This digitally-colorized scanning electron micrograph (SEM) depicts a single filamentous Ebola virus particle that had budded from the surface of a VERO cell of the African green monkey kidney epithelial cell line. Ebola hemorrhagic fever (Ebola HF) is one of numerous Viral Hemorrhagic Fevers. It is a severe, often fatal disease in humans and nonhuman primates (such as monkeys, gorillas, and chimpanzees). Ebola HF is caused by infection with a virus of the family Filoviridae, genus Ebolavirus. When infection occurs, symptoms usually begin abruptly. The first Ebolavirus species was discovered in 1976 in what is now the Democratic Republic of the Congo near the Ebola River.