Ebola virus

The Ebola Virus disease (EVD) is a very deadly viral infection, claiming the lives of 50–90% of individuals who catch the virus. It most commonly affects humans and primates like monkeys, gorillas, and chimpanzees, and is endemic in central and sub-Saharan Africa. It was first discovered in 1976 near the Ebola river (from which it is named) in what is now the Democratic Republic of Congo.

Last Updated: September 27, 2023

There are six known species of viruses within the genus Ebolavirus:
1. Ebola virus (Zaire ebolavirus)
2. Sudan virus (Sudan ebolavirus)
3. Tai Forest virus (Tai Forest ebolavirus)
4. Bundibugyo ebolavirus (Bundibugyo ebolavirus)
5. Reston virus (Reston ebolavirus)
6. Bombali virus (Bombali ebolavirus)

Only four of the six are known to cause disease in humans: the Ebola, Sudan, Tai Forest, and Bundibugyo viruses. The Reston virus, which has been found circulating in the Philippines, is known to cause disease in nonhuman primates and pigs, but not in humans. It is still unknown if the Bombali virus, which was recently identified in bats, can cause disease in other animals or in humans.

EVD can be spread through direct contact (through broken skin or mucous membrane) with blood, secretions, or other body fluids of infected people, or surfaces and materials contaminated with these fluids. People remain infectious even after they have passed away.

Signs and symptoms of the disease may appear 2 days to 3 weeks after exposure to the virus, but the average is 8–10 days. A person infected with Ebola virus is not contagious until symptoms appear. Initial symptoms may include:
• Fever
• Headache
• Nausea/vomiting
• Diarrhea
• Muscle pain
• Rashes

Severe signs of disease are mostly associated with hemorrhage or bleeding. These include:
• Redness of eyes
• Bruising
• Gum bleeding
• Low blood pressure
• Headache, confusion, or unconsciousness

There is currently no proven treatment available for the disease. There are several new treatments being studied, like administering a mixture of antibodies or the serum of someone who survived the virus, but these have only been tested out in a limited number of individuals.

Instead, symptoms of EVD are treated as they appear. Aggressive supportive care is typically required, which usually involves rehydration with oral or intravenous fluids, nutritional support, blood transfusion, and treatment of bleeding problems. These, alongside treatment of specific symptoms, improve the chances of the patient’s survival. If present, secondary infections (i.e., other infections occurring alongside the Ebola virus infection) should also be addressed.

Practicing good hand hygiene is an effective method of preventing the spread of Ebola virus. Proper hand hygiene means frequently washing hands with soap and water or applying an alcohol-based hand sanitizer.

While in an area affected by Ebola virus, one should avoid:
• Contact with blood and body fluids (such as urine, feces, saliva, sweat, vomit, breast milk, semen, and vaginal fluids).
• Items that may have contact with an infected person's blood or body fluids (such as clothes, bedding, needles, and medical equipment).
• Funeral or burial rituals that require handling the body of someone who died from EVD.
• Contact with bats and nonhuman primates, or with blood, fluids, and raw meat prepared from these animals, or meat from an unknown source.

To date, at least four different vaccines have been developed against the Zaire Ebola virus, with some of them showing promising protective effects of up to a year after vaccination. Recently, UNICEF, WHO, IFRC, and MSF have established a large stock of one of these vaccines, the rVSV-ZEBOV vaccine, for use in Ebola outbreaks.

Last Updated: September 27, 2023