VD SHADOW ON HEALTH Since the war, venereal disease has been steadily increasing, and the number of new cases now stands at more than double the pre-war total. The first thing that everyone should know about venereal diseases is that they can be avoided—by clean living. They are spread by sexual intercourse. Syphilis How are Venereal Diseases caught? and gonorrhœa — the two principal In adults, almost always through sexual venereal diseases—are each caused by a intercourse with a person who has already different germ.