Ebola virus particles, coloured transmission electron micrograph (TEM). Each particle consists of a ribonucleic acid (RNA) genome within a nucleocapsid (purple), which is surrounded by a glycoprotein envelope (orange). The virus causes a severe, and often fatal disease in humans and nonhuman primates (monkeys, gorillas and chimpanzees). Symptoms include fever, fatigue, headache, muscle aches, vomiting, diarrhoea and haemorrhaging (internal bleeding). There is no cure for the disease, but three quarters of patients can recover if provided with sufficient medical support.