Low seroprevalence of IgG antibodies to Ebola virus in an epidemic zone: Ogooue-Ivindo region, northeastern Gabon, 1997

A population-based serosurvey was performed to determine the seroprevalence of antibodies to Ebola virus (EBO) in a region that has experienced multiple epidemics of EBO hemorrhagic fever. Of 2533 residents in 8 villages, serum samples from 979 (38.6%) were tested by enzyme-linked immunosorbent assay for immunoglobulin (Ig) G and IgM antibodies to Ebola-Zaire (EBO-Z) virus. Fourteen samples (1.4%) were found positive for IgG antibodies, and 4 of these (.4%) were samples from survivors of an epidemic of EBO hemorrhagic fever. Seroprevalence based on the remaining 10 IgG-sero-positive individuals with no history of exposure to EBO was 1.0% (exact binomial 95% confidence interval, 0.5%-1.9%). No serum samples were found positive for IgM antibodies to EBO-Z virus. The low seroprevalence suggests that, outside of recognized outbreaks, human exposure to EBO in this epidemic zone is rare.