sentences:  However, the natural reservoirs of ebolaviruses are still unknown as of 2019.Megabats like the hammer-headed bat tend to be over-sampled relative to other potential Ebola virus hosts, meaning that they may have an unwarranted amount of research attention, and as of 2015, no bat hunter or researcher is known to be the index case ("patient zero") in an Ebola outbreak.As of 2016, it is evaluated as a least-concern species by the IUCN—its lowest conservation priority.