The Ebola virus, named after the river in Northern Zaire where it was discovered, is a RNA-containing, thread (or filament) shaped virus that causes severe bleeding and fever (hemorrhagic fever). Ebola was first identified following two major disease outbreaks occurring almost simultaneously in Zaire and Sudan in 1976. Because Ebola is similar in many respects to other viruses, researchers are interested in studying the mechanisms and rate of genetic mutations that affect the lethality and ability of viruses to spread. The virus is one of two members of a family of RNA viruses called the Filoviridae. They were originally classified as rhabdoviruses. However, genome sequencing revealed more of a similarity to paramyxoviruses. However, filoviruses are sufficiently distinct from the other nonsegmented negative-stranded RNA viruses to warrant taxonomic status as a separate virus family.

The disease, spread through direct contact with body secretions, is characterized by uncontrolled bleeding...