A man walks by a sign that reads "Ebola is real" in Monrovia, Liberia, October 21, 2014. (Reuters)
Global health authorities are struggling to contain the worst Ebola epidemic since the disease was identified in 1976.
Here is a timeline of the outbreak:March 22: Guinea confirms hemorrhagic fever that killed more than 50 people is Ebola.
March 30: Liberia reports two cases; Ebola suspected in Sierra Leone.
April 1: Medical charity Medicins Sans Frontieres (MSF) warns Ebola's spread is "unprecedented."
May 26: WHO confirms first Ebola deaths in Sierra Leone.
June 23: More than 350 deaths make West Africa outbreak worst on record; MSF calls for massive resources.
July 25: Nigeria confirms its first Ebola case.
July 30: Liberia shuts schools, quarantines worst-affected communities, using troops for enforcement.
Aug. 2: US missionary doctor infected with Ebola in Liberia is flown to Atlanta in United States for treatment.
Aug. 5: Second US missionary with Ebola is flown from Liberia to Atlanta.
Aug. 8: WHO declares epidemic an "international public health emergency."
Aug. 12: Deaths top 1,000; WHO approves use of unproven drugs or vaccines.
Spanish priest with Ebola dies in Madrid hospital.
Aug. 21: Two US missionary workers released from Atlanta hospital August 19 and 21 free of virus.
Aug. 24: Democratic Republic of Congo declares Ebola outbreak; it is believed separate from West Africa epidemic.
Infected British medical worker flown home from Sierra Leone for treatment.
Aug. 28: WHO puts deaths above 1,550, warns 20,000 plus could be infected.
Aug. 29: Senegal reports first confirmed Ebola case.
Sept. 3: Epidemic accelerates; deaths top 1,900 with close to 400 in past week.
Third US missionary doctor with Ebola flown from Liberia for treatment in Omaha, Nebraska.
Sept. 5: WHO says more than 2,100 dead out of about 4,000 thought to have been infected.
Sept. 8: Britain sending military, humanitarian experts to Sierra Leone to set up treatment center; United States to send field hospital to Liberia to care for health workers.
Fourth Ebola patient will be flown to Atlanta for treatment.
Sept. 9: WHO says at least 2,296 dead out of 4,293 cases in five countries.
Sept. 12: Cuba to send 165 doctors, nurses to Sierra Leone.
Sept. 13: Liberia appeals to US President Barack Obama for aid to fight Ebola.
Sept. 16: United States promises 3,000 military engineers, medical personnel to West Africa to build clinics, train health workers.
WHO says 2,461 dead out of 4,985 infected, doubling death toll in past month.
Sept. 17: MSF says French nurse volunteer in Liberia has Ebola.
Sept. 18: WHO says 2,630 dead out of 5,357 thought infected.
United Nations mission to combat Ebola will deploy staff in Liberia, Guinea, Sierra Leone. Security Council wants travel, border restrictions lifted.
French President Francois Hollande says military hospital will be set up in Guinea.
Sept. 19: Sierra Leone's capital, Freetown, put under three-day lockdown to try to halt Ebola's spread.
Sept. 20: Liberian Thomas Eric Duncan flies from Liberia to Dallas via Brussels and Washington after trying to help woman with Ebola in his home country.
Sept. 22: WHO says outbreak largely contained in Senegal and Nigeria; says Ebola has killed more than 2,811 in West Africa.
Sept. 23: US Centers for Disease Control and Prevention (CDC) estimates between 550,000 and 1.4 million people in West Africa may have Ebola by January.
Sept. 25: Duncan goes to Dallas hospital with fever, stomach pain. He is sent back to apartment where he is staying despite telling nurse he traveled from West Africa.
Sept. 26: WHO says 3,091 dead out of 6,574 probable, suspected and confirmed cases.
Cuba training 296 more doctors, nurses to treat Ebola in West Africa, in addition to 165 preparing to go to Sierra Leone.
Sept. 28: Duncan returns by ambulance to Dallas hospital.
Sept. 30: CDC confirms Duncan has Ebola; first case diagnosed in United States.
Oct. 1: WHO says 3,338 dead out of 7,178 West Africa cases.
Cuba sends 165 doctors, nurses to Sierra Leone.
Oct. 2: Britain pleads for global help to fight Ebola.
NBC News says American freelance cameraman, Ashoka Mukpo, has Ebola; will be flown to United States for treatment.
Oct. 3: WHO: 3,439 dead out of 7,492 suspected, probable and confirmed cases in West Africa and United States, which has one.
Ugandan doctor with Ebola arrives in Frankfurt from Sierra Leone for treatment.
Oct. 4: Nurse in Liberia who was first French national to contract Ebola leaves hospital near Paris free of virus.
Oct. 6: Spanish nurse has Ebola; she treated priest who was repatriated to Madrid and died.
Cameraman Mukpo in Omaha; taken to Nebraska Medical Center.
Oct. 8: Duncan, first person diagnosed with Ebola in United States, dies in Dallas hospital.
United States orders five airports to screen travelers from West Africa for fever.
Oct. 9: WHO revises deaths to 3,865 out of 8,033 cases, says no evidence Ebola is being brought under control in West Africa.
Britain to screen travelers entering country through London's main airports and Eurostar rail link with Europe.
Some lawmakers want United States to ban travelers from West African countries hit hardest by Ebola.
Oct. 10: WHO: 4,033 dead out of 8,399 cases in seven countries. Most fatalities in Liberia, Sierra Leone and Guinea.
Oct. 11: New York's John F. Kennedy International Airport begins screening travelers from three West African countries for Ebola symptoms.
Oct. 12: Dallas nurse Nina Pham has Ebola; first person to contract it in United States. Infected while caring for Duncan.
Oct. 14: At London's Heathrow airport, Britain begins screening travelers from West Africa.
Sudanese U.N. medical official who contracted Ebola in Liberia dies in German hospital.
Oct. 15: Second Texas nurse who treated Duncan has Ebola. Amber Vinson will be treated at Atlanta's Emory University Hospital. She took flight from Cleveland to Dallas/Fort Worth International Airport while running slight fever.
WHO says 4,493 dead out of 8,997 cases, epidemic spreading in West Africa.
Oct. 16: US congressional subcommittee questions health officials about American response to Ebola. National Institutes of Health says nurse Pham will be moved to NIH isolation unit in Bethesda, Maryland, from Dallas.
Oct. 17: WHO says 4,546 dead out of 9,191 cases. Senegal declared free of Ebola. Obama appoints Ebola response coordinator.
Oct. 19: Nigeria declared free of Ebola. Spanish nurse appears to be cured.
Oct. 20: In Texas, 43 people taken off Ebola watch lists. United States issues stricter guidelines for those treating Ebola victims.
Oct. 21: Medicins Sans Frontieres will start trials of experimental Ebola drugs at its West Africa treatment centers in November.
Cuba sends 53 doctors, nurses to Liberia, 38 to Guinea to treat Ebola patients; second group from that country.
As of Oct. 22, travelers to United States from Liberia, Sierra Leone and Guinea must fly into one of five airports for enhanced screening.
Oct. 22: United States will monitor for 21 days anyone entering from three countries at center of epidemic.
NBC cameraman Mukpo leaves Nebraska hospital free of Ebola.
Oct. 23: New York City doctor Craig Spencer, who treated patients in Guinea, tests positive for Ebola.
Mali becomes sixth West African country hit by Ebola.
Oct. 24: Dallas nurse Pham leaves hospital free of Ebola.
New York and New Jersey order quarantine of medical workers returning from Ebola-hit West African countries. Nurse Kaci Hickox tests negative and is quarantined, under protest, for two days in New Jersey. She goes to Maine, where she is ordered isolated in her home. She challenges that order.
Oct. 25: WHO says 4,922 dead out of 10,141 cases.
Illinois orders quarantine of all high-risk travelers returning from Ebola-hit West African countries.
Oct. 26: Florida will monitor for 21 days people returning from Ebola-hit countries, quarantine "high-risk" individuals.
Oct. 27: US Army isolating personnel returning from Ebola missions in West Africa.
Australia becomes first developed country to shut its borders to areas hardest hit by Ebola; bans visas for citizens of Sierra Leone, Liberia and Guinea.
Oct. 28: Dallas nurse Vinson leaves Emory University Hospital free of Ebola.
Oct. 29: Quarantine-like monitoring expanded to all US military personnel returning from West Africa Ebola missions.
California enacts 21-day quarantine of travelers who had contact with Ebola patients.
Oct. 31: Canada stops issuing visas to people from Sierra Leone, Liberia and Guinea.
Nov. 3: Mali thought to be Ebola-free; officials search for 39 people who traveled on buses with child who died from virus.
In Maine, nurse Hickox will not be quarantined.
Nov. 5: WHO revises deaths downward for second week running to 4,818 out of 13,042 cases as of Nov. 2. Says weekly cases rising in Sierra Leone, slowing in Liberia, Guinea is stable.
Obama to ask Congress for $6.2 billion in new fiscal year to fight Ebola, sources say.
China plans to send 1,000 medical workers, experts to West Africa, Xinhua news agency reports.
Australian Prime Minister Tony Abbott says his country will fund treatment clinic in Sierra Leone.
Nov. 7: 4,950 dead out of 13,241 cases in worst-hit West Africa countries.
Dallas declared Ebola-free.
Nov. 11: Mali confirms second Ebola case; locks down clinic.
New York doctor Spencer leaves hospital free of virus.
Nov. 12: 5,147 dead out of 14,068 cases in Guinea, Liberia and Sierra Leone; 13 deaths, 30 cases in five other countries.
Mali's Ebola deaths rise to four; more than 90 quarantined.
US nurses protest over Ebola protection; Sierra Leone health workers strike over pay.
Nov. 13: Mali imposes tougher health checks at border crossings after its second outbreak.
Eighty US troops return to United States from Liberia and begin 21 days monitored isolation.
Nov. 14: 5,177 dead, mostly in Liberia, Sierra Leone and Guinea, out of at least 14,133 cases in those and five other countries.
Nov. 15: About 160 Chinese health workers arrive in Liberia to staff new Ebola clinic built and run by Chinese personnel.
Martin Salia, a Sierra Leonean surgeon who is a US resident and critically ill with Ebola, is flown from his home country to Nebraska Medical Center.
Nov. 16: Liberia sets national target of no new Ebola cases by Dec. 25.
United States adds Mali to countries whose travelers get Ebola screening.
Nov. 17: Dr. Salia, 44, dies at Nebraska Medical Center, the second person to succumb to Ebola in the United States.
Nov. 18: Cuban doctor Felix Baez treating Ebola patients in Sierra Leone tests positive for the virus.
Nov. 19: 5,420 deaths out of 15,145 cases. WHO says Ebola transmission is "intense and widespread" in Sierra Leone.
Nov. 20: Dr. Baez is flown out of Sierra Leone for treatment in Geneva.
© Thomson Reuters 2014