Nearly 75% of emerging infectious diseases (EIDs) affecting humans are of zoonotic origin. Of these, many are caused by single-strand RNA bat-borne viruses, such as Ebola virus (EBOV), Marburg virus (MARV) and Nipah virus (NiV).
There are often many differences in the symptoms between the natural, transmission and human hosts. For instance, NiV can reach a fatality rate of up to 92% in humans; however bats can support high levels of virus replication in the absence of disease. The mechanisms responsible for such differences are yet to be determined.