The origin, symptoms and how it spreads

Ugandan health authorities have declared an outbreak of Ebola virus disease. Ebola outbreaks periodically appear in several African countries, including the Democratic Republic of Congo (DRC). Public health expert Yap Boum, who has been involved in managing Ebola outbreaks in the past, answers some key questions about Ebola’s history, treatment and how to stay safe.

What are the origins of the virus?

Ebola is an old and deadly disease that was discovered in 1976 near the Ebola River in northern DRC. The virus was named after the river. It was discovered by scientists including Jean-Jacques Muyembe – a Congolese microbiologist and director general of the DRC’s National Institute for Biomedical Research – and researchers from the Institute of Tropical Medicine, including Stefaan Pattyn, Guido van der Green and Peter Piot.

Professor Muyembe was called to the village of Yambuku in northern Zaire (now DRC) where a mysterious illness had broken out. He took a sample and sent it to the laboratory of the Institute of Tropical Medicine in Belgium, where the virus was isolated.

Since then, five strains of Ebola virus have been identified, four of which are known to cause disease in humans: Ebola virus (zaire ebolavirus); Sudan Virus (Sudan Ebolavirus); Taï Forest Virus (Taï Forest Ebolavirus, formerly Côte d’Ivoire Ebola virus); and Bundibugyo virus (ebola virus Bundibugyo).

It is a zoonotic disease (transmitted by animals) although the natural reservoir host of the Ebola virus remains unknown. However, bats are the most likely reservoir.

What are the symptoms of Ebola?

While signs and symptoms can appear between 2 and 21 days after contact with the virus, they usually appear between 8 and 10 days.

They are quite similar to many tropical diseases, including malaria and typhoid fever, with which they share symptoms such as:

  • fever
  • aches and pains, such as severe headaches and muscle and joint pain
  • weakness and fatigue
  • sore throat
  • loss of appetite
  • abdominal pain
  • diarrhea and vomiting
  • unexplained bleeding, bleeding or bruising.

The main differences appear in the later stages of infection. These symptoms can include red eyes, rashes, and hiccups.

Can it be treated?

Ebola virus disease can now be treated. The PALM clinical trial – implemented between 2018 and 2020 in the DRC – evaluated four drug candidates. Two of them – Inmazeb and Ebanga – were approved by the US Food and Drug Administration in October and December 2020 to treat Ebola virus disease caused by the Ebola virus. They are made available to patients by the World Health Organization (WHO) during Ebola outbreaks and are not commercially available.

Inmazeb is a combination of three monoclonal antibodies and Ebanga is a single monoclonal antibody. Monoclonal antibodies (often abbreviated as mAb) are proteins produced in a laboratory or other manufacturing facility that act like natural antibodies to prevent a germ such as a virus from replicating after infecting a person.

Ebanga was isolated from a human survivor of the 1995 Ebola outbreak in Kikwit, DRC who maintained circulating antibodies to Ebola virus for more than a decade after infection.

Without treatment, the average case fatality rate is around 50%. But it has varied from 25% to 90% in past outbreaks.

Can it be avoided?

People can be vaccinated against one strain, the Zaire Ebola virus. It became a preventable disease following the validation of a vaccine candidate during the That’s enough Ebola clinical trial in 2015 in Guinea. The Ebola rVSV-ZEBOV vaccine (called Ervebo®) was approved by the United States Food and Drug Administration in December 2019. This vaccine is given as a single-dose vaccine and has been shown to be safe and protective with efficacy reported 100%.

Although it has not yet been approved by the United States Food and Drug Administration, Johnson & Johnson has a two-dose vaccine against the Zaire strain which was used in emergency in 2019 during an epidemic of Ebola in the DRC. This vaccine requires an initial dose and a “booster” dose 56 days later and could be made available by the WHO during epidemics.

How can you protect yourself?

Ebola is a highly transmissible disease but, in addition to vaccination against the Zaire strain, its spread can be prevented through behavioral measures.

People should avoid contact with blood and body fluids – such as urine, feces, saliva, sweat, vomit, breast milk, amniotic fluid, semen and vaginal secretions – of people sick. People should also avoid contact with personal items that may contain traces of these fluids.

Previously infected people may still carry the disease in their semen.

Because it is a zoonotic disease – that is, transmitted from animals to humans – people should avoid contact with bats, forest antelopes, primates not humans (such as monkeys and chimpanzees) and wild meat and blood, especially in endemic areas.

Finally, burial or funeral practices that involve touching the body of someone who may have died of Ebola should be avoided. Experience in West Africa shows that these funeral practices are among the super-spreaders of the Ebola virus.

Ebola virus disease is a fatal disease that is preventable and curable. The next step is the local production of diagnostics, vaccines and medicines to ensure that endemic countries control their own stock and can make them available to their population. Africa can no longer be left behind when it comes to diagnosis, vaccines and treatment, as it has been during the COVID pandemic and monkeypox outbreaks.

Yap Boum, professor at the faculty of medicine, Mbarara University of Science and Technology

This article is republished from The Conversation under a Creative Commons license.