Filovirus Surveillance in Communities Bordering Equatorial Guinea, Marburg Outbreak, Cameroon, 2023

Area of Science:

• Zoonotic disease surveillance
• Viral hemorrhagic fevers
• Epidemiology

Background:

• The 2023 Marburg virus (MARV) outbreak in Equatorial Guinea prompted investigations into potential regional spread.
• Filoviruses, including MARV and Ebola virus (EBOV), are known to cause severe, often fatal, hemorrhagic fevers.
• Bats are natural reservoirs for filoviruses, posing a risk for zoonotic spillover events.

Purpose of the Study:

• To assess the seroprevalence of MARV and EBOV antibodies in a human population in southern Cameroon following the Equatorial Guinea outbreak.
• To investigate the presence of MARV RNA in bats, a potential reservoir species, in the same region.
• To evaluate the need for enhanced surveillance of filovirus spillover risks in the region.

Main Methods:

• Cross-sectional serological survey of 181 individuals in southern Cameroon.
• Antibody detection using serological assays for MARV and EBOV.
• RNA testing for MARV in 289 captured bats, including 158 Rousettus aegyptiacus.

Main Results:

• MARV antibodies were detected in 3 individuals (1.65%) and EBOV antibodies in 7 individuals (3.87%).
• No MARV RNA was detected in any of the 289 bats tested.
• The presence of antibodies suggests past exposure to MARV or EBOV in the human population.

Conclusions:

• Despite the absence of detected MARV RNA in bats, the serological findings in humans indicate potential Marburg virus or Ebola virus circulation.
• Enhanced surveillance for filovirus spillover events in southern Cameroon and surrounding regions is crucial.
• Continued monitoring of both human and animal populations is necessary to understand and mitigate filovirus transmission risks.