Once Ebola virus infects the first human, scientists do know how Ebola virus is spread from human to human. Transmission of Ebola occurs through direct contact with patients who have Ebola, or their body fluids (such as blood or secretions). The late stage of an Ebola infection is the most common time for the spread of Ebola to occur.
When someone becomes infected with Ebola, he or she will not feel sick immediately. Although the virus is multiplying inside his or her body, the person typically feels normal for about 2 to 21 days after being infected. This period between transmission of the virus and the beginning of Ebola symptoms is called the Ebola incubation period.