Ebola
Ebola, also known as Ebola virus disease (EVD) and Ebola hemorrhagic fever (EHF), is a viral hemorrhagic fever in humans and other primates, caused by ebolaviruses.[1] Symptoms typically start anywhere between two days and three weeks after infection.[3] The first symptoms are usually fever, sore throat, muscle pain, and headaches.[1] These are usually followed by vomiting, diarrhoea, rash and decreased liver and kidney function,[1] at which point some people begin to bleed both internally and externally.[1] It kills between 25% and 90% of those infected – about 50% on average.[1] Death is often due to shock from fluid loss, and typically occurs between six and 16 days after the first symptoms appear.[2] Early treatment of symptoms increases the survival rate considerably compared to late start.[4] An Ebola vaccine was approved by the US FDA in December 2019.
This article is about the disease. For other uses, see Ebola (disambiguation).Ebola
Ebola haemorrhagic fever (EHF), Ebola virus disease
Fever, sore throat, muscular pain, headaches, diarrhoea, bleeding[1]
Two days to three weeks post exposure[1]
Ebolaviruses spread by direct contact[1]
Finding the virus, viral RNA, or antibodies in blood[1]
Atoltivimab/maftivimab/odesivimab (Inmazeb)
25–90% mortality[1]
The virus spreads through direct contact with body fluids, such as blood from infected humans or other animals,[1] or from contact with items that have recently been contaminated with infected body fluids.[1] There have been no documented cases, either in nature or under laboratory conditions, of spread through the air between humans or other primates.[5] After recovering from Ebola, semen or breast milk may continue to carry the virus for anywhere between several weeks to several months.[1][6][7] Fruit bats are believed to be the normal carrier in nature; they are able to spread the virus without being affected by it.[1] The symptoms of Ebola may resemble those of several other diseases, including malaria, cholera, typhoid fever, meningitis and other viral hemorrhagic fevers.[1] Diagnosis is confirmed by testing blood samples for the presence of viral RNA, viral antibodies or the virus itself.[1][8]
Control of outbreaks requires coordinated medical services and community engagement,[1] including rapid detection, contact tracing of those exposed, quick access to laboratory services, care for those infected, and proper disposal of the dead through cremation or burial.[1][9] Prevention measures involve wearing proper protective clothing and washing hands when in close proximity to patients and while handling potentially infected bushmeat, as well as thoroughly cooking bushmeat.[1] An Ebola vaccine was approved by the US FDA in December 2019.[10] While there is no approved treatment for Ebola as of 2019,[11] two treatments (atoltivimab/maftivimab/odesivimab and ansuvimab) are associated with improved outcomes.[12] Supportive efforts also improve outcomes.[1] These include oral rehydration therapy (drinking slightly sweetened and salty water) or giving intravenous fluids, and treating symptoms.[1] In October 2020, atoltivimab/maftivimab/odesivimab (Inmazeb) was approved for medical use in the United States to treat the disease caused by Zaire ebolavirus.[13]
History and name
Ebola was first identified in 1976, in two simultaneous outbreaks, one in Nzara (a town in South Sudan) and the other in Yambuku (the Democratic Republic of the Congo), a village near the Ebola River, for which the disease was named.[1] Ebola outbreaks occur intermittently in tropical regions of sub-Saharan Africa.[1] Between 1976 and 2012, according to the World Health Organization, there were 24 outbreaks of Ebola resulting in a total of 2,387 cases, and 1,590 deaths.[1][14] The largest Ebola outbreak to date was an epidemic in West Africa from December 2013 to January 2016, with 28,646 cases and 11,323 deaths.[15][16][17] On 29 March 2016, it was declared to no longer be an emergency.[18] Other outbreaks in Africa began in the Democratic Republic of the Congo in May 2017,[19][20] and 2018.[21][22] In July 2019, the World Health Organization declared the Congo Ebola outbreak a world health emergency.[23]
Other animals
Wild animals
Ebola has a high mortality rate among primates.[271] Frequent outbreaks of Ebola may have resulted in the deaths of 5,000 gorillas.[272] Outbreaks of Ebola may have been responsible for an 88% decline in tracking indices of observed chimpanzee populations in the 420 km2 Lossi Sanctuary between 2002 and 2003.[273] Transmission among chimpanzees through meat consumption constitutes a significant risk factor, whereas contact between the animals, such as touching dead bodies and grooming, is not.[274]
Recovered gorilla carcasses have contained multiple Ebola virus strains, suggesting multiple introductions of the virus. Bodies decompose quickly and carcasses are not infectious after three to four days. Contact between gorilla groups is rare, suggesting that transmission among gorilla groups is unlikely, and that outbreaks result from transmission between viral reservoirs and animal populations.[273]
Domestic animals
In 2012, it was demonstrated that the virus can travel without contact from pigs to nonhuman primates, although the same study failed to achieve transmission in that manner between primates.[86][275]
Dogs may become infected with EBOV but not develop symptoms. Dogs in some parts of Africa scavenge for food, and they sometimes eat EBOV-infected animals and also the corpses of humans. A 2005 survey of dogs during an EBOV outbreak found that although they remain asymptomatic, about 32 percent of dogs closest to an outbreak showed a seroprevalence for EBOV versus nine percent of those farther away.[276] The authors concluded that there were "potential implications for preventing and controlling human outbreaks."