Yellow fever virus. Coloured transmission electron micrograph (TEM) of yellow fever viruses, cause of yellow fever. Although the viruses coloured yellow appear rounded here, they are of cubic symmetry. They are of the Flavivirus group, containing RNA genetic material. The yellow fever 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 causes yellowing of the skin due to jaundice. Other symptoms include fever, headache and nausea. In serious cases there may be liver and kidney damage, and even death. Yellow fever vaccines provide immunity. Magnification: unknown.