International agencies and governments are struggling to contain the world's worst epidemic of the Ebola hemorrhagic virus, which has killed over 1,900 people in West Africa.
Here is a timeline of the main developments in the outbreak.
March 22 - Guinea confirms that a previously unidentified hemorrhagic fever, which killed over 50 people in its southeast Forest Region, is the Ebola virus. One study traces the suspected original source to a 2-year-old boy in the town of Gueckedou. Cases are also reported in the capital, Conakry.
March 30 - Liberia reports two Ebola cases; suspected cases are also reported in Sierra Leone.
April 1 - Noting the spread, medical charity Medecins Sans Frontieres (MSF) warns it is "unprecedented", but a World Health Organization (WHO) spokesman calls it "relatively small still".
April 4 - An angry mob attacks an Ebola treatment center in southeast Guinea. Health workers in Guinea, Sierra Leone and Liberia face increasing hostility from fearful and suspicious local people, many of whom refuse to believe the disease exists.
May 26 - WHO confirms the first deaths in Sierra Leone.
June 17 - Liberia says disease reaches its capital Monrovia.
June 23 - With the death toll surging above 350, making the West African outbreak the worst Ebola epidemic ever recorded, MSF says the outbreak is "out of control" and calls for massive resources.
July 25 - Nigeria, Africa's biggest economy, confirms its first Ebola case, a Liberian-American man who died in the commercial hub, Lagos, after traveling from Monrovia.
July 29 - Dr. Sheik Umar Khan, who was leading Sierra Leone's fight against the epidemic, dies of the virus.
July 30 - Liberia shuts schools and orders the quarantining of the worst-affected communities, using troops to enforce it.
July 31 - The U.S. Peace Corps withdraws all volunteers from Liberia, Sierra Leone and Guinea, citing Ebola risks.
Aug 2 - An American missionary aid worker infected with Ebola in Liberia, Dr. Kent Brantly, is flown to Atlanta in the United States for treatment at Emory University Hospital.
Aug 4 - The World Bank announces up to $200 million in emergency assistance to help Liberia, Sierra Leone and Guinea.
Aug 5 - Second U.S. missionary infected with Ebola, Nancy Writebol, is flown from Liberia to Atlanta hospital.
Aug 8 - WHO declares Ebola an "international public health emergency" but stops short of calling for a ban on international trade or travel.
Aug 12 - WHO says death toll from outbreak rises above 1,000, approves use of unproven drugs or vaccines.
Spanish priest infected with Ebola dies in Madrid hospital.
Aug 14 - WHO says reports of Ebola deaths and cases from the field "vastly underestimate" the scale of the outbreak.
Aug 15 - MSF compares the West African Ebola outbreak to "wartime," says it will take about six months to control.
Aug 20 - Liberian security forces in Monrovia fire live rounds and tear gas to disperse crowd trying to break out of Ebola quarantine. One teenager later dies of gunshot wounds.
Aug 21 - The two American missionary aid workers treated in Atlanta are released from the hospital free of the virus. They received an experimental therapy called ZMapp.
Aug 24 - Democratic Republic of Congo declares an Ebola outbreak in its northern Equateur province, apparently separate from the larger West African outbreak.
Infected British medical worker flown home for treatment from Sierra Leone.
Aug 28 - WHO says death toll climbs above 1,550, warns outbreak could infect more than 20,000 people. The U.N. health agency announces a strategic plan to fight the epidemic, says $490 million needed over the next six months.
Aug 29 - Senegal reports its first confirmed Ebola case.
Aug 30 - World Food Program says it needs $70 million to feed 1.3 million people at risk in Ebola-quarantined areas.
Sept 2 - MSF President Joanne Liu tells United Nations members the world is "losing the battle" to contain the Ebola outbreak and slams "a global coalition of inaction".
The U.N. Food and Agriculture Organization (FAO) says the Ebola epidemic has endangered harvests and sent food prices soaring in West Africa. FAO warns the problem will intensify in coming months.
Sept 3 - Pace of the epidemic accelerates, with death toll topping 1,900. Officials say there were close to 400 deaths in the past week.
The United Nations says $600 million in supplies will be needed to fight the outbreak in West Africa, and Guinea warns the virus has penetrated a new part of that country.
An experimental Ebola vaccine that Canada offered to WHO for use in Africa is stuck in the lab that developed it because officials cannot figure out how to transport it without endangering its viability.
Officials announce human safety trials for two vaccines and a U.S. government contract to accelerate testing of the experimental ZMapp treatment.
A third U.S. missionary infected with Ebola is identified as Dr. Rick Sacra, a 51-year-old Boston physician. He is flown out of Liberia for treatment in the United States.