Ebola hemorrhagic fever is a severe, often-fatal disease in humans and primates that has appeared sporadically since its initial recognition in 1976. Cases of Ebola are reported all over Africa, including Democratic Republic of the Congo, Gabon, Sudan, the Ivory Coast, Uganda, and the Republic of the Congo. Ebola in humans has never been reported in the United States however.
The disease is caused by infection with Ebola virus, first discovered in Africa. The virus is one of two members of a family of RNA viruses called the Filoviridae. There are five identified subtypes of Ebola virus. Four of the five have caused disease in humans: Ebola-Zaire, Ebola-Sudan, Ebola-Ivory Coast and Ebola-Bundibugyo. The fifth, Ebola-Reston, has caused disease only in primates.
The viruses natural reservoir is currently unknown, although the majority of scientists belive it is Zoonotic, or animal-borne. Ebola is native to Africa.
Since the natural reservoir for the virus is unknown, how Ebola first appeared in humans is not currently not known. Scientist believe that infection in humans started after exposure to the animal reservoir. After initial infection, the disease can pass from person to person in several ways. Ebola can be transmitted through contact with infected blood. Also, needles with infected secretions can provide a route for infection.
After exposure to the virus, Ebola incubates for 2–21 days. The symptoms tend to be abrupt, and are characterized by a fever, headache, muscle aches, followed by diarrhea, vomiting, and stomach pain. In some patients, rashes, red eyes, hiccups, and external/internal bleeding may occur.