Serologic evidence of orthomarburgviruses and an orthoebolavirus in frugivorous Malagasy bats.

Recent outbreaks of Marburg virus disease in regions of sub-Saharan Africa without prior record such as Ghana, Tanzania, Equatorial Guinea, and Rwanda challenge the current understanding of areas at-risk for filovirus spillover. The orthomarburgvirus host Rousettus aegyptiacus exists in these regions, and has a sister species, Rousettus madagascariensis, native only to the island of Madagascar. We expand on previous surveillance of frugivorous bats in Madagascar, and detect seroreactivity against an orthoebolavirus antigenically-related to Bundibugyo virus at 1.50-5.06% seroprevalence in Rousettus madagascariensis. Notably, we identify R. madagascariensis as an orthomarburgvirus-host species of interest in Madagascar, the first record of this virus genus on the island. We document seroprevalences of 15.36-29.78% for Ravn virus and 12.55-33.33% for Marburg virus in R. madagascariensis. These findings will guide future biosurveillance efforts to assess filovirus spillover risk in Madagascar.