Ebola haemorrhagic fever

The Ebola virus belongs to the Filoviridae family (filovirus) and is comprised of five distinct species: Zaïre, Sudan, Côte d’Ivoire, Bundibugyo and Reston.

Zaïre, Sudan and Bundibugyo species have been associated with large Ebola haemorrhagic fever (EHF) outbreaks in Africa with high case fatality ratio (25–90%) while Côte d’Ivoire and Reston have not. Reston species can infect humans but no serious illness or death in humans have been reported to date.

Human infection with the Ebola Reston subtype, found in the Western Pacific, has only caused asymptomatic illness, meaning that those who contract the disease do not experience clinical illness. The natural reservoir of the Ebola virus seems to reside in the rain forests of the African continent and in areas of the Western Pacific. There is evidence that bats are involved, but much work remains to be done to definitively describe the the natural transmission cycle.

Transmission

• The Ebola virus is transmitted by direct contact with the blood, secretions, organs or other body fluids of infected persons.
• Burial ceremonies where mourners have direct contact with the body of the deceased person can play a significant role in the transmission of Ebola.
• The infection of human cases with Ebola virus through the handling of infected chimpanzees, gorillas, and forest antelopes – both dead and alive – has been documented in Côte d'Ivoire, the Republic of Congo and Gabon. The transmission of the Ebola Reston strain through the handling of cynomolgus monkeys has also been reported.
• Health care workers have frequently been infected while treating Ebola patients, through close contact without correct infection control precautions and adequate barrier nursing procedures.