All it takes to transfer HPV is epithelial cells rubbing against epithelial cells that contain the virus. This virus does not require a fluid transfer like AIDS of saliva or semen. You think of all the ways in which that can happen. Now given that it isn't transferred through a handshake, you have to consider the kinds of cells that it is attracted to. Here we are still discovering things, but clearly the moist squamous layer of the epithelium on all openings to the body, are prime places for it to reside. Perhaps some of you have read recently that Farah Fawcett has just been diagnosed with anal cancer. This is also a place that is lined with squamous cells, and she likely came to this cancer through HPV, since anal cancers are like oral cancers, predominantly SCC. Remember that it can be dormant in your body for years. That means unless you guys were virgins when you married, (not too many people these days) it could be from some relationship prior to you. It is not a new virus or a new problem. It is on people's radar now because of the vaccine, but it has been known of for half a century or more. But keep this in perspective, read what I said about how many people in the US are going to get HPV. It is very ubiquitous, it is everywhere, and an Australian team has found it associated with breast cancer. And out of over 100 versions there are only a handful that cause malignancies, and if you get one of those there is no guarantee that you will get a cancer, your immune system may eliminate it prior to that kind of event.