Paris (AFP)

Ebola, declared Wednesday as a global health "emergency" by the WHO because of the ongoing epidemic in the DRC, is a formidable virus for humans, its epidemics have made a total of about 15,000 deaths since 1976.

- Where does the virus come from? -

The Ebola virus was identified for the first time in 1976 in the Democratic Republic of Congo (DRC, Zaire at the time). This filovirus virus (filovirus) is named after a river in the north of the country, near which the first outbreak erupted.

Five separate "subtypes" of Ebola have since been reported: Zaire, Sudan, Bundibugyo, Reston and Taï Forest. The first three are responsible for major epidemics on the African continent.

- How is it transmitted? -

The virus circulates among fruit-eating bats, considered as the natural host of Ebola but they do not develop the disease.

Other mammals such as great apes, antelopes or porcupines can convey it and transmit it to humans.

During an epidemic, Ebola is transmitted between humans through direct and close contact. A healthy person is contaminated by the "bodily fluids" of a sick person: blood, vomit, feces ...

Unlike the flu, this virus can not be transmitted by air. Ebola is less infectious than many other viral diseases.

But this virus is formidable because of its very high "fatality rate": it kills on average about half of the people it reaches, according to WHO.

- What symptoms? -

After an incubation period of 2 to 21 days (averaging around five days), Ebola is manifested by a sudden fever, with severe weakness, muscle and joint pain, headache and throat and, in some cases cases, hemorrhages.

Sequelae have been common among survivors: arthritis, vision problems, eye inflammation and hearing problems.

- What treatments? -

There is currently no vaccine or marketed treatment for Ebola, but several leads are being tested.

An experimental vaccine was developed as a result of the devastating Ebola outbreak that hit West Africa between late 2013 and 2016, causing more than 11,300 deaths.

A large-scale trial conducted by WHO in Guinea in 2015 showed that it was highly protective, but only against one of the virus strains.

The same vaccine is currently used in a targeted vaccination campaign in the DRC where an epidemic has been raging since mid-2018.

- The worst epidemic between 2013 and 2016 -

Part of southern Guinea in December 2013, the most violent epidemic in history had made until January 2016 more than 11,300 deaths for about 29,000 cases, according to WHO. Victims were more than 99 per cent concentrated in Liberia, Sierra Leone and Guinea.

The current epidemic in the DRC started on August 1, 2018 in the province of North Kivu before spreading. Two cases were recorded in June 2019 in Uganda and a first case in July in the country's second largest city, Goma.

The latest WHO report for this epidemic reports 1,676 deaths for 2,512 cases. This is the tenth epidemic that affects Congolese soil and the second most serious in Africa after that of 2013-2016 in West Africa.

© 2019 AFP