Ebola Virus Circulation in a Non-Epidemic Guinean Rural Area: Virological and Anthropological Approaches

Abstract

Background: The recurring resurgence of Ebola virus disease causes deaths, fosters the loss of confidence in the healthcare system, and has a tremendous socio-economic impact on already fragile societies. Scientific research to trace the circulation of the virus is crucial to monitor the evolution of the epidemic and design effective prevention and control strategies in high-risk countries. This study analyzes the seroprevalence of orthoebolaviruses in a rural population in Madina Oula (Guinea), based on a 1987 outbreak and socio-historical data.

Methods: A cross-sectional study conducted from March 14 to April 3, 2022, in Madina Oula involved recording household and socio-demographic characteristics, lifestyle data, and collecting dried blood spots (DBS) from 878 individuals in 236 households. DBS were tested using multiplex serology to detect antibodies to different orthoebolaviruses (Ebola (EBOV), Bundibugyo (BDBV), Sudan (SUDV), Reston (RESTV) and Bombali (BOMV)). Seroprevalence was estimated with a 95% CI, and household, socio-demographic and lifestyle characteristics were described using median (IQR), absolute and relative frequencies. The results were discussed with collective memories of the outbreak and socio-historical conditions since 2016.

Findings: Between 1982-1983, an outbreak of heamorraghic fever reported 137 deaths, and it was estimated that 20% of the population had been exposed to Lassa or Ebola virus. Serological analysis showed varied reactivity to orthoebolavirus antigens, the highest reactivity was observed with GP antigens, especially for glycoprotein SUDV (16%). 21 samples on 878 were reactive with at least two antigens of the same virus species, their median age was 27 (IQR = 10·00 - 35·00) years and varies from 2 to 80 years. Presence of antibodies varied per village, highest in Ouassou and Dar-es-Salam

Interpretation: In an area unaffected by recent Ebola outbreaks, serological data showed traces of orthoebolavirus circulation, suggesting possible endemicity. This highlights the importance of preparedness for known or novel orthoebolaviruses that may cross-react.

Funding: Co-funding received through the program‘EBOVAC3 Bringing a prophylactic Ebola vaccine to licensure’ funded by IMI (Grant agreement number 800176) and run by LSTHM and INSERM, EBO-SURSY project funded by the European Union (FOOD/2016/379-660) and EBO-HEALTH project (Montpellier Université d'Excellence; I-Site MUSE, ANR-16-IDEX-0006).

Declaration of Interest: All other authors declare no competing interests.

Ethical Approval: Ethical approval for the study was obtained from the Guinea Ethics Committee [100/CNERS/19].

Keywords: Ebola Virus Disease, Seroprevalence, Guinea, Rural Population, Outbreak, Surveillance and Prevention Strategies