A volunteer health worker practises using a personal protective equipment suit at an Ebola virus treatment center in Liberia. James Giahyue / Reuters

Global health authorities are struggling to contain the world's worst Ebola epidemic since the disease was identified in 1976. The virus has killed more than 4,500 people.

Here is a timeline of the outbreak, and how China and the world have responded.

March 22: Guinea confirms a previously unidentified hemorrhagic fever, which killed more than 50 people, is Ebola.

March 30: Liberia reports two Ebola cases; suspected cases reported in Sierra Leone.

April: China announces 1 million yuan ($160,000) aid package for West Africa, mostly for disease prevention, control and treatment in Guinea, Liberia, Sierra Leone and Guinea-Bissau.

April 1: Medical charity Medecins Sans Frontieres warns the epidemic's spread is "unprecedented". A World Health Organization spokesman calls it "relatively small still".

April 4: Mob attacks Ebola treatment center in Guinea. Healthcare workers there and in Sierra Leone and Liberia face hostility from fearful, suspicious people.

May 26: WHO confirms first Ebola deaths in Sierra Leone.

June 17: Liberia reports Ebola in its capital, Monrovia.

June 23: With deaths above 350, making the West African outbreak the worst on record, MSF says it is "out of control" and calls for massive resources.

July 25: Nigeria confirms its first Ebola case, a man who died in Lagos after traveling from Monrovia.

July 29: Dr Sheik Umar Khan, who was leading Sierra Leone's fight against the epidemic, dies of Ebola.

July 30: Liberia shuts schools, quarantines the worst-affected communities, using troops for enforcement.

Aug 1: Precautionary measures (body temperature testing) put in-place in the city of Guangzhou to stop the potential spread of the Ebola virus in China. More than 1,000 people from Africa arrive at the Baiyun Airport in Guangzhou every day.

Aug 2: A US missionary physician infected with Ebola in Liberia is flown to Atlanta in the United States for treatment.

Aug 5: A second US missionary infected with Ebola is flown from Liberia to Atlanta for treatment.

Aug 7: China announces a humanitarian aid package worth 30 million yuan for Liberia, Sierra Leone and Guinea. The package includes personal protective equipment, patient monitors, sprays and medicines.

Aug 8: WHO declares Ebola "international public health emergency."

Cao Guang, a member of a 38 strong Chinese medical assistance team working with Ebola sufferers in Guinea, is cleared of infection after 21 days in quarantine. The team was on the latest rotation of a goodwill medical mission that has seen Chinese medicos stationed in Guinea since the late 1960s. The team leader confirms the medical workers will not be evacuated, but will instead stay to help fight Ebola.

Aug 11: Shipment of Chinese medical supplies arrives in Liberia.

Aug 12: WHO says death toll tops 1,000, approves use of unproven drugs or vaccines.

A Spanish priest with Ebola dies in Madrid hospital.

Aug 15: Medecins Sans Frontieres says epidemic will take about six months to control.

Aug 16: UN Secretary-General Ban Ki-moon praises China's timely assistance to Africa in the fight against Ebola.

Aug 19: Liberian President Ellen Johnson-Sirleaf lauds medical aid from China.

Aug 20: Security forces in Monrovia fire shots, tear gas to disperse crowd trying to break out of quarantine, killing 10.

Aug 21: Two US missionary aid workers treated in Atlanta discharged from hospital Aug 19 and 21 free of the virus.

Aug 24: Democratic Republic of Congo declares Ebola outbreak, believed separate from West Africa epidemic.

Aug 28: WHO puts death toll above 1,550, warns outbreak could infect more than 20,000.

Aug 29: Senegal reports first confirmed Ebola case.

Sept 2: Medecins Sans Frontieres president tells UN the world is losing battle to contain Ebola, criticizes "global inaction".

Sept 3: Deaths top 1,900. Officials say close to 400 deaths in past week.

Third US missionary doctor infected with Ebola is flown from Liberia for treatment in Omaha, Nebraska.