New evidence for endemic circulation of Ross River virus in the Pacific Islands and the potential for emergence.

•Ross River virus (RRV) is thought to be endemic only in Australia and Papua New Guinea, with marsupials as reservoirs.•Serological evidence is provided of endemic RRV circulation in American Samoa, where there are no marsupials.•The study findings imply that mammal species with pan-global distribution could act as reservoir hosts.•RRV could potentially become endemic well beyond its current know distribution.