Ebola virus is an RNA virus belonging to the filovirus family, which causes hemorrhagic fever. There are six variants of Ebola virus.
Four of these cause disease in humans: Zaire virus, Sudan virus, Taï Forest virus and Bundibugyo virus.
The current outbreak in the Democratic Republic of the Congo is caused by the Bundibugyo virus. There are no vaccines or specific treatments for this particular variant, which makes the situation particularly challenging.
There are approved vaccines against one variant of the virus, the Zaire virus.
Ebola virus is transmitted between people through body fluids such as saliva and blood. Therefore, healthcare workers who are in close contact with infected people are particularly vulnerable. A particular risk of virus spread is when coming into contact with dead bodies in connection with burial. Sexual transmission also occurs.
Infected people become contagious only after they develop symptoms, and contagiousness increases during the course of the disease. The time from infection to symptom onset is 2 to 21 days.
The illness begins quickly with flu-like symptoms such as high fever, headache, sore throat, gastrointestinal symptoms and muscle pain. Toward the end of the course of the disease, bleeding may occur on the skin and in internal organs.
The mortality rate is estimated to be 50–90 percent in outbreaks in affected African countries. With access to adequate intensive care, the mortality rate is likely to be significantly lower.
The natural host of Ebola virus is believed to be bats. However, the route of transmission is usually indirect, via handling raw meat from other infected animals such as monkeys and deer.
The World Health Organization (WHO) has declared the Ebola outbreak in the Democratic Republic of the Congo and Uganda a "global health emergency."
