Viral infections commonly result in skin lesions and rashes. Typically, a rash occurs, and resolution is seen after the immune system clears the infection. This is a common pattern in children. Some viruses lie dormant in the host’s cells and reactivate at a later time, sometimes years later. Another pattern is a chronic infection. Viruses can infect the skin by direct inoculation, by local spread, or by systemic infection. Viruses are microscopic organisms whose survival is entirely dependent on using the DNA of other living cells (called host cells) to develop and multiply.

The virus growth cycle has four stages. First, the virus attaches to a receptor on the cell’s membrane. Second, the virus penetrates the cell either by fusing with the membrane or by being engulfed by the cell and delivered into its interior. Third, the virus is transported into the cell’s nucleus where the virus uses the host cell’s DNA to reproduce. Finally, the infectious virus particles (virions) are assembled and released from the host cell. The length of this cycle varies and can last several hours to many years (latent infection).