Ebola virus disease is a serious, usually fatal, disease for which there are no licensed treatments or vaccines. But for people living in countries outside Africa, it remains a very low threat.
Ebola was first identified in Africa in the mid-1970s. An outbreak that began in March 2014 was the most serious so far. By August 13 2014 it had killed more than 1,000 people across Guinea, Liberia, Sierra Leone and Nigeria.
How do Ebola outbreaks start?
It's thought the Ebola virus has been living harmlessly in fruit bats for many years, building up in this population and spreading to other forest animals including chimpanzees and gorillas.
It's likely the virus makes its way into people after they butcher or handle dead animals contaminated with the virus.
How does it spread among people?
People can become infected with the Ebola virus if they come into contact with the blood, body fluids or organs of an infected person.
Most people are infected by giving care to other infected people, either by directly touching the victim's body or by cleaning up body fluids (stools, urine or vomit) that carry infectious blood.
Traditional African burial rituals have also played a part in its spread. The Ebola virus can survive for several days outside the body, including on the skin of an infected person, and it's common practice for mourners to touch the body of the deceased. They only then need to touch their mouth to become infected.
Other ways people can catch Ebola are:
- touching the soiled clothing of an infected person, then touching their mouth
- having sex with an infected person without using a condom (the virus is present in semen for up to seven weeks after the infected person has recovered)
- handling unsterilised needles or medical equipment that were used in the care of the infected person
A person is infectious as long as their blood, urine, stools or secretions contain the virus.
Ebola virus disease is generally not spread through routine social contact (such as shaking hands) with patients who do not have symptoms.
The virus is not, for example, as infectious as diseases like the flu, as airborne transmission is much less likely. You'd need to have close contact with the source of infection to be at risk.
Who is at risk?
Anyone who cares for an infected person or handles their blood or fluid samples is at risk of becoming infected. Hospital workers, laboratory workers and family members are at greatest risk.
Strict infection control procedures and wearing protective clothing minimises this risk – Simply washing hands with soap and water can destroy the virus.
What are the symptoms?
An infected person will typically develop a fever, headache, joint and muscle pain, sore throat, and intense muscle weakness. These symptoms start suddenly, between 2 and 21 days after becoming infected, but usually after 5-7 days.
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Ebola virus disease is fatal in 50-90% of cases. The sooner a person is given care, the better the chances that they will survive.
Signs and symptoms of Ebola usually begin suddenly with an influenza-like stage characterized by fatigue, fever, headaches, joint, muscle, and abdominal pain. Vomiting, diarrhea, and loss of appetite are also common. Less common symptoms include the following: sore throat, chest pain, hiccups, shortness of breath, and trouble swallowing. Skin manifestations may include maculopapular rash (in about 50% of cases). Early symptoms of EVD may be similar to those of malaria, dengue fever, or other tropical fevers, before the disease progresses to the bleeding phase.
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In 40–50% of cases, bleeding from puncture sites and mucous membranes (e.g., gastrointestinal tract, nose, vagina, and gums) has been reported. In the bleeding phase, which typically begins five to seven days after first symptoms, internal and subcutaneous bleeding may present itself in the form of reddened eyes and bloody vomit. Bleeding into the skin may create petechiae, purpura, ecchymoses, andhematomas (especially around needle injection sites). Sufferers may cough up blood, vomit it, or excrete it in their stool.
Heavy bleeding is rare and is usually confined to the gastrointestinal tract. In general, the development of bleeding symptoms often indicates a worse prognosis and this blood loss can result in death All people infected show some signs of circulatory system involvement, including impaired blood clotting. If the infected person does not recover, death due to multiple organ dysfunction syndrome occurs within 7 to 16 days (usually between days 8 and 9) after first symptoms
How is it diagnosed?
The diagnosis is confirmed by isolating the virus, detecting
its RNA or proteins, or detecting antibodies against the virus
in a person's blood. Isolating the virus by cell culture,
detecting the viral RNA by polymerase chain reaction (PCR)
and detecting proteins by enzyme-linked immunosorbent
assay (ELISA) works best early and in those who have died
from the disease. Detecting antibodies against the virus
works best late in the disease and in those who recover.
A suspect case would be isolated in a side room so as to minimise contacts with other people while they are being tested. It is only if this test is positive that the case is considered to be ‘confirmed’.
If the test is positive then they will be transferred to a hospital-based high-level isolation unit.
If the result is negative, doctors will test for other diseases such as malaria, typhoid fever and cholera.
How is it treated?
There's currently no licensed treatment or vaccine for Ebola virus disease, although potential new vaccines and drug therapies are being developed and tested.
Patients need to be placed in isolation in intensive care. Dehydration is common, so fluids may be given directly into a vein (intravenously). Blood oxygen levels and blood pressure need to be maintained at the right level and body organs supported while the patient's body fights the disease and any other infections are treated.
ZMapp is an experimental treatment that can be tried, although it has not yet been tested in humans for safety or effectiveness. The product is a combination of three different antibodies that bind to the protein of the Ebola virus.
What's the advice for healthcare and aid workers?
Any area affected by an outbreak should be immediately quarantined and patients treated in isolation.
Healthcare workers need to avoid contact with the bodily fluids of their infected patients by taking the following precautions:
- wear face masks, goggles, gowns and gloves
- take extra care when handling blood, secretions and catheters and when connecting patients to a drip
- disinfect non-disposable medical equipment before re-use
- sterilise and dispose of used needles and disposable equipment carefully
- properly dispose of any secretions or body waste from the patient
- carefully and frequently wash hands with soap and water (alcohol hand rub if soap isn't available)
- wash disposable gloves with soap and water after use, dispose of them carefully, then wash hands
What's the advice for travellers in at-risk areas?
Following these simple precautions will minimise your risk of catching Ebola virus disease:
- don't handle dead animals or their raw meat
- don't eat 'bushmeat'
- avoid contact with patients who have symptoms
- avoid having sex with people in risk areas; use a condom if you do
- make sure fruit and veg is washed and peeled before you eat it
- wash hands frequently using soap and water (alcohol hand rubs when soap is not available), as this destroys the virus
If you think you or a family member has symptoms of Ebola infection:
- visit a healthcare provider immediately and inform them that you may have had contact with the Ebola virus (the nearest Embassy or Consular Office can help you find a provider in the area)
- limit contact with others and avoid all other travel
It's more likely that the cause is another disease such as malaria, but you may need to be tested for Ebola as a precaution.
Prevention and control
Good outbreak control relies on applying a package of interventions, namely case management, surveillance and contact tracing, a good laboratory service, safe burials and social mobilisation. Community engagement is key to successfully controlling outbreaks. Raising awareness of risk factors for Ebola infection and protective measures that individuals can take is an effective way to reduce human transmission. Risk reduction messaging should focus on several factors:
- Reducing the risk of wildlife-to-human transmission from contact with infected fruit bats or monkeys/apes and the consumption of their raw meat. Animals should be handled with gloves and other appropriate protective clothing. Animal products (blood and meat) should be thoroughly cooked before consumption.
- Reducing the risk of human-to-human transmission from direct or close contact with people with Ebola symptoms, particularly with their bodily fluids. Gloves and appropriate personal protective equipment should be worn when taking care of ill patients at home. Regular hand washing is required after visiting patients in hospital, as well as after taking care of patients at home.
- Outbreak containment measures including prompt and safe burial of the dead, identifying people who may have been in contact with someone infected with Ebola, monitoring the health of contacts for 21 days, the importance of separating the healthy from the sick to prevent further spread, the importance of good hygiene and maintaining a clean environment.
Key Words:Ebola Virus,History ,Epidemiology ,Sign & symptoms,Diagnosis, Treatment & Prevention,ZMaap,)
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