The phrase "viral load" refers to the amount of a virus in the bloodstream. In this case, the virus is hepatitis C.
What does alcohol do to your viral load?
The more drinks a person has per week, the more virus he or she will tend to have. Why?
Heavy alcohol use weakens the immune system, so the more you drink, the fewer resources you have to fight the hepatitis C virus.
Alcohol is processed and broken down in the liver, so the harder the liver has to work to process alcohol, the more freedom the virus has to do damage.
