Definition: An infectious, microscopic organism that causes many diseases. Some types of viruses directly target the liver, resulting in hepatitis.
Viruses are not living organisms, but they are able to replicate themselves once they infect an appropriate cell. Once the virus enters a cell, it interferes with the cell's normal functions and starts to replicate itself. After enough copies are made, the virus destroys the cell and seeks out new cells to infect. After enough cells have been taken over by the virus, the body begins to show signs of sickness.
For more information about the five viruses that target the liver and cause viral hepatitis:
