The face of Ebola: changing frequency of haemorrhage in the West African compared with Eastern-Central African outbreaks
The West-African (WA) Zaire Ebola virus outbreak had a significantly higher number of deaths compared to the outbreak in Easter-Central African (ECA) outbreaks. The increased survival rates are explained in the context of great humanitarian efforts. Previous work also suggests that the long human-to-human transmission cycle occurred in WA, which gave rise to human adaptation and consequent immune escape. This systematic review offers support for the human adaptation hypothesis by providing data that indicates a smaller proportion of Ebola virus patients with haemorrhage in the WA outbreaks compared to the ECA outbreaks.
This systematic review compared the relative frequencies of three typical Ebola virus haemorrhagic symptoms: conjunctival, nasal, and gingival bleedings in the Eastern-Central African and West-African outbreaks. Fifteen studies were included, of which 10 related to ECA and 5 to WA. 4,867 patients were identified with conjunctival bleeding, 3,859 with nasal bleeding, and 4,278 with gingival bleeding.