See http://www.pinglaw.com/CM/Custom/STD-Transmission-FAQ.asp for information on a case in Missouri - or http://nbcsports.msnbc.com/id/12468203 for the story of the settlement reached in the Michael Vick herpes case.
I am not a lawyer or associated in any way with a law firm - from what I've read, get a personal injury attorney experienced in this type of case. Most cases are settled before trial. If someone knowingly infects another human being with herpes, they should be stopped. They have no conscience and will do it, or worse, again.