People walk past a wall bearing information about the symptoms of Ebola in Monrovia on September 25, 2014. World leaders were asked to pledge urgently needed aid to battle Ebola in West Africa as Sierra Leone quarantined one million people in a desperate bid to beat back the deadly virus. US President Barack Obama warned that not enough was being done to tackle the crisis that has left close to 3,000 dead and is spreading at an alarming pace. AFP PHOTO / PASCAL GUYOT