Nature: The Ebola questions
“…[T]he advances in knowledge about filoviruses [gained since their discovery in the 1960s] have also exposed the gaps. Scientists suspect that more members of the filovirus family remain to be discovered… They are also working to understand which animals naturally harbor filoviruses and why human filovirus outbreaks seem to be rising in frequency: they have occurred in 19 of the past 21 years, and three times this year alone. Finding answers is difficult because outbreaks are unpredictable and laboratory work with filoviruses requires the highest security measures…” (Hayden, 10/29).