Abstract
Background Ebola (EBOV) and Sudan (SUDV) orthoebolaviruses are responsible for lethal haemorrhagic fever outbreaks in humans in Central and West Africa, and in apes that can be at the source of human outbreaks for EBOV. Methods To assess the risk of exposure to orthoebolaviruses through contact with non-human primates (NHP), we tested the presence of antibodies against different viral proteins with a microsphere-based multiplex immunoassay in a case-control study on bites from NHPs in forest areas from Cameroon (n=795), and in cross-sectional surveys from other rural populations (n=622) of the same country. Results Seroreactivities against at least two viral proteins were detected in 13% and 12% of the samples for EBOV and SUDV, respectively. Probability of seroreactivity was not associated with history of NHP bites, but was three times higher in Pygmies compared to Bantus. Although no neutralizing antibodies to EBOV and SUDV were detected in a selected series of highly reactive samples, avidity results indicate strong affinity to SUDV antigens. Conclusion The detection of high level of seroreactivities against orthoebolaviruses in rural Cameroon where no outbreaks have been reported, raises the possibilities of silent circulation of orthoebolavirus, or of other not yet documented filoviruses, in these forested regions.