Lol, what?? What a fucking pathetic excuse for this manga to give a reason not to infect this person.
Just by checking her out, anyone can tell she is part of a primitive civilization, and even if they somehow knew of diseases and could, however way, eradicate the disease, by understanding their language, can just pretend he's not sick when using her body. I'm fucking pissed how we have an overly pacifist Mc and the manga tries to sugar coat it with dumbass logic.
Anyway, although it bothers me i'll probably still read on as it still seem somewhat unique and interesting despite me losing some of it to this part chapter.