Ebola Virus Disease (EVD) is a rare and deadly disease most commonly affecting people and nonhuman primates (monkeys, gorillas, and chimpanzees). It is caused by an infection with a group of viruses within the type Ebolavirus.
Ebola virus was first discovered in 1976 near the Ebola River in what is now the Democratic Republic of Congo. Since then, the virus has been infecting people from time to time, leading to outbreaks in several African countries. Scientists do not know where Ebola virus comes from. However, based on the nature of similar viruses, they believe the virus is animal-borne, with bats being the most likely source. The bats carrying the virus can transmit it to other animals, like apes, monkeys, duikers and humans.
Ebola virus spreads to people through direct contact with bodily fluids of a person who is sick with or has died from EVD. This can occur when a person touches the infected body fluids (or objects that are contaminated with them), and the virus gets in through broken skin or mucous membranes in the eyes, nose, or mouth. The virus can also spread to people through direct contact with the blood, body fluids and tissues of infected fruit bats or primates. People can get the virus through sexual contact as well.
Scientists think people are initially infected with Ebola virus through contact with an infected animal, such as a fruit bat or nonhuman primate. This is called a spillover event. After that, the virus spreads from person to person, potentially affecting a large number of people.
The virus spreads through direct contact (such as through broken skin or mucous membranes in the eyes, nose, or mouth) with:
•Blood or body fluids (urine, saliva, sweat, feces, vomit, breast milk, and semen) of a person who is sick with or has died from Ebola Virus Disease (EVD)
•Objects (such as needles and syringes) contaminated with body fluids from a person sick with EVD or the body of a person who died from EVD
•Infected fruit bats or nonhuman primates (such as apes and monkeys)
•Semen from a man who recovered from EVD (through oral, vaginal, or anal sex). The virus can remain in certain bodily fluids (including semen) of a patient who has recovered from EVD, even if they no longer have symptoms of severe illness.
Symptoms of Ebola Virus Disease (EVD) are treated as they appear. When used early, basic interventions can significantly improve the chances of survival. These include:
•Providing fluids and electrolytes (body salts) through infusion into the vein (intravenously).
•Offering oxygen therapy to maintain oxygen status.
•Using medication to support blood pressure, reduce vomiting and diarrhea and to manage fever and pain.
•Treating other infections, if they occur.
Recovery from EVD depends on good supportive care and the patient’s immune response. Those who do recover develop antibodies that can last 10 years, possibly longer. It is not known if people who recover are immune for life or if they can later become infected with a different species of Ebola virus. Some survivors may have long-term complications, such as joint and vision problems.
There are currently two treatments approved by the U.S. Food and Drug Administration (FDA) to treat EVD caused by the Ebola virus, species Zaire ebolavirus, in adults and children.
The first drug approved in October 2020, Inmazeb. The second drug, Ebangaext, is a single monoclonal antibody and was approved in December 2020.
Drugs that are being developed to treat EVD work by stopping the virus from making copies of itself.
The Ebola virus vaccine
The Ebola virus (Zaire ebolavirus) vaccine is a live, attenuated recombinant virus (rVSV) vaccine. It is not possible to become infected with EBOV from the vaccine because the vaccine just contains a gene from the Ebola virus, not the whole virus.
The vaccine was approved by the U.S. Food and Drug Administration (FDA) on December 19, 2019 for the prevention of EVD caused by EBOV in people 18 years of age and older, based on the data from 12 clinical trials that included a total of 15,399 adults.