From what I've read...
"low-risk" hpv = visible, external genital warts and can also cause mild abnormal pap tests. This doesn't mean that if you have mild dysplasia that it automatically means you have "low-risk". "High-risk" hpv can also cause mild dysplasia.
"high-risk" hpv = Causes abnormal cell changes in the genital skin, mainly the woman's cervix. Now, I personally have read that some
high-risk hpv's can cause flat warts, but from what I hear, it's not common. I've had HPV for about a year, and just found out a week ago that I have high risk (and assuming I do not have low risk). I've never shown any visible warts that I'm aware of. Everytime I've gone in for my follow-up paps, I get an all clear on the gw front.
I posed this very question a while back over here:http://www.ashastd.org/phpbb/viewtopic.php?t=435
Just scroll down a bit, and you'll find Fredo's response to me in regards to that question.
It's possible that your friend has contracted another strain of the virus from someone other then yourself. A person can have more then one strain...including low and high risks...at the same time. It can lay dormant even for years in a person's system, so it's really hard to say where he may have gotten in from. Unless he was a virgin when you were together...and when I mean virgin, that he never even rubbed genitals, or touched someone down there then touched himself right afterwards. If you haven't yet, I suggest checking out this site's info on the virus right here:http://www.ashastd.org/hpv/hpv_learn.cfm
You may want to direct your friend to it, too, in case he has any concerns/questions.
I'm afraid I'm not really good at this since I'm answering based on what I've heard/read. I'm hoping I didn't make you feel worse! lol! However, I'm sure Fredo can help answer your questions better then I can. He's often been a comfort for me whenever I've posted on this board.