I think Hep C might just cause flu-like symptoms when contracted, and then not show symptoms for awhile. There is a specific test for Hep C. A doctor would suggest that test if they knew someone was an IV drug user or had sex with somebody who was an IV drug user.
The person would always carry the disease, and the blood and semen would carry the virus. They would need condoms, and people would need to be careful around any of their fluids--vomit, saliva, semen, blood, etc. Hepatitis lives for a long time outside the body.