In order for the Euphoria Virus to activate, the virus carrier has to come in contact with an enzyme which can be found in Kagura's bodily fluids, which can probably be assumed to be always through a kiss. (Even though Suitengu saw Kagura as his sister Yui in a trance, Kagura probably didn't do anything more than kiss).
However, Suitengu is shown to have become a Euphoric after he was operated on. So I am wondering, did his Euphoria Virus become active because he had Kagura's father's arm, or was it through some other means that his virus became active?
