The presence of virus parasites in the blood. Viraemia can arise at certain stages in viral infections. Certain viruses, such as those responsible for yellow fever, viral hepatitis, and poliomyelitis, are transported in the bloodstream to their target organ or tissue, for example the liver, where they multiply. Others, such as the rubella virus and HIV, multiply in, and spread via, particular white blood cells. If viraemia is a feature of viral infection, there could be a risk that the infection will be transmitted to other people, in blood or blood products, or via insects that feed of the blood.