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| English: Transmission Electron Micrograph of the Ebola Virus. Hemorrhagic Fever, RNA Virus. Français : Virus Ebola. Italiano: Fotografia al microscopio elettronico della trasmissione del virus Ebola. Русский: Изображение вируса Эбола полученное с помощью просвечивающей электронной микроскопии. 中文: 電子顯微鏡下的伊波拉病毒結構. Türkçe: Ebola virüsü. Føroyskt: Ebola virus, eitt (-)ssRNA virus, undir elektronmikroskopi. (Photo credit: Wikipedia) |
Ebola virus disease (EVD), formerly known as Ebola haemorrhagic fever, is a severe, often fatal illness in humans. Signs and symptoms typically start between two days and three weeks after contracting the virus, with a fever, sore throat, muscle pain and headaches. Then, vomiting, diarrhoea and rash usually follows, along with decreased function of the liver and kidneys. At this time, generally, some people begin to bleed both internally and externally. Death, if it occurs, is typically six to sixteen days after symptoms appear and is often due to low blood pressure from fluid loss.
The virus is acquired by contact with blood or other body fluids of an infected human or other animal. This may also occur by direct contact with a recently contaminated item. Spread through the air has not been documented in the natural environment. Fruit bats are believed to be the normal carrier in nature, able to spread the virus without being affected. Humans become infected by contact with the bats or a living or dead animal that has been infected by bats. Once human infection occurs, the disease may spread between people as well. Male survivors may be able to transmit the disease via semen for nearly two months. To diagnose EVD, other diseases with similar symptoms such as malaria, cholera and other viral haemorrhagic fevers are first excluded. Blood samples are tested for viral antibodies, viral RNA, or the virus itself to confirm the diagnosis.
The Ebola virus causes an acute, serious illness which is often fatal if untreated. Ebola virus disease (EVD) first appeared in 1976 in 2 simultaneous outbreaks, one in Nzara, Sudan, and the other in Yambuku, Democratic Republic of Congo. The latter occurred in a village near the Ebola River, from which the disease takes its name.
The current outbreak in west Africa, (first cases notified in March 2014), is the largest and most complex Ebola outbreak since the Ebola virus was first discovered in 1976. There have been more cases and deaths in this outbreak than all others combined. It has also spread between countries starting in Guinea then spreading across land borders to Sierra Leone and Liberia, by air (1 traveller only) to Nigeria, and by land (1 traveller) to Senegal.
The most severely affected countries, Guinea, Sierra Leone and Liberia have very weak health systems, lacking human and infrastructural resources, having only recently emerged from long periods of conflict and instability. On August 8, the WHO Director-General declared this outbreak a Public Health Emergency of International Concern.
A separate, unrelated Ebola outbreak began in Boende, Equateur, an isolated part of the Democratic Republic of Congo.
The virus family Filoviridae includes 3 genera: Cuevavirus, Marburgvirus, and Ebolavirus. There are 5 species that have been identified: Zaire, Bundibugyo, Sudan, Reston and Taï Forest. The first 3, Bundibugyo ebolavirus, Zaire ebolavirus, and Sudan ebolavirus have been associated with large outbreaks in Africa. The virus causing the 2014 west African outbreak belongs to the Zaire species.
Outbreak control requires a coordinated series of medical services, along with a certain level of community engagement. The necessary medical services include rapid detection and contact tracing, quick access to appropriate laboratory services, proper management of those who are infected, and proper disposal of the dead through cremation or burial. Prevention includes decreasing the spread of disease from infected animals to humans. This may be done by only handling potentially infected bush meat while wearing protective clothing and by thoroughly cooking it before consumption. It also includes wearing proper protective clothing and washing hands when around a person with the disease. Samples of body fluids and tissues from people with the disease should be handled with special caution.
No specific treatment for the disease is yet available. Efforts to help those who are infected are supportive and include giving either oral rehydration therapy (slightly sweetened and salty water to drink) or intravenous fluids. This supportive care improves outcomes. The disease has a high risk of death, killing between 25% and 90% of those infected with the virus, averaging out at 50%. EVD was first identified in an area of Sudan (now part of South Sudan), as well as in Zaire (now the Democratic Republic of the Congo). The disease typically occurs in outbreaks in tropical regions of sub-Saharan Africa. From 1976 (when it was first identified) through 2013, the World Health Organization reported a total of 1,716 cases. The largest outbreak to date is the ongoing 2014 West African Ebola outbreak, which is currently affecting Guinea, Sierra Leone, and Liberia. As of 22 October 2014, 9,964 suspected cases resulting in the deaths of 4,881 have been reported. Efforts are under way to develop a vaccine.
Symptoms of Ebola are treated as they appear. The following basic interventions, when used early, can significantly improve the chances of survival:
- Providing intravenous fluids (IV)and balancing electrolytes (body salts)
- Maintaining oxygen status and blood pressure
- Treating other infections if they occur
- Experimental vaccines and treatments for Ebola are under development, but they have not yet been fully tested for safety or effectiveness.
Recovery from Ebola depends on good supportive care and the patient's immune response. People who recover from Ebola infection develop antibodies that last for at least 10 years, possibly longer. It isn't known if people who recover are immune for life or if they can become infected with a different species of Ebola. Some people who have recovered from Ebola have developed long-term complications, such as joint and vision problems.
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