Yes, blood in the semen can transmit the hepatitis C virus. I would suggest some form of barrier contraception (i.e. condoms).
There are various causes of blood in the semen. They include benign and malignant disorders of the prostate gland, seminal vesicles, spermatic cord, and ejaculatory duct system; urogenital infections; metastatic cancers; and vascular disorders. However, it is often impossible to know with certainty whether these conditions are the cause of hematospermia. The cause is idiopathic in a substantial proportion of patients, and the condition frequently resolves spontaneously.
There is no specific treatment for the majority of patients, and the condition usually resolves spontaneously. If it doesn't, I would suggest a urinalysis and possible transrectal ultrasound to evaluate the prostate.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Thanks,
Kevin, M.D.