Here are the main epidemics which have broken out over the past century, after the World Health Organisation on August 08 designated the killer Ebola ravaging parts of west Africa an international health emergency:
-- SPANISH FLU: between 1918 and 1919 it affected a large part of the world's population, as it emerged from the ravages of World War I. It killed at least 40 million people, according to the WHO, with those suffering wartime shortages worst hit.
-- AIDS: By far the most deadly epidemic of modern times: according to UNAIDS some 78 million people around the world have been infected by HIV since 1981, of whom 39 million have died of AIDS.
-- SEVERE ACUTE RESPIRATORY SYNDROME (SARS): It first emerged in Guangdong in southern China in November 2002 before sparking a crisis in 2003, affected 8,000 people around the world, killing more than 800, including nearly 350 in China.
The deadly H5N1 strain of Bird flu has killed more than 400 people, mainly in Southeast Asia, since it first appeared in 2003.
• H1N1: Uncovered in Mexico and the United States in March, 2009 and nicknamed "Swine Flu", the pandemic alert was launched on June 11, 2009 and lifted on August 10, 2010. Was not as deadly as first thought and vaccines were made in the space of several months. The WHO puts the death toll at 18,500 in 214 countries. Annual Influenza epidemics cause between three and five million serious cases every year, of which 250,000 and 500,000 die of the virus, according to the WHO.