The epidemiological data detailing the number of Ebola cases is updated by the World Health Organization (WHO).
You can read their DAILY Situation Summary. For graphs, geographical distribution and more details see the WEEKLY report (on Wednesdays).
WHO Ebola virus case classification
A probable or suspected case becomes CONFIRMED when a sample from that person tests positive for EVD in laboratory.
A suspected case (evaluated by a clinician) or person who died from suspected EVD and had an epidemiological link to a confirmed case (but was not tested and did not have laboratory confirmation of the disease) becomes PROBABLE.
Any person, alive or dead, who has/had Ebola symptoms and had contact with a suspected, probable or confirmed EVD case, or a dead or sick animal or with any person with unexplained bleeding or any sudden, unexplained death becomes SUSPECTED.