Volunteers lower a corpse of an Ebola victim into a grave in Kailahun, Sierra Leone, July 18, 2014. Health officials announced Friday that the Ebola virus death toll has climbed to 2,097 out of 3,944 known cases. Reuters

The death toll of the current Ebola outbreak in West Africa has reached 2,097 out of 3,944 known cases, the World Health Organization announced Friday. This epidemic is the deadliest and most widespread in Ebola's known history, and officials fear as many as 20,000 people could become infected before it is over.

The death toll chiefly includes cases in Liberia, Sierra Leone and Guinea. The epidemic has been escalating now for six months and is slowly spreading to other countries. Just this week, Senegal – a major hub for tourists and travelers – reported its first Ebola patient. Doctors in Israel were testing a Nigerian visitor for possible Ebola infection Friday after she was admitted to a hospital with a fever. She is in isolation until health workers can determine if it is the virus, a spokeswoman for the hospital said. Health officials in the U.S., Spain, Thailand and Britain have also been following potential cases.

Tom Frieden, director of the U.S. Centers for Disease Control and Prevention, said this week the outbreak was “spiraling out of control.” A separate strain of the virus was discovered in the Democratic Republic of Congo, where Ebola was first identified in 1976, according to WHO, and has already killed at least 31 people. However, experts say the outbreak is unrelated to the Ebola outbreak in Liberia and neighboring countries. The fatality rate of the disease is about 50 percent.

Here is where the outbreak has taken hold: