Ebola virus disease, or simply Ebola, is a disease of humans and other primates caused by ebolaviruses. Signs and symptoms typically start between two days and three weeks after contracting the virus as a fever, sore throat, muscle pain, and headaches. Then, vomiting, diarrhea and rash usually follow, along with decreased function of the liver and kidneys. At this time some people begin to bleed both internally and externally. The disease has a high risk of death, killing between 25 percent and 90 percent of those infected with the virus, averaging out at 50 percent. This is often due to low blood pressure from fluid loss, and typically follows six to sixteen days after symptoms appear. The virus spreads by direct contact with blood or other body fluids of an infected human or other animal. Infection with the virus may also occur by direct contact with a recently contaminated item or surface. Spread of the disease through the air between primates, including humans, has not been documented in either laboratory or natural conditions. The virus may be spread by semen or breast milk for several weeks to months after recovery.