The Ebola virus, classified as a Risk Group 4 pathogen by the World Health Organization, is a highly virulent hemorrhagic fever virus. It causes severe symptoms including fever, intense headache, diarrhea, vomiting, and a critical disruption of the body's coagulation system, leading to internal bleeding from small blood vessels. Ebola Virus Disease (EVD) results in severe systemic inflammation, extensive tissue damage, and is often fatal. There are five known species of the Ebola virus; however, only four of these are recognized to cause disease in humans. These pathogenic species – Bundibugyo, Sudan, Zaire, and Tai Forest ebolaviruses – are responsible for outbreaks and high fatality rates. The Reston ebolavirus is known to infect non-human primates and can infect humans, but it has not been linked to illness in humans.