Ebola virus disease (EVD), also known as Ebola haemorrhagic fever (EHF) or simply Ebola, is a viral hemorrhagic fever caused by ebolaviruses. It is a virus that causes severe bleeding, organ failure and often fatal in humans and nonhuman primates such as monkeys, chimpanzees and gorillas.
Ebola virus disease is named after a river called Ebola River in the Democratic Republic of the Congo (formerly Zaire) in Africa, where it was first recognized in 1976. The first outbreak of Ebola virus disease infected 318 people and caused 280 deaths, with a mortality rate of 88%.
The Ebola virus is contagious after a person develops symptoms, though not as contagious as more common viruses like colds, influenza, or measles. How the virus first infects a human at the start of an outbreak is unknown but is thought to be from an infected animal transmitted to humans, either by direct contact with the skin or bodily fluids of, or by eating infected wild animals.
Transmission of Ebola virus disease between humans can occur through:
Direct contact, through broken skin and mucous membranes with the blood, secretions, organs, or other body fluids of infected people.
Indirect contact with environments contaminated with such fluids.
Exposure to contaminated objects, such as needles.
Burial ceremonies in which mourners have direct contact with the body of the deceased.
Contact with patients with suspected or confirmed EVD. Healthcare workers have frequently been infected while treating patients.
There is no evidence that Ebola can be spread via insect bites, air or water.
What Causes Ebola Virus Disease?
Ebola is one of several viral haemorrhagic fevers, caused by infection with a virus of the Filoviridae family, genus Ebolavirus. The Ebola virus has been found in mostly African monkeys, chimpanzees, and other nonhuman primates. The natural reservoir (normal habitat) of Ebola viruses is unknown. However, researchers believe that the virus is zoonotic (animal-borne) with bats being the most likely reservoir.
There are five identified species (types) of Ebola virus. Four of the five have caused disease in humans:
Reston ebolavirus (known to cause disease in nonhuman primates and pigs, but not in humans)
The deadliest Ebola virus species is Zaire ebolavirus.
Risk Factors of Ebola Virus Disease
The risk of getting Ebola virus disease is low for most people. Most cases of illness or death have occurred in Africa. The risk increases if a person travels to or lives in where Ebola virus disease outbreaks have occurred. Those at highest risk include the following:
Health-care workers, and family and friends who have cared for an infected person with Ebola virus disease
Laboratory personnel working with bodily fluids of an Ebola virus disease patient
Animal researchers with direct handling of bats or primates from an area where Ebola virus disease has occurred
Individuals participating in funeral rites in which there is direct exposure to human remains where an Ebola virus disease outbreak is occurring
Signs and Symptoms of Ebola Virus Disease
Symptoms may appear anywhere from 2 to 21 days after exposure to Ebola virus, but an average of about 8 to 10 days is most common. Symptoms of Ebola virus infection are similar to those produced by other hemorrhagic fever viruses and include
joint and muscle pain,
loss of appetite.
These symptoms are followed by increasingly severe problems such as
Some patients may develop
a skin rash,
red spots on skin,
difficulty breathing, and
Late signs include the following:
Bleeding from inside and outside the body (eyes, ears, and nose)
Vomiting and/or coughing up blood
Failure of multiple organs (such as the lung, kidney, and liver)
Ebola virus infection can be highly contagious. A person becomes contagious when the first symptoms, like fever, begin to appear until the person dies. The person who dies leaves a body that is extremely contagious until the body is cremated or buried.
If an individual survives Ebola, the person remains contagious for approximately 21- 42 days after the symptoms abate. However, Ebola viruses have been detected in the eyes and in semen of Ebola survivors for months, breast milk, spinal column, and ocular fluids. It is not clear how contagious the virus is in these locations. Although it has been suggested that Ebola can be spread by semen and advised that male survivors of the disease should abstain from sex or use a condom for all sexual activity for six months; some experts suggest a longer time.
It is not known why some people survive from an infection with the Ebola virus. However, researchers have found that those who die from the disease are not able to develop an adequate immune response to the virus.
How to Diagnose Ebola Virus Disease
Diagnosing Ebola virus disease in a patient in the first few days is difficult, because the signs and symptoms are similar to more common illnesses. If a patient has risk factors for exposure to the Ebola virus and is suspected to be infected with it, the patient needs to be isolated and local and state health departments need to be immediately contacted. Then samples from the patient can be collected to confirm the diagnosis.
Antigen-capture enzyme-linked immunosorbent assay (ELISA) testing, IgM ELISA, polymerase chain reaction (PCR) to identify the genetic material of the virus, and virus isolation are all laboratory tests that can be used to diagnose an infected person within a few days when symptoms begin. Patients tested later in their disease or after recovery can be tested for IgM and IgG antibodies (immune response proteins directed against a part of the virus). In those who have died, immunohistochemistry testing (using antibody-linked stains and microscopic examination to detect a part of the virus in cells of a tissue sample), virus isolation, or PCR can be done.
Treatments for Ebola Virus Disease
Treatment for Ebola virus disease is still limited to supportive therapy in an intensive-care unit, which includes
intravenous (IV) fluids and electrolytes to treat dehydration,
maintaining blood pressure,
replacing blood through transfusions, and
treating additional infections that may develop subsequently.
There is no medical cure for Ebola virus disease because there is no licensed drug or vaccine available, but experimental therapy is being tried.
Experimental treatments have been tested and proven effective in animal models, but clinical trials to test effectiveness in humans have not been done.
The prognosis of Ebola is often poor and highly fatal and for those who do survive, recovery can be slow. They may develop inflammation of the eyes (uveitis), liver (hepatitis), or testicles (orchitis), as well as symptoms like, fatigue, weakness, chronic joint pains, or headaches.
However, early diagnosis and treatment of Ebola may greatly increase the patient's chance for survival.
There is currently no approved vaccine available for Ebola, although several are in development.
If you travel to or are in an area affected by an Ebola outbreak, make sure to do the following:
Practice careful hygiene. For example, wash your hands with soap and water or an alcohol-based hand sanitizer and avoid contact with blood and body fluids (such as urine, faeces, saliva, sweat, urine, vomit, breast milk, semen, and vaginal fluids).
Make sure fruits and vegetables are properly washed and peeled before you eat them.
Avoid physical contact with anyone who has possible symptoms of an infection.
Do not handle items that may have come in contact with an infected person’s blood or body fluids (such as clothes, bedding, needles, and medical equipment).
Don't handle dead animals or their raw meat.
Avoid funeral or burial rituals that require handling the body of someone who has died from Ebola.
Avoid contact with bats and nonhuman primates or blood, fluids, and raw meat prepared from these animals.
Avoid facilities where Ebola patients are being treated.
Avoid contact with semen from a man who has had Ebola until you know Ebola is gone from his semen.
After you return, monitor your health for 21 days and seek medical care immediately if you develop symptoms of Ebola.
Healthcare workers who may be exposed to people with Ebola should follow these steps:
Wear appropriate personal protective equipment (PPE).
Practice proper infection control and sterilization measures. Proper cleaning and disposal of instruments, such as needles and syringes, is important.
Isolate patients with Ebola from other patients.
Avoid direct, unprotected contact with the bodies of people who have died from Ebola.
Notify health officials if you have had direct contact with the blood or body fluids, such as but not limited to, faeces, saliva, urine, vomit, and semen of a person who is sick with Ebola. The virus can enter the body through broken skin or unprotected mucous membranes (like in the eyes, nose, or mouth).
Cleaners should use a bleach solution to clean floors and surfaces that may have come in contact with the Ebola virus.
there must be identification and isolation of infected individuals from the community,
tracing contacts, including those during the incubation period and
conducting proper public awareness and enlightenment.