Ebola Virus Disease (EVD)

West Africa Outbreak - Outbreak of Ebola in Guinea, Liberia, and Sierra Leone

Ebola, previously known as Ebola hemorrhagic fever, is a rare and deadly disease caused by infection with one of the Ebola virus strains. Ebola can cause disease in humans and nonhuman primates (monkeys, gorillas, and chimpanzees).

Ebola is caused by infection with a virus of the family Filoviridae, genus Ebolavirus. There are five identified Ebola virus species, four of which are known to cause disease in humans: Ebola virus (Zaire ebolavirus); Sudan virus (Sudan ebolavirus); Taï Forest virus (Taï Forest ebolavirus, formerly Côte d’Ivoire ebolavirus); and Bundibugyo virus (Bundibugyo ebolavirus). The fifth, Reston virus (Reston ebolavirus), has caused disease in nonhuman primates, but not in humans.

Ebola viruses are found in several African countries. Ebola was first discovered in 1976 near the Ebola River in what is now the Democratic Republic of the Congo. Since then, outbreaks have appeared sporadically in Africa.

The natural reservoir host of Ebola virus remains unknown. However, on the basis of evidence and the nature of similar viruses, researchers believe that the virus is animal-borne and that bats are the most likely reservoir. Four of the five virus strains occur in an animal host native to Africa.

For guidance on Ebola from the Department of Health and Human Services in Helena, Montana, please click on the link below

DPHHS State of Montana


For more information on Ebola for the general public from the CDC Centers for Disease Control and Prevention please click on the links below

FAQ’s Frequently asked Questions

Latest information on Cases of Ebola Diagnosed in the United States

Latest Outbreak in West Africa Information

Signs and Symptoms


Risk of Exposure





For more information on Ebola for Healthcare Workers from the CDC Centers for Disease Control and Prevention please click on the link below

Information for Healthcare Workers and Settings