An automated computer program run by experts in Boston may have detected Ebola almost nine days before the World Health Organisation (WHO) formally announced the epidemic.
Using algorithms to sort through data on social media sites, local news reports, government websites, infectious disease doctors' social networks and other sources, the online tool HealthMap warned of a "mystery hemorrhagic fever" appearing in forested areas of south-east Guinea.
HealthMap is operated by a group of 45 researchers, epidemiologists and software developers at Boston Children's Hospital. It generates information that includes locations of specific outbreaks and tracks new cases and deaths.
Sophisticated software filters irrelevant data, classifies the relevant information, identifies diseases and maps their locations with the help of experts.
"It shows some of these informal sources are helping paint a picture of what's happening that's useful to these public health agencies," HealthMap co-founder John Brownstein said.
Ebola spread mapped
Nearly 1,000 people have died since the Ebola outbreak was announced on 25 March. Healthcare workers treating have been infected, and travellers from East Africa have been taking the virus along with them, leading to outbreaks and scares in many countries.
So far only one death from Ebola has been confirmed outside of East Africa, that of a man in Saudi Arabia who had recently returned from East Africa. However, 21 Thai tourists are suspected of bringing the disease back home to Thailand, and there have been other scares in Hong Kong, America, and the United Kingdom.
The map below shows the countries have been invaded by the lethal virus. Red areas indicate where Ebola has killed. Orange show where patients with actual or suspected cases of Ebola are being treated. Yellow marks where Ebola was thought to have been present, but was proved otherwise.