Ebola virus (EBOV) is the sole member of the Zaire ebolavirus species and the most dangerous of the five known viruses within the genus Ebola virus. Four of the five known ebolaviruses cause a severe and often fatal hemorrhagic fever in humans and other mammals, known as Ebola virus disease. The virus and its species were both originally named for Zaire (now the Democratic Republic of Congo), the country where it was first described, and was at first suspected to be a new “strain” of the closely related Marburg virus; the virus (but not its species) was renamed to “Ebola virus” in 2010 to avoid confusion.
The species is a virological taxon species included in the genus Ebola virus, family Filoviridae (whose members are called Filovirus), order Mononegavirales. The Zaire ebolavirus species is also the type species (reference or example species) for ebola virus. Its natural reservoir is believed to be bats, particularly fruit bats, and it is primarily transmitted between humans and from animals to humans, through body fluids.
The EBOV genome is approximately 19,000 base pairs long. It encodes seven structural proteins: nucleoprotein (NP), polymerase cofactor(VP35), (VP40), GP, transcription activator (VP30), VP24, and RNA polymerase (L). It is difficult to study due to the virulent nature of the virus.
- Ebola virus disease (EVD), formerly known as Ebola hemorrhagic fever, is a severe, often fatal illness in humans.
- EVD outbreaks have a case fatality rate of up to 90%. EVD outbreaks occur primarily in remote villages in Central and West Africa, near tropical rainforests.
- The virus is transmitted to people from wild animals and spreads in the human population through human-to-human transmission.
- Fruit bats of the Pteropodidae family are considered to be the natural host of the Ebola virus.
- Severely ill patients require intensive supportive care. No licensed specific treatment or vaccine is available for use in people or animals.
Symptoms of Ebola typically include
- Fever (greater than 38.6°C or 101.5°F)
- Severe headache
- Muscle pain
- Abdominal (stomach) pain
- Lack of appetite
Ebola virus is one of the four ebolaviruses known to cause disease in humans. It has the highest case-fatality rate of these ebolaviruses, averaging 83% since first described in 1976, although fatality rates up to 90% have been recorded in one epidemic (2002–03). There have also been more outbreaks of ebola virus than of any other ebolavirus. The first outbreak occurred on 26 August 1976 in Yambuku. The first recorded case was Mabalo Lokela, a 44‑year-old schoolteacher. The symptoms resembled malaria, and subsequent patients received quinine. Transmission has been attributed to reuse of unsterilized needles and close personal contact, body fluids and places where the person has touched.
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Prolonged cases are often complicated by the occurrence of long-term problems, such as inflammation of the testicles, joint pains, muscle pains, skin peeling, or hair loss. Eye symptoms, such as light sensitivity, excess tearing, iritis, iridocyclitis, choroiditis, and blindness have also been described. EBOV and SUDV may be able to persist in the semen of some survivors for up to seven weeks, which could give rise to infections and disease via sexual intercourse.
Ebola virus was first isolated in 1976 during outbreaks of Ebola hemorrhagic fever in the Democratic Republic of the Congo (then Zaire) and Southern Sudan. The strain of Ebola that broke out in the Democratic Republic of the Congo had one of the highest case fatality rates of any human virus, 88%.