We've traced coverage of the outbreak, and tracked its progress in the timeline below, as reported by the C.D.C. and the W.H.O.:
January 2014: Believed to be the month of origin of this outbreak, when the virus infected its first host and incubated.
February 2014: First cases of Ebola are reported in Guinea.
March 25, 2014: After suspected cases arise throughout its rural districts of Guekedou, Macenta, Nzerekore, and Kissidougou, the government of Guinea officially reports an outbreak of Ebola. Suspected cases are also reported in Liberia and Sierra Leone. Guinea enlists Doctors without Borders to establish Ebola treatment centers throughout the affected regions.
March 27, 2014: The virus reaches Guinea's capital of Conakry, the most populated—the city is home to 2 million people—site the outbreak has affected so far. The Bernhard-Nocht Institute of Tropical Medicine in Hamburg, Germany, and the Institut Pasteur in Dakar, Senegal, join the efforts of Institut Pasteur in Lyon, France, testing samples. Researchers confirm the virus is a strain of Ebola that had originally been discovered in Zaire (now Democratic Republic of Congo) in 1976.
March 29, 2014: The virus is confirmed to have reached Liberia.
March 31, 2014: More international organizations arrive in the region: The International Red Cross, Pentecostal Mission Unlimited, and Samaritan's Purse set up to spread awareness campaigns and distribute protective equipment. The W.H.O. leads the international response, and the C.D.C. sends a five-person team to help.
April 1, 2014: Guinea reports its first case of Ebola in the Djingaraye district, much farther north compared to the previously reported districts, indicating a new outbreak origin point.
April 7, 2014: The number of fatalities crosses 100 people, with 95 deaths in Guinea, and 7 in Liberia. Some of the cases include infected health workers.
April 30, 2014: The number of fatalities crosses 150 people, with 146 deaths in Guinea (16 of those being health care workers), and 9 deaths in Liberia.
May 27, 2014: The number of fatalities reaches 200 people, with 186 deaths in Guinea, 9 in Liberia, and 5 in Sierra Leone—the first deaths reported in the country. The WHO and CDC confirm that the country's Kailahun district is the outbreak's hot spot, while laboratory testing begins in the city of Kenema.
May 28, 2014: For the first time, cases are reported from the counties of Boffa, Boke, and Dubreka in western Guinea, covering a new region of the country.
June 2, 2014: The first suspect case is reported in Liberia since April 9, and investigations begin to contain yet another outbreak point. The stretch of time between the reports in Liberia exceeded the 21 days for Ebola to incubate.
June 18, 2014: The number of fatalities crosses 300 people, with 264 deaths in Guinea, 24 in Liberia, and 49 in Sierra Leone.