 Examples include the measles, in which primary viremia occurs in the epithelial lining of the respiratory tract before replicating and budding out of the cell basal layer (viral shedding), resulting in viruses budding into capillaries and blood vessels.Passive viremia is the introduction of viruses in the bloodstream without the need of active viral replication.Examples include direct inoculation from mosquitoes, through physical breaches or via blood transfusions.