The World Health Organization declared the Ebola outbreak in West Africa a public health emergency of international concern, the first such declaration for a viral haemorrhagic fever.
The outbreak, first detected in southeastern Guinea, spread through Liberia and Sierra Leone, overwhelming health systems with few isolation beds and limited protective equipment. Health workers accounted for a significant share of infections and deaths.
Nigeria contained a separate introduction in Lagos through rapid contact tracing, an intervention widely studied afterwards. The epidemic ultimately killed more than eleven thousand people and accelerated work on an effective vaccine.
