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Risk of Exposure

Risk of Exposure

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


Risk assessment in disease-endemic areas is difficult because the natural reservoir host of ebolaviruses, and the manner in which transmission of the virus to humans occurs remains unknown.

  • All cases of human illness or death have occurred in Africa (with the exception of several laboratory contamination cases: one in England and two in Russia)
    • No cases have been reported in the United States
    • In 2014, two U.S. healthcare workers who were infected with Ebola virus in Liberia were transported to a hospital in the United States.
  • Those at highest risk include
    • Healthcare workers
    • Family and friends of patients with Ebola

Healthcare workers in Africa should consult the Infection Control for Viral Hemorrhagic Fevers in the African Health Care Setting to learn how to prevent and control infections in these setting. Medical professionals in the United States should consult the Interim Guidance for Managing Patients with Suspected Viral Hemorrhagic Fever in U.S. Hospitals [PDF - 4 pages] .

Past Ebola Outbreaks

Past Ebola outbreaks have occurred in the following countries:

  • Democratic Republic of the Congo (DRC)
  • Gabon
  • South Sudan
  • Ivory Coast
  • Uganda
  • Republic of the Congo (ROC)
  • South Africa (imported)

Current Ebola Outbreak in West Africa

The current (2014) Ebola outbreak is occurring in the following West African countries:

  • Guinea
  • Liberia
  • Sierra Leone
  • Nigeria