVD laboratory-confirmed cases with age and sex information (n = 13), the majority occurred among females (9/14; 64.3%), while the most affected age group is 40-49 years (6/14; 42.8%), followed by the age groups 10-19 and 30-39 (three cases each).
Five districts (Bata, Ebebiyin, Evinayong, Nsok Nsomo and Nsork) in four provinces (Centro Sur, Kie Ntem, Litoral and Wele-Nzas) have been affected by the outbreak (Figure 2), with Bata district reporting the majority of confirmed cases (n = 9) and deaths (n = 6), and Ebebiyin district, where the outbreak was first detected, reporting the majority of probable cases,(n = 11) (Table 1).
In the last 21 days (from 22 March 2023 to 11 April 2023), five confirmed cases were reported from Bata (n = 4) and Nsork (n = 1) districts (Figure 3). Among the four cases reported from Bata district, three cases have an epidemiological link either through a family cluster or through health care setting. The fourth and most recent case was reported on 7 April; an investigation of this case is ongoing to establish transmission chains and ensure appropriate identification of all contacts.
Since the last Disease Outbreak News on this event, one new district, Nsork in Wele-Nzas province, has been affected by the outbreak, reporting one confirmed case, linked to a known case from another district that previously reported confirmed cases.
Since the start of the outbreak and as of 10 April 2023, a total of 1322 contacts have been listed, with an average follow-up rate around 80-90%.
Table 1. Number of MVD cases and deaths, by district and case classification, Equatorial Guinea, as of 11 April 2023. 
Figure 2. Map of districts reporting MVD confirmed and probable cases as of 11 April, Equatorial Guinea. 
Figure 3. Map of districts reporting MVD confirmed cases in the last 21 days (from 21 March 2023 to 11 April 2023), 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, clothing contaminated with these fluids. Healthcare workers have previously been infected while treating patients with suspected or confirmed MVD. 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 is being used on compassionate care bases. 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 is the first time that Equatorial Guinea has reported an outbreak of MVD. Another MVD outbreak is currently taking place in Tanzania with a total of eight confirmed cases and five deaths as of 4 April 2023. Other 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).
Equatorial Guinea is facing an outbreak of MVD for the first time and the country’s capacity to manage the outbreak needs to be strengthened. In addition to the nine confirmed cases reported in the Disease Outbreak News of 22 March, six more individuals have tested positive for MVD, with an additional affected province. While many cases are linked within a social network or by geographic proximity, the presence of cases and/or clusters across multiple districts without clear epidemiologic links may indicate undetected transmission of the virus. The presence of confirmed cases in Bata increases the risk of disease spread, as it is the most populated city and economic hub of Equatorial Guinea, with an international airport and port. Bata has also reported the highest number of confirmed cases and confirmed deaths. The last case was also reported from Bata and investigation is ongoing to establish transmission chains. The country surveillance system remains suboptimal with few alerts reported and investigated. Several epidemiological links and transmission chains have not been detected, thus there might be contacts not identified.
Implemented infection prevention and control measures are insufficient as demonstrated by MVD cases reported among healthcare workers. The diagnostic capacity for Marburg virus in the country is limited in terms of the number of samples that can be analyzed per day (a maximum of around 50 a day). The community’s perception of risk is estimated to be very low. There are frequent population movements between the different districts of the mainland region, as well as with the island region, despite the quarantine measures implemented in several of the affected areas. Frequent population movements and very porous land borders are also reported in the districts bordering Cameroon and Gabon, with surveillance at land entry points being suboptimal, and countless uncontrolled paths or trails along the border with Cameroon and Gabon. Also, surveillance at the entry points of the international Bata airport or international seaport, is not optimal.
Considering the above-described situation, on 30 March 2023, WHO assessed the risk posed by this outbreak as very high at the national level, high at sub-regional level, moderate at the regional level and low at the global level.
Marburg virus disease outbreak control relies on using a range of interventions, such as prompt isolation and case management; surveillance including active case search, case investigation and contact tracing; an optimal laboratory service; infection prevention and control, including prompt safe and dignified burial; and social mobilization. Community engagement is key to successfully controlling Marburg disease outbreaks. Raising awareness of risk factors for infection with Marburg virus and the protective measures that individuals can take is an effective way to reduce human transmission. Health and care workers caring for patients with confirmed or suspected MVD should apply IPC measures including standard and transmission-based precautions to avoid contact with the patient’s blood and body fluids and with contaminated surfaces and objects. Health facilities should ensure environmental controls, such as adequate water, sanitation and hygiene, as well as that safe infectious waste management protocols are in place to enable health workers to practice IPC measures. WHO recommends that male survivors of MVD practice safer sex for 12 months from onset of symptoms, or until their semen twice tests negative for the Marburg virus. Contact with body fluids should be avoided and washing with soap and water is recommended. WHO does not recommend isolation of male or female convalescent patients whose blood has tested negative for the Marburg virus.
Based on the available information and current risk assessment, WHO advises to strengthen surveillance at points of entry in the affected areas in Equatorial Guinea for the identification of cases, including through exit screening; to map cross-border population mobility to identify populations in vulnerable situations and target public health interventions; and to provide public health information and advice in all relevant languages at points of entry and in adjacent communities near land borders. In addition, suspect, probable and confirmed cases and their contacts should not undertake travel, including international.
WHO advises against any other international travel and/or trade measures in Equatorial Guinea.
States Parties adopting international travel- and trade-related measures potentially more restrictive than those advised by WHO, are invited to report them to WHO, pursuant to Article 43 of the International Health Regulations (2005).
