The eruptive world population and the mobility of the planet's inhabitants are two major factors responsible for the accelerated evolution of viruses into new frontiers of pathogenicity. Most of the families of viruses mentioned above have produced new strains. Of great concern is the diversificatio of the HIV and the Hepatitis families. This is called a viremia. A wave of viral particle carried through the blood stream to infect organs throughout the body is called a viremic episode.
Many viruses travel free in the plasma.
Others may attach themselves to platelets, lymphocytesi or red blood cells. Recent research has shown that the number of virions involved in infection is much more important than previously realized. In both HIV and hepatitis, several billion new particles may be produced each day. The amount of viral concentration present at any one time is called the viral load. The immune system is placed under constant stress to deactivate these new infective particles, and to regenerate its own decimated cellular components.