Mali is the latest West African country to go on alert against the Ebola virus, after three cases were reported close to the border with Guinea where 86 people have died. Another six people have died in Liberia, while Sierra Leone has also reported cases.
Senegal has now closed its border with Guinea, and controls are being imposed on people entering Mali’s capital, Bamako. The virus first appeared in Guinea's remote south-eastern region of Nzerekore, where most of the deaths have happened, but it was not confirmed as Ebola for six weeks, and it has now reached the capital, Conarky.
This is the first known outbreak of the disease in Guinea. Most recent cases have appeared in Uganda and the Democratic Republic of the Congo, and a sign of the alarm it is causing is that Saudi Arabia has suspended visas for Muslim pilgrims from Guinea and Liberia.
The virus is spread easily and kills 25-90% of those it infects. Just as with AIDS when it first appeared, there is no vaccine and no cure. The deadliest outbreak so far came in Congo (then Zaire) in 1976 (pictured), when 280 people died - about 88% of those infected.