Outbreak of Marburg Virus Disease, Equatorial Guinea, 2023

Abstract

In February 2023, the government of Equatorial Guinea declared an outbreak of Marburg virus disease. We describe the response structure and epidemiologic characteristics, including case-patient demographics, clinical manifestations, risk factors, and the serial interval and timing of symptom onset, treatment seeking, and recovery or death. We identified 16 laboratory-confirmed and 23 probable cases of Marburg virus disease in 5 districts and noted several unlinked chains of transmission and a case-fatality ratio of 90% (35/39 cases). Transmission was concentrated in family clusters and healthcare settings. The median serial interval was 18.5 days; most transmission occurred during late-stage disease. Rapid isolation of symptomatic case-patients is critical in preventing transmission and improving patient outcomes; community engagement and surveillance strengthening should be prioritized in emerging outbreaks. Further analysis of this outbreak and a One Health surveillance approach can help prevent and prepare for future potential spillover events.

Keywords: Equatorial Guinea; Marburg virus; Marburg virus disease; filoviruses; outbreak response; viral hemorrhagic fever; viruses; zoonoses.

Figure 1

Confirmed and probable cases of Marburg virus disease, Equatorial Guinea, December 2022–April 2023. A) Confirmed and probable cases of Marburg virus disease, by week of illness onset and case classification. Where date of symptom onset was unavailable (1 case), estimated date of sample collection was used. B–G) Confirmed and probable cases of Marburg virus disease (as in shown in panel A), by district: B) Nsok Nsomo; C) Ebibeyín; D) Bata; E) Evinayong; F) Nsork; G) Unknown. Gray shading indicates total number of cases in the country.

Figure 2

Confirmed and probable cases of Marburg virus disease, by district, Equatorial Guinea, January–April 2023.

Figure 3

Chain of transmission of Marburg virus disease cases, by date of symptom onset and district, Equatorial Guinea, December 2022–April 2023. Where date of symptom onset was unavailable (1 case), estimated date of sample collection was used. Cases are labeled by sex and age in years. Solid black lines indicate known contact links suspected to be associated with transmission events. A degree of uncertainty is associated with some links shown. In the context of epidemiologically linked clusters with numerous contact links, infector–infectee pairs could not be determined in some cases. Boxes around cases indicate groups of cases with known epidemiologic links (i.e., clusters).

Figure 4

Age group and sex distribution of persons with confirmed or probable Marburg virus disease, Equatorial Guinea, January–April 2023.