Between January 7th and February 6th, 2023, the Ministry of Health of Equatorial Guinea identified a cluster of deaths in two remote districts of the continental region of Equatorial Guinea (Nosrk Nsomo and Ebebiyim) where a total of nine deaths occurred with similar symptoms related to viral hemorrhagic fever. Equatorial Guinea currently does not have laboratory capacity to test for VHF, hence samples from those who were sick and from close contacts were sent to Gabon and Senegal. The samples sent for testing in Gabon were negative, but out of the eight samples sent to Dakar, Senegal, one tested positive for Marburg virus. On February 13, 2023, the Equatorial Guinea MoH officially declared the outbreak.

As of February 17, there is one confirmed case, eight probable cases, and 16 suspect cases in isolation. Of the 16 suspect cases, two are showing signs and symptoms. In addition, 21 individuals are considered secondary contacts and are in isolation at home. There is restricted access to Kie Ntem district, with an estimated 4,235 people in quarantine. The affected district is located in the north-east of Equatorial Guinea mainland, bordering Cameroon and Gabon. Several suspected cases were identified in Cameroon, but all samples were negative for Marburg virus. There is no notification of cases or symptoms related to Marburg on the Gabonese territory.

Marburg Virus Disease (MVM) is a highly virulent disease that causes haemorrhagic fever, with a case fatality rate of up to 88%. It belongs to the same family of viruses that cause Ebola virus disease. The disease caused by the Marburg virus begins abruptly, with a high fever, severe headache, and severe malaise. Many patients develop severe haemorrhagic symptoms within seven days. The virus is transmitted to humans by fruit bats and spreads among humans through direct contact with the body fluids of infected people, surfaces, and materials. There is no approved vaccine or antiviral treatment for the virus. However, supportive care - rehydration with oral or intravenous fluids - and treatment of specific symptoms improves survival.

The Marburg outbreak declared on February 13, 2023, is the first VHF outbreak in Equatorial Guinea. The attack rate is high, at 23% for relatives and 81% for those providing direct care to infected persons when precautions are not strictly practiced. Moreover, case fatality ratios from past outbreaks have ranged from 24% to 88%, depending on the case management. The above, associated with the time elapsed between the identification of the first symptoms (7 January) and the confirmation of the virus (13 February), considerably heightens the potential of widespread infection and poses challenges to the response and overall control of a very virulent outbreak.

According to government information, initial alerts and deaths have been traced back to public events which, according to local religious and cultural customs, bring together several dozen and sometimes hundreds of people. Untraced contacts in the community, rumors, and lack of information within the communities could be an important transmission lever that needs to be managed urgently.

Given the low levels of contact tracing, the reduced number of samples collected, the lack of testing capacity in-country, the time required to collect and send samples to other countries, and the delays in obtaining results, the current numbers may not entirely reflect the reality of the outbreak. It is crucial to respond urgently to this outbreak to prevent further spread of the disease.