Factbox: The worst Ebola outbreak on record

West Africa is struggling with the worst Ebola outbreak on record, and a Liberian man who was the first person diagnosed with the virus in the United States has died. Below are some facts regarding the outbreak: - The outbreak has killed 3,879 people, out of 8,033 cases as of Oct. 5, predominantly in Liberia, Sierra Leone and Guinea. Ebola, which emerged in a remote forest region of Guinea in March, has also turned up in Nigeria and Senegal, but officials say the disease has been contained in those two countries. - There is no vaccine or cure for Ebola, a hemorrhagic fever. In past outbreaks, fatality rates have reached up to 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 between two and 21 days after infection, meaning 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. - The U.S. Centers for Disease Control and Prevention (CDC) has estimated that the number of infections could rise to up to 1.4 million people by early next year without a massive global intervention to contain the virus. - 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 known as Democratic Republic of the Congo. SOURCE: World Health Organization and U.S. Centers for Disease Control and Prevention (Compiled by Lisa Shumaker and Tom Brown)