Just remember that it has to get into your blood stream through an opening in your body like a cut or a needle stick, it can't go in through your skin, or your mouth or nose... unless they are bleeding. I know OCD is hard on you, but these are the rules for Hep C, so try to remember that and you'll be fine.
You will come in contact with people who have infectious disease or encounter circumstances all your life and never know it.
According to what you've stated the dried blood would have to contain the virus to begin with and in the case of HCV or HIV the contaminated blood MUST enter the bloodstream to cause infection. This does not occur as easily as you think, otherwise entire families would be infected or for that matter the entire world. I've had hepc for 39 years and no one else in my family except me has it and there were incidences of blood to blood exposure when my children were growing up.
You might want to consider talking to a professional if this is causing you problems. You're only 17 and you don't want to go through the rest of your life with this type of OCD.
Trinity
ocd is right.
Dont worry about it
frijole