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Article

About ebola

How Ebola is transmitted, how to protect oneself, about the risks for travelling to affected areas, etc.

CDC, Frederick Murphy
CDC, Frederick Murphy

How Ebola is transmitted, how to protect oneself, about the risks for travelling to affected areas, etc.


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Ebola is a serious, often fatal infection caused by a virus. Ebola is transmitted through direct contact with bodily fluids from an infected person. These body fluids include blood, urine, faeces and vomit.

The Ebola outbreak in West Africa in 2014 is the largest to date, affecting thousands of people. The chance of being infected in Norway is minimal.

How is Ebola transmitted?

During an outbreak, the Ebola virus transmits from person to person through direct contact with blood and other bodily fluids. In outbreak areas, family members and others in close contact with sick and deceased patients are most often infected. In addition, healthcare personnel who treat the sick without adequate infection control measures are exposed to infection. The virus is not transmitted in the time from infection until symptoms appear (incubation period).

The transmission risk increases during the course of the disease and is greatest during the bleeding stage because of the increased possibility of coming into contact with blood and other bodily fluids from patients.

Ebola virus is not spread through the air (for example, when someone coughs or sneezes) or through casual contact (for example, being in the same building as someone with Ebola or passing them on the street).
 
The symptoms develop within 21 days after the virus enters the body. If someone who has been close to a sick person has not developed symptoms during this time, they have not been infected.

What is the difference between "airborne" and "droplet" transmission?

There are three different terms used which are often mixed and cause confusion:

  • Aerosols are small, fine solid or liquid particles suspended in a gas (such as air). Coughing, sneezing, breathing, vomiting and talking are examples of activities that form aerosols of various sizes. 
  • Droplets greater than 5-10 micrometres fall to the ground or stick to other surfaces within seconds and will not travel further than one metre. When viruses or bacteria are transmitted via such large drops, this is called droplet transmission. 
  • Smaller droplets may remain in the air for long periods and will quickly evaporate, with the result that their contents remain in a free state in the air. These are called "droplet nuclei" and can remain suspended in the air for hours. If the virus or bacteria can infect others through droplet nuclei, we call it airborne transmission.

Activities such as vomiting and coughing generate both droplets and droplet nuclei. 

Based on current knowledge, there is no reason to suspect that Ebola infects humans via airborne transmission. The cause is not fully understood, but it may be because the virus does not tolerate drying up and / or other factors it encounters outdoors. However, it is likely that infection can occur by droplet infection, where droplets of bodily fluids from Ebola patients, particularly blood or vomit, enter the mucosa through the eyes, nose or mouth. 

Infection can thus probably occur from droplets near a sick patient (up to 1 metre). But there are no signs that Ebola can be transmitted via airborne infection, i.e. via droplet nuclei. By far the most common cause of infection is still direct contact with the body fluids of a sick person.

What are the symptoms?

Symptoms of Ebola virus disease include a severe headache, high fever, weakness, muscle pain, vomiting, diarrhoea, and rash. After 5-7 days, internal and external bleeding may occur. Mortality from Ebola virus disease in the current outbreak in West Africa seems to be around 50-60 per cent. The time from infection to the appearance of symptoms (incubation period) is usually 2-21 days.

Is there any treatment?

There is no approved treatment for Ebola virus disease. Patients require good care and treatment of symptoms in hospital. For the current outbreak in West Africa, the World Health Organization has declared that they will allow the use of some unapproved medicines that show promising results in laboratory and animal tests.

Can health workers completely protect themselves from infection?

We can never give a one hundred per cent guarantee that health care workers will not be infected by any infectious disease. Ebola is transmitted by contact with a sick person or their bodily fluids. As Ebola is such a serious illness, we recommend that the procedures are followed as if the infection was also potentially airborne. Hospitals in Norway that can accept Ebola patients have established very strict security routines. 

A critical point in contact with Ebola patients can be when removing protective equipment. This must done be done very carefully to avoid contact with any viruses on the suits. Personnel in the Norwegian hospital departments that may receive Ebola patients should practise dressing and undressing from protective suits. The isolation unit at Oslo University Hospital, Ullevål has been treating a patient with Ebola and the procedures, facilities and equipment in place will safeguard the employees’ safety in the best possible way.

Does previous Ebola disease protect against reinfection?

Studies done during previous Ebola outbreaks indicate that most survivors of an Ebola infection form antibodies and cellular immunity against the Ebola virus. Only a few and relatively small studies have looked at this. Most studies support the theory of protective immunity after infection, but individual data from both human and non-human studies show conflicting results.

It is likely that survivors have some protection against reinfection, especially against the same Ebola strain, but it is currently uncertain to what extent and how long this protection lasts, and whether everyone who undergoes the infection develops such protective immunity. It is therefore recommended that people who have undergone Ebola infection use the same protective equipment and follow the same routines as others during work, or other contact with Ebola patients.

How does an outbreak of Ebola start?

The Ebola virus can be found in a variety of wildlife species in Africa. An outbreak starts when a person is infected by an animal. This person may then transmit the virus to others through direct contact with blood and other body fluids/secretions from someone who is sick. The risk of infection is greatest when the patient is bleeding. The first outbreak of Ebola was in 1976 and since then there have been numerous smaller outbreaks in Africa.

How does the Ebola virus damage the body?

The immune cells are infected first, but then the virus also attacks other cells in the body. The liver is the organ where cell damage is most widespread, but the spleen, lungs and kidneys are also damaged. Thin capillary walls are damaged, which allows plasma to leak and bleeding. After a while, the body may go into a state of shock.

The progress of Ebola depends on many factors, including the immune system, route of infection, viral load and genetic factors in the infected person. In severe cases, multiple organ failure and shock may occur.

Can Ebola be spread through the air-conditioning system on a plane?

Ebola is not transmitted via airborne transmission and there is therefore no risk of being infected through the air conditioning system if you are on the same plane as someone infected with Ebola. If someone infected with Ebola has travelled by plane, the health authorities will trace the passengers who sat near the infected person, because they may have been in contact with bodily fluids from the infected person.

Do I need to take special precautions when I return from a country with an outbreak?

If you are healthy and have no signs of disease, you do not need to take precautions. It is not possible to take blood samples from healthy people to see if they have been in contact with the virus.

What should I do if I get sick after returning from a country with an outbreak?

If you come from one of the countries with an Ebola outbreak and develop symptoms after arriving in Norway, call 113 and say where you have been - do not go to your doctor or to hospital.

I'm expecting a visit from someone from one of the countries with outbreaks. Do I need to take special precautions?

If they are healthy and show no signs of disease, you do not need to take any precautions. There is no reason to avoid people who have been to the outbreak areas and they do not need to be tested or isolated, as long as they have not been in contact with someone who is sick. If you receive a visit from someone who has been to one of the countries with an Ebola outbreak and they develop symptoms after they arrive, call 113 - do not take them to the doctor or to hospital.

What are the preparedness measures in Norway in the event of an Ebola case in Norway?

If a case of Ebola is detected in Norway in someone who has stayed in an outbreak area, the person will be quickly followed up. There is little risk that the disease will spread further in this country. Norway has good preparedness to handle such a situation.

I am travelling to a country with an Ebola outbreak. How can I protect myself?

In the event of an outbreak of the Ebola virus, there is very little risk of infection to tourists or others who stay in the country without being in close contact with sick people.

People travelling to an area with outbreaks should avoid: 

  • contact with sick people 
  • participation in funeral rituals that include direct contact with the deceased if it is suspected/confirmed that the deceased had Ebola
  • close contact with wild animals (including monkeys, antelopes, rodents and bats) 
  • caves and other typical bat habitats 
  • consumption of bush meat, i.e. meat from wild animals killed by hunting

It is always important to have good hand hygiene when travelling abroad to avoid infection.

Is it safe to use the same toilet as an Ebola patient?

There would be some risk of transmission if faeces, urine, blood or other bodily fluids from the Ebola patient are visible on the toilet and they come into contact with mucous membranes or skin wounds.

Can Ebola be transmitted if a patient has touched an object?

This is highly unlikely, as long as you do not get visible bodily fluids such as blood or vomit from an Ebola patient into the mouth, nose, eyes or skin wounds. In laboratory studies, Ebola can survive for several hours on surfaces at room temperature, but the virus has not been proven to be contagious on surfaces outside a laboratory.

History

30.09.2022: Scientifically reviewed and updated