Louce or lice are species specific so altho guinea pig lice can crawl on you or others they cannot live and breed off of you. So once all guinea pigs in the home are treated with Revolution (was it topical, oral or injection?) several times there should be no more food for them. Just make sure you do at least 2-3 treatments to be sure they are gone. Lice are difficult to get rid of because they can live off host for some time and since they are not blood sucking (they digest the oils that pour out of the skin when they scrape it with their teeth) oral and injections tend to not work well, if at all. In my experience with lice the topical (skin drops) were the best for these critters. Oral and injections are good for blood sucking mites, ticks and fleas.