What is Ebola Virus Disease ?
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 one of five known Ebola virus species, four of which can cause disease in people:
Ebola virus (Zaire ebolavirus)Sudan virus (Sudan ebolavirus)Taï Forest virus (Taï Forest ebolavirus, formerly Côte d’Ivoire ebolavirus)Bundibugyo virus (Bundibugyo ebolavirus)Reston virus (Reston ebolavirus), known to cause disease in nonhuman primates and pigs, but not in people
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.
Ebola survivors may experience difficult side effects after their recovery, such as tiredness, muscle aches, eye and vision problems and stomach pain. Survivors may also experience stigma as they re-enter their communities.
Transmission
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 EVDObjects (such as needles and syringes) contaminated with body fluids from a person sick with EVD or the body of a person who died from EVDInfected 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 Ebola virus CANNOT spread to others when a person shows no signs or symptoms of Ebola Virus Disease (EVD). Additionally, Ebola virus is not usually transmitted by food. However, in certain parts of the world, Ebola virus may spread through the handling and consumption of bushmeat (wild animals hunted for food). There is also no evidence that mosquitoes or other insects can transmit Ebola virus.
Persistence of the virus
Ebola virus can remain in certain body fluids after a person has recovered from the infection. These fluids are semen, breast milk, ocular (eye) fluid, and spinal column fluid. Areas of the body that contain these fluids are known as immunologically privileged sites. These are sites of the body where viruses and pathogens, like Ebola virus, can remain undetected even after the immune system has cleared the virus from other sites of the body. Scientists are now studying how long the virus stays in these body fluids among Ebola survivors.
During an Ebola outbreak, the virus can spread quickly within healthcare settings (such as clinics or hospitals). Clinicians and other healthcare personnel providing care should use dedicated medical equipment, preferably disposable. Proper cleaning and disposal of instruments such as needles and syringes are important. If instruments are not disposable, they must be sterilized before additional use.
Signs and Symptoms
Symptoms of Ebola Virus Disease (EVD) include:
FeverSevere headacheMuscle painWeaknessFatigueDiarrheaVomitingAbdominal (stomach) painUnexplained hemorrhage (bleeding or bruising)
Symptoms may appear anywhere from 2 to 21 days after contact with the virus, with an average of 8 to 10 days. Many common illnesses can have these same symptoms, including influenza (flu) or malaria.
EVD is a rare but severe and often deadly disease. Recovery from EVD depends on good supportive clinical care and the patient’s immune response. Studies show that survivors of Ebola virus infection have antibodies (molecules that are made by the immune system to label invading pathogens for destruction) that can be detected in the blood up to 10 years after recovery.
