Factbox: How Ebola started and spreads

(Reuters) - West Africa has grappled with the worst Ebola outbreak on record that has killed at least 8,810 people since March 2014. The following are some facts about the outbreak: Ebola had killed 8,810 people out of 22,092 cases as of Jan. 25, 2015, with the vast majority of deaths and cases in Liberia, Sierra Leone and Guinea, according to the United Nations' World Health Organization. The WHO said on Thursday that the focus of the fight against the virus had moved from slowing transmission of the disease to ending the epidemic. Ebola emerged in a remote forest region of Guinea last March. It has also turned up in Nigeria, Senegal and Mali. Health officials declared Nigeria and Senegal Ebola-free in October. Mali's government declared that country free of the disease on Jan. 18. There is no vaccine or cure for Ebola, a hemorrhagic fever. In past outbreaks, fatality rates have climbed as high as 90 percent. Ebola causes fever, flu-like pains, bleeding, vomiting and diarrhea. Pharmaceutical companies are working on experimental Ebola vaccines and antiviral drugs, but a significant number of doses will not be available until at least the first quarter of 2015. Ebola is not airborne. It is transmitted through blood, vomit, diarrhea and other bodily fluids. Healthcare workers in West Africa have been among the hardest hit by the outbreak. Ebola symptoms generally appear eight to 10 days after infection, but the incubation period can last from two to 21 days. There is a significant window during which an infected person can escape detection, allowing them to travel. However, they are not considered contagious until they start showing symptoms. Recovery from Ebola depends on the patient’s immune response. People who recover from Ebola infection develop antibodies that last for at least 10 years. Ebola patients have been treated in the United States, Spain, Germany, France, Norway, Italy, Switzerland and the United Kingdom. The United States, Britain, France, China, Cuba and international organizations are pouring funds, supplies and personnel into the affected parts of West Africa. Ebola's suspected origin is forest bats. The virus was first identified in 1976 in what is now Democratic Republic of the Congo. SOURCE: World Health Organization and U.S. Centers for Disease Control and Prevention (Compiled by Jonathan Oatis; Editing by Toni Reinhold)