Yellow fever virus. Coloured Transmission Electron Micrograph (TEM) of yellow fever viruses (yellow/ red, at centre) on the surface of an infected cell. The cell is white/brown at lower frame. This virus occurs in tropical Africa, Central and South America. It is transmitted to humans when an infected female mosquito Aedes aegypti bites a human. Yellow fever is so-called because it may cause yellowing of the skin due to jaundice. Other symptoms include fever, headache, nausea, and low heart rate. In serious cases damage may occur to the liver and kidneys. About 10% of victims die. Yellow fever vaccines give long-lasting immunity. Magnification: x50,000 at 6x7cm size.