Its very common for people to have hepatitis C for many years without knowing. Most of the time Hep C will show no symptoms when it is passed to someone and may do damage to the liver slowly so that people can feel fine for decades.
A blood test is needed to see if someone has hep c. Currently they have treatments available that have a high chance of curing hep c. Its important for the person with hep c to see a doctor and to get a referral to a liver specialist. The doctor will do blood tests and other tests on a routine basis to see how healthy the liver is and will also be able to discuss treatment options.
Hep C is usually passed via blood, it is a strong virus and can live outside the body for several days. The most common way it can pass to someone is if people share drug equipment that could have blood on it, sharp items that may have blood on them like reused tattoo or medical needles etc… You should also be careful not to share any personal care items that may have blood on them like nail clippers, toothbrushes and razors.
Hep C is not passed by activities like hugging, kissing, sharing communal space, sharing a cigarette or drink. Sharing food. To get hep C you need to get the person’s blood into your body.
In regard to precautions in regard to sex it really depends on your situation. They have found that Hep C transmission by sex in monogamous heterosexual couples that are HIV negative is a rare event. They have also found that this small risk does not seem to be related to any specific sexual practice. If someone is unsure and or find that being worried about hep c effects how they feel about having sex with a partner, condoms can be an option in these situations.
I am unsure of your situation, but there is evidence from studies of men who have sex with men that people who have HIV can shed Hep C in their semen and that their receptive partner during anal sex could have Hep C passed to them. If someone was in this situation we would recommend using condoms during anal sex.
Also have a look at the CATIE website as they are a Canadian website and have some great information on Hep C.
Let us know if you have any further questions or concerns.