First emergence of Marburg virus in Equatorial Guinea, 2023

On February 7th, 2023, an alert was given by the Ministry of Health in the district of Kie Ntem province, in eastern Equatorial Guinea. Several patients presented with symptoms suggestive of hemorrhagic fever, and a mortality cluster (n=9 deaths) was finally reported. An additional eight blood samples were collected from other contacts and sent to the regional WHO reference center for arboviruses and hemorrhagic fever viruses at the Institut Pasteur de Dakar (IPD), Senegal.
On February 12th, 2023, the samples were received by IPD team to carry out the molecular diagnostic targeting several hemorrhagic fever viruses. One of the blood samples was taken from a suspected case that was confirmed positive for Marburg virus (MARV). The diagnostic result was communicated to the stakeholders less than one day after sample reception.
An amplicon-based sequencing approach was undertaken using new designed MARV-specific primers and a close to complete whole genome was obtained with 98.1% coverage (compared to the reference genome NC_001608). A Maximum-Likelihood (ML) analysis showed that MARV in Equatorial Guinea 2023 mainly groups with the strains isolated from fruit bats Rousettus aegyptiacus in Sierra-Leone in 2017 (98.45% nt identity with isolate SLAB3960; genbank accession number: MN258361.1) and 2018 (97.41% nt identity with isolate 1000Kasbat; gb accession number: MN187403.1), as shown in figure 1.
This is the first report of MARV human infection in Equatorial Guinea. Previous reports of MARV in Guinea-Conakry and Ghana highlighted how a virus could spread over large distances through bat migration with an enzootic life cycle before a spillover event [1,2]. Some fruit bats such as R. aegyptiacus have already been identified as potential MARV reservoir hosts following previous serological or molecular studies [3,4].
Both epidemiology and phylogenetic history argue for a zoonotic transmission event from a reservoir, presumably a bat.
On March 23rd, 2023, eight new cases were reported from individuals from Kié-Ntem, Centre Sur and Litoral provinces with uncertain epidemiological links suggesting potential undetected community spread [5]. Moreover, Tanzania confirmed its first-ever MARV cases two days ago [6].
This work provide more information to decision makers for response management
and emphasize the needs for a large integrated (One Health) approach to MARV surveillance in view of recent detections made in the sub-Saharan region.

Figure 1.pdf (6.9 KB)

Figure 1. Phylogeny of MARV sequences. All available complete MARV sequences were downloaded from Genbank with Rvan virus. The sequence from Equatorial Guinea is colored in Red.

This work is part of the collaborations between several partners:

  • Amadou Alpha Sall, Institut Pasteur de Dakar, Dakar, Senegal (IPD)
  • Mitoha Ondo’o Ayekaba, Ministry of Health and Social Welfare (MHSW) in Equatorial Guinea
  • Ousmane Faye, IPD
  • George Ameh, World Health Organization (WHO)
  • Florentino Abaga Ndoho, MHSW in Equatorial Guinea
  • Abdourahmane Sow, IPD
  • Hieronyma Nelisiwe Gumede-Moeletsi, WHO
  • Xavier Berthet, IPD
  • Justino Obama, MHSW in Equatorial Guinea
  • Amadou Diallo, IPD
  • Safietou Sankhe, IPD
  • Elizabeth Lucas Nyakarungu, MHSW in Equatorial Guinea
  • Moussa Moise Diagne, IPD

We acknowledge the Africa CDC’s Africa Pathogen Genomics Initiative (Africa PGI) for support for equipment and reagents.

Genome sequence is available here.

The genome of Marburg virus from Equatorial Guinea is being shared pre-publication to support the public health response as well as the development and evaluation of Marburg virus disease diagnostics and therapeutics. The data may be used and analyzed for these purposes. A scientific publication is in preparation. If you intend to use these sequences prior to our publication, please communicate with His Excellency Mitoha Ondo’o Ayekaba, Minister of Health and Social Welfare in Equatorial Guinea, and Dr. Amadou Alpha Sall, CEO of Institut Pasteur de Dakar for coordination.


  1. Koundouno FR, Kafetzopoulou LE, Faye M, et al. Detection of Marburg Virus Disease in Guinea. N Engl J Med. 2022;386(26):2528-2530. doi:10.1056/NEJMc2120183.
  2. Bonney JHK, Sanders T, Adams P, et al. First-ever outbreak of Marburg virus disease declared in Ghana, 2022. (First-ever outbreak of Marburg virus disease declared in Ghana, 2022).
  3. Amman BR, Bird BH, Bakarr IA, et al. Isolation of Angola-like Marburg virus from Egyptian rousette bats from West Africa. Nat Commun 2020;11:510. 11.
  4. Olival KJ, Hayman DT. Filoviruses in bats: current knowledge and future directions. Viruses 2014;6:1759-88.
  5. World Health Organization (22 March 2023). Disease Outbreak News; Marburg virus disease - Equatorial Guinea. Available at: Marburg virus disease - Equatorial Guinea
  6. World Health Organization - AFRO (21 March 2023). Tanzania confirms first-ever outbreak of Marburg Virus Disease. Available at: