There are four identified subtypes of Ebola virus. Three of the four have caused disease in humans: Ebola-Zaire, Ebola-Sudan, and Ebola-Ivory Coast. The fourth, Ebola-Reston, has caused disease in non-human primates, but not in humans.
There are more than four subtypes of Ebola virus. 
There have been 4 identified, but there could be more types of ebola virus out there not yet identified, or there could not be any more. 
( z1 virus :name ( z2 name :op "Ebola" ) :mod ( z3 subtype :quant ( z4 more-than :op 4 ) ) )