Research for infection protection

Ebola

What is Ebola?

Ebola, also known as Ebola haemorrhagic fever, is a life-threatening viral haemorrhagic fever disease. The first Ebola outbreaks were recorded in 1976 and, to date, the disease has exclusively affected sub-Saharan Africa. However, individual cases have been confirmed whereby those infected travelled to other countries, fell ill there and in some cases even transmitted the disease to other people. However, there has never been an epidemic to report outside of Africa. The Robert Koch Institute (RKI) reports that the risk of Ebola being brought to and spreading in Germany is considered to be very low.

The West African countries of Guinea, Sierra Leone and Liberia were most affected by the 2014/2015 Ebola epidemic, in which more than 28,000 people contracted the disease, and more than 11,000 died. A new aspect of this outbreak was that, for the first time, it targeted not only smaller, mainly rural regions, but almost all provinces of the countries as well as large cities. The epidemic in West Africa peaked in autumn 2014 and eased in the course of 2015, which is why the World Health Organization (WHO) declared it over in spring 2016. Since the pathogen that causes Ebola can remain in the body for some time, it is impossible to prevent smaller outbreaks, such as those reported in the years following the major epidemic in 2014/2015, with certainty. The outbreaks in Guinea and the Democratic Republic of Congo are currently (as of March 2021) a major cause for concern. The outbreak in Guinea is quite shocking since it may have been traced back to survivors of the 2014/2015 epidemic. To avoid further stigmatisation of those who have recovered, it is crucial to provide reasonable clarification.

 

Which pathogen causes Ebola?

Ebola is triggered by an infection with Ebolaviruses which can be classified into five species, four of which are human pathogenic. The virus is primarily transmitted from one person to another through direct contact with body fluids such as blood, stool, urine, vomit, saliva, sweat or seminal fluid. For now, the airborne spread of the virus via aerosols is not possible. However, the viruses can survive for a specific period on contaminated objects, such as needles, surgical instruments, clothing or bed linen; this way, it carries on spreading. Contact with infected animals or infectious animal products may result in transmission of the virus, too. It is believed that infected people first become contagious when symptoms appear, and the more pronounced the symptoms, the more contagious they become. In rare cases, the virus can also be present in survivors of an Ebola infection and reintroduced into circulation, e.g., via seminal fluid during unprotected sexual intercourse, even after a long period.

Flying foxes or bats probably serve as wildlife reservoirs for Ebola viruses.

 

Who can contract Ebola?

The disease mainly affects people who have not been vaccinated against Ebola and have had direct contact with patients or deceased persons or their body fluids. Due to the transmission routes, people who care for the sick without sufficient protection (e.g., medical staff or caring relatives), come close to deceased persons (e.g., funeral staff) or work with infectious material (e.g., laboratory staff) are particularly at risk of becoming infected. Since the virus has its natural reservoir in wild animals, people who come into contact with infected animals or infectious animal products can also become infected.

The extent to which the survivors of the infection are immune to the virus has not yet been adequately clarified. Presently, it is assumed that a certain level of protection against a new infection with the same species of the Ebola virus persists for several years.  

 

What symptoms are associated with Ebola?

Ebola-infected people usually develop the first symptoms after an incubation period of 2 to 21 days (on average, 6 to 10 days), which are initially mild and correspond to those of a flu. In addition to fever and aching joints, the symptoms include general discomfort, fatigue, headache and sore throat. Later, diarrhoea, vomiting and skin rash usually develop; increased organ infection can lead to liver or kidney complication. Some patients also show an increased tendency to bleed (e.g., from mucous membranes and body orifices), which actually gives the term "haemorrhagic fever" its name but occurs less frequently than originally assumed.

Ebola’s mortality rate is quite high, as it stands at 25 to 90%. On average, one in two persons dies of it. The so-called Zaire Ebola virus is considered the deadliest strain.

Since the virus can persist in various organ systems, e.g., the nervous system, long-term side effects of the disease can appear.

 

How is Ebola treated?

In most cases, Ebola is primarily treated symptomatically, i.e., the ill people are mainly treated against increasing dehydration by means of fluid intake. However, there are various treatment approaches currently being researched. Since 2020, there are also two antibody drugs approved by the Food and Drug Administration (FDA) against infections of the Zaire Ebola virus.


How can Ebola be prevented?

Since 2020, a highly effective vaccine against the Zaire Ebola virus has been available and has already been administered to hundreds of thousands of people in endangered regions. This can also be administered at an early stage after exposure, which is why so-called ring vaccinations of people in contact with an infected person make sense to prevent further spread.

A second vaccine relies on a two-stage administration at an interval of several weeks and is also available as of recently. However, due to the administration interval, this is not suitable for short-term control, but only for long-term containment or prevention of outbreaks.

Besides vaccination, non-pharmacological measures continue to play a major role in combating the epidemic. Affected countries and neighbouring countries need to respond quickly and refer to their experience from past epidemics. Among other things, this includes surveillance and contact tracing, good laboratory diagnostics, safe burials and community engagement by raising awareness of risks and protective measures.


Sources:
Ärztezeitung. WHO concerned about Ebola outbreaks. Published: 15 March 2021
Patel PR, Schah S. Ebola Virus. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Published:2021
Robert Koch-Institut. Answers to frequently asked questions about Ebola fever. Published: 29 July 2020
Robert Koch-Institut. Information on the Ebola fever outbreak in West Africa 2014/2015. Published: 30 March 2016
Robert Koch-Institut. Information on current Ebola fever outbreaks in Guinea and the Democratic Republic of Congo. Published: 12 March 2021
World Health Organization. Fact Sheet Ebola virus disease. Published: 23 February 2021