Definition of Ebola virus

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Ebola virus: A notoriously deadly virus that causes fearsome symptoms, the most prominent being high fever and massive internal bleeding. Ebola virus kills as many as 90% of the people it infects. It is one of the viruses that is capable of causing hemorrhagic (bloody) fever.

Epidemics of Ebola virus have occurred mainly in African countries including Zaire (now the Democratic Republic of Congo), Gabon, Uganda, the Ivory Coast, and Sudan. Ebola virus is a hazard to laboratory workers and, for that matter, anyone who is exposed to it.

Infection with Ebola virus in humans is incidental -- humans do not "carry" the virus. The way in which the virus first appears in a human at the start of an outbreak has not been determined. However, it has been hypothesized that the first patient (the index case) becomes infected through contact with an infected animal.

Ebola virus is transmitted by contact with blood, feces or body fluids from an infected person or by direct contact with the virus, as in a laboratory. People can be exposed to Ebola virus from direct contact with the blood or secretions of an infected person. This is why the virus has often been spread through the families and friends of infected persons: in the course of feeding, holding, or otherwise caring for them, family members and friends would come into close contact with such secretions. People can also be exposed to Ebola virus through contact with objects, such as needles, that have been contaminated with infected secretions.

The incubation period --the period between contact with the virus and the appearance of symptoms -- ranges from 2 to 21 days.

The initial symptoms are usually high fever, headache, muscle aches, stomach pain, and diarrhea. There may also be sore throat, hiccups, and red and itchy eyes. The symptoms that tend to follow include vomiting and rash and bleeding problems with bloody nose (epistaxis), spitting up blood from the lungs (hemoptysis) and vomiting it up from the stomach (hematemesis), and bloody eyes (conjunctival hemorrhages). Then finally come chest pain, shock, and death.

A protein on the surface of the virus has been discovered that is responsible for the severe internal bleeding (the death-dealing feature of the disease). The protein attacks and destroys the endothelial cells lining blood vessels, causing the vessels to leak and bleed.

There is no specific treatment for the disease. Currently, patients receive supportive therapy. This consists of balancing the patient's fluids and electrolytes, maintaining their oxygen level and blood pressure, and treating them for any complicating infections. Death can occur within 10 days of the onset of symptoms.

The prevention of the spread of Ebola fever involves practical viral hemorrhagic fever isolation precautions, or barrier nursing techniques. These techniques include the wearing of protective clothing, such as masks, gloves, gowns, and goggles; the use of infection-control measures, including complete equipment sterilization; and the isolation of Ebola fever patients from contact with unprotected persons. The aim of all of these techniques is to avoid any person's contact with the blood or secretions of any patient. If a patient with Ebola fever dies, it is equally important that direct contact with the body of the deceased patient be prevented.

Bioterrorism -- There has been concern about Ebola virus as a possible weapon for bioterrorism. However, the General Accounting Office, the investigative arm of the US Congress, in a 1999 report considered Ebola virus to be an "unlikely" biologic threat for terrorism, because the virus is very difficult to obtain and process, unsafe to handle, and relatively unstable.