Ebola virus disease

Ebola virus disease, known as EVD or Ebola for short, is a potentially fatal infectious disease. The disease is caused by the Ebola virus. There are various strains or species of Ebola virus, known as Zaire, Sudan, Tai Forest, Bundibugyo and Reston.

To date, outbreaks of Ebola have only ever occurred in sub-Saharan Africa.

Ebola is mainly transmitted from person to person. However, it can also be transmitted via contact with infected animals, animal products and objects.

There are two effective vaccines against the Zaire strain of the Ebola virus, as well as two types of medication for targeted treatment.

The initial symptoms are non-specific and resemble those of the flu – high temperature, fatigue, aching limbs and a general sense of feeling unwell. Pain in the upper abdomen, nausea, vomiting, loss of appetite and diarrhea may develop after several days.

Additional symptoms are also possible as the disease progresses. These include:

• headache and chest pain
• joint and muscle pain
• skin rash
• difficulty swallowing
• neurological problems, such as impaired perception, unsteadiness or seizures
• slowed heartbeat
• internal and external bleeding
• shortness of breath and breathing difficulties

Post-Ebola syndrome

Some patients can experience health issues even after recovering from an infection. Such cases are termed post-Ebola syndrome. Symptoms consist of fatigue, sleepiness, muscle and joint pain, body aches and memory loss. Problems with hearing and vision, as well as depression and anxiety disorders may also occur.

The Ebola virus is found in nature in wild animals, for example, in certain species of fruit bats. When these animals are hunted, the virus comes into contact with humans. The Ebola virus is transmitted from person to person via bodily fluids.

Transmission from person to person

Transmission occurs through direct physical contact with Ebola patients or the bodies of people who have died of Ebola virus disease. Direct contact with bodily fluids such as blood, saliva, sweat, urine, feces or vomit is particularly risky.

People infected with the Ebola virus are only contagious once they display symptoms. An average of 8 to 9 days pass between infection and the onset of symptoms although this period can range from 2 days to 3 weeks. The more severe the health issues become as the disease progresses, the greater the risk of contagion.

Patients are classed as no longer contagious several days after their symptoms have disappeared. However, the virus can still be transmitted by sperm during sexual intercourse for several months.

Transmission via objects

For a certain time, the virus can also be transmitted via objects that have come into contact with infectious liquids. These can include needles, surgical equipment, clothing and bed linen.

Transmission via animals

The Ebola virus can also be transmitted to humans through contact with infected animals or animal products. Specifically, this can occur in affected areas during hunting or slaughter as well as when preparing and eating the meat of infected wild animals (“bushmeat”). This is also likely to trigger an Ebola outbreak.

Anyone who has not been vaccinated has a very high risk of infection if they have unprotected, direct contact with:

• people infected with Ebola
• the bodies of people who have died from Ebola
• the bodily fluids of people infected with Ebola or who have already died from the disease, including blood, saliva, sweat, urine, feces or vomit

The high risk of fatality means that the strictest safety precautions apply when dealing with patients and the deceased. The mortality rate is around 30 to 90 percent.

To date, Ebola outbreaks have only ever occurred in sub-Saharan Africa. There have been recurring outbreaks, both large and small, in Central Africa since 1976. The countries that have been most affected are the Democratic Republic of the Congo, Gabon, the Republic of the Congo, present-day South Sudan and Uganda.

The major outbreak from 2014 to 2016, on the other hand, affected the West African countries of Guinea, Sierra Leone and Liberia in particular. This outbreak also resulted in cases in Mali and Nigeria. It was by far the largest outbreak of Ebola virus disease that had been seen up to that point.

During this Ebola epidemic, a number of infected individuals were also recorded in the USA and Europe. However, the disease did not become widespread there.

An infection with Ebola progresses through various phases:

Early fever phase

About 8 to 9 days on average after infection, non-specific symptoms of Ebola begin, such as high temperature, headache, aching limbs and extreme fatigue. However, symptoms may occur within a period ranging from just 2 days to 3 weeks following infection.

Gastrointestinal phase

A few days after the onset of the disease, the additional symptoms of nausea, vomiting, diarrhea and upper abdominal pain also appear.

Some patients also experience conjunctivitis, pharyngitis, hiccups, confusion (delirium) or a rash.

As the disease progresses, both external and internal bleeding may occur. This particularly affects the digestive tract, lungs and gums.

Improvement or deterioration phase

Whereas some patients start to slowly improve in the second phase, others experience a deterioration in their condition. If this occurs, loss of fluids, hemorrhages and organ failure often result in death. Between 30 and 90 percent of people infected with Ebola will die as a result.

Ebola virus disease can be caused by various species of Ebola virus. At present, two effective vaccines are available against just one of these strains, i.e., the Zaire Ebola virus. Both vaccines have been approved in Germany.

One of the vaccines can also be used following contact with an infected person. If administered in time, it offers a certain degree of protection for contacts.

For people who have not been vaccinated, it is important to avoid contact with infected people and with the bodies of those who have died from the virus and their bodily fluids. Healthcare professionals can protect themselves against infection by wearing protective clothing and following hygiene measures.

Blood or other bodily fluids are analyzed in the laboratory to diagnose the disease. Molecular genetic testing (PCR testing) can detect components of the Ebola virus.

In certain cases, it may not be possible to detect the virus until the third day after symptoms begin. Therefore, if the result of an early test is negative, it may be necessary to repeat the test again later.

In the USA, two types of medication have been approved for treating Ebola virus disease, although these are only for infections with the Zaire strain. Both treatments consist of monoclonal antibodies. These are special defensive substances that are manufactured in a lab. They can detect pathogens such as the Ebola virus and render them harmless. If administered in time, this treatment can cure approximately 90 percent of patients. The treatments have not yet been approved in Germany.

If medication is unavailable or if the disease has been caused by a different species of Ebola virus, doctors can only treat the symptoms. It is particularly important to compensate for the loss of fluids, sugar and electrolytes. Patients are therefore given an infusion of saline and sugar solutions.