Herpes does not live in the bloodstream, it is a virus that resides in the nerve ganglia.
It is mostly spread via sexual intercourse including anal), as well as through oral sex. Someone with a cold sore who performs oral sex on someone can pass HSV onto the other persons genitals. This is the cause of more than 30% of new genital herpes infections.
It is not spread through semen, and can be contagious outside of the area the condom covers and can spread even if no symptons are present. Condoms do reduce the risk by approx 50%, but daily antivirals and abstaining during outbreaks can reduce the risk down to a manageable 1 or 2%.
You can still donate blood if you have herpes. However, if you are having an outbreak they may ask you not to, as your immune system is weaker at the time. But, if anyone refuses to let you donate blood then you need to make sure that you question them on this and tell them to contact the Red Cross
http://www.redcross.org/services/biomed/0,1082,0_557_,00.html or the CDC as HERPES is not contagious via blood tansfusion. (As many as 80% of the population will have either HSV1 or HSV2 or both by the time they are 50). Most will not even be aware they do. If Herpes was contagious via blood, we would all have Herpes!!! LOL
Source(s):
http://www.redcross.org/services/biomed/0,1082,0_557_,00.html
http://www.club462.com
http://www.racoon.com/herpes
http://www.ashastd.org
http://www.herpes-coldsores.com/