You probably didn't realize that there are at least three separate issues embedded in your question. First, it is true that HPV can be detected on inanimate objects (toilet seats, and perhaps textiles like underwear, bathing suits, or towels); and under the fingernails of infected persons. There's no controversy about this:  many scientific reports have documented HPV on such objects. However (second), the only way to detect HPV is looking for DNA, and DNA alone doesn't necessarily mean living, transmissible virus. Third and most important, it is clear that contamination of such objects presents little or no risk of transmission. Nobody gets HPV from toilet seats, towels, or shared intimate clothing. For example, roommates never catch their roomies' HPV infections, and children never catch their parents' genital HPV, despite continous sharing of bathrooms, kitchens, etc (and in some cases, shared towels or underwear). For that reason, the other two issues -- existance on such objects and whether DNA denotes live virus -- really don't matter.

I cannot say where Dr. Lin gets his information, but his statement about HPV transmission from underwear is not supported by any scientific evidence.

Bottom line:  No worries. That said, I would of course recommend that people not share underwear or other intimate clothing without laundering between uses. But this is mostly simple esthetics more than a health issue. To the extent there might be helath risk, it's more for skin infections like staph, strep, and that sort of thing -- not HPV or any other STD.

I hope these comments are helpful. Let me know if anything isn't clear. 

HHH, MD

If you'd like to cite some of the "many studies" of nonsexual transmission, I would be happy to comment on them.

I assume you worked at an std clinic of some sort, it seems logical you would not have come across a non-sexual transmission case, since person's in question probably would not go to an std clinic if they have not been sexually active? I would guess 90 percent of the population is sexually active so it will always be easy to deduct that it came from that activity. I am just perplexed as to why there are so many studies that focus on non-sexual transmission, and makes me worried for my siblings. 

That's an insightful comment:  of course you are right that persons in STD clinics are not representative of the general population. However, there have been many, many studies of HPV epidemiology outside STD clinics, e.g. reproductive health and student health clinics, surveys of people in the general population (look up NHANES and Ad Health as two population-based health surveys that have analyzed HPV). They too show that the vast majority of genital and anorectal (and almost all oral) HPV infections are attributable to sexual transmission. I disagree "there are so many studies that focus on non-sexual transmission". I am not aware of them, which I why I offered you the opportunity to cite some of them.

One potential nonsexual route that is well understood is perinatal transmission during vaginal delivery, resulting in HPV in newborns. It is speculated but not certain that some such infections may persist and be first diagnosed many years later. And of course there are all the HPV strains that cause common hand and foot warts, especially in childhood -- always known to be nonsexually transmitted. But when it comes to the HPV types that dominantly cause genital and anorectal infections, and also oral infections with the genital types, there are few exceptions to sexual transmission. If nonsexual transmission occurs regularly, it is uncommon -- and even that doesn't necessarily imply that shared intimate clothing is a mechanism of transmission. If that happens, it also is rare.

Bottom line:  there is no doubt that the vast majority of genital and anorectal infections are sexually acquired. And there is NO evidence of household transmisison, or any reason for you to be worried about your siblings' risk of HPV. Assuming they are or will someday become sexually active, that's when they (and you) need to be concerned about their HPV risks. And of course they should be immunized to prevent infecion the the 9 HPV types that cause over 90% of important HPV related health problems. Looking to nonsexual acquisition while ignoring the known important routes is nonsense.