[Question #7233] Non-sexual Transmission of HPV

6 months ago
A few pages  on sites like the Mayo Clinic and Elsevier warn fomites may cause HPV infection. But experts here categorically dismiss flakes of skin, blood, semen and any other bodily secretion, and towels, dirty underwear, toilet seats, high-touch surfaces and fomites of any description. You also need not worry about children who play hide and seek in hampers of dirty laundry or cuddle on your lap while you're in a bikini: they don't contract the HPV of the adults that surround them. What household transmission there is, is passed skin-to-skin and mostly spread from the more benign hand warts of caregivers.

In short: you hold that in all the years of research not one single study has demonstrated the possibility of non-direct, fomite transmission, even under lab conditions. Rather, fomites are the go-to for unexplained infections. Indirect transmission is not proven, it's assumed. You say: pics or it didn't happen. The worrying articles say: well, how else do you explain it?

Is that a fair summary of your take? HPV by fomite is urban legend?

Does transmission then occur only through living, symptomatic skin? As in, are warts the sine qua non for transmission? No warts, no danger of HPV?

Does it make sense to get vaccinated in your later years? From what I've read, it won't take if you're infected and (for a man) there's no way of knowing for sure if you are.

Short answers are fine, wherever you are sure. I'll ask for clarifications in the follow-up.
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
6 months ago
Welcome to the forum. Thanks for your confidence in our services and a sophisticated and important question. I'm taking the opportunity for a longer, blog-like reply that may be useful in reply to additional questions in the future.

The main thing to understand is that there is essentially no research that has been conducted to explain HPV infections other than genital to genital -- such as looking at partner infection rates as a correlate of number of episodes of sex with an infected person, condom use, etc. Otherwise, the evidence is all indirect -- such things as the sites at which DNA of genital HPV types can be detected (mostly genital and anal, less freqent oral, but also other sites, such as under fingernails and on toilet seats); and the near absence of people with genital warts or other genital HPV infections, such as abnormal pap smears, who have not been sexually active; or the near absence of non-sex-partner household contacts who acquire HPV while sharing toilets, showers, towels, eating utensils, and often beds with persons with anal or genital HPV. All these give strong clues, but that's all. Most people with genital HPV who initially claim to have not been at risk sexually turn out to have risks they initially denied or didn't recognize. (Think of sexually abused kids who may never acknowledge it, or who don't even really understand what happened to them at a young age.)

Why do so many resources claim non-sexual transmission via towels or other fomites? Many contributing factors (these are common sense guesses only):  easier for a doc to explain in a minute or two, without getting into prolonged and frought discussions about past sexual events, partners who may be unfaithful, and so on. Assumption that detection of HPV DNA on an object (or in someone's genital area) means the infection is potentially transmissible, which isn't necessarily true. And trust me on this:  even such claims of non sexual acquisition of HPV are rare. However, with a country of 360 million, of which at least 80% have or have had HIV by the time they reach mid-adulthood, and many of which persist, even if only one in a thousand claims nonsexual acquisition, that's still millions of people -- i.e. a statistically rare event that still means large numbers. And the evidence is strong that most of those claiming to have not been at risk sexually in fact have been at risk. For hundreds of eyars, all STDs have often been attributed to nonsexual infection, because of stigma, unwillingness to confront a spouse who is fooling around (consider the male-female power imbalance through all history), and so on. Hence telling those wronged spouses that their dear husband must have caught his gonorrhea or syphilis in a public toilet. It was BS then and it's BS now.

Are there a few infections not sexually acquired? Surely yes. If nothing else, a quarter to a half of all babies are born to moms with detectable anogenital HPV, so some folks probably acquire it during birth, with infection not documented until much later. And maybe there are a few cases from fomites etc. It's impossible to prove this doesn't happen, but all the epidemiologic evidence is that it's rare if it occurs at all. Does that put fomites into the "urban legend" category? Maybe not quite, but it's close.

To your specific quesitons:

1) Warts are definitely not the sine qua non for transmission. The large majority of genital HPV infections cause no warts and yet they are efficiently transmitted. You cannot expect to avoid HPV just by avoiding partners with warts. That would make absolutely no difference in risk.

2) It isn't true the vaccine "won't take" in older persons. The amount of antibody in response to vaccination declines with rising age, but the vaccine is still 100% protective against the 9 HPV types covered by the vaccine. The reason that the vaccines were not initially recommended after age 26, and now advised only up to age 45, is not reduced effectiveness, but a rising likelihood with age that someone has already been infected with most or all the vaccine strains; plus the statistical infrequency of new HPV infections as age increases, with reduced partner numbers. However, some persons well over age 45 remain susceptible and are at risk, and should be vaccinated regardless of age. As one common example, consider the long marriage, with no sexual infidelity, that comes to an end through divorce, partner death etc. Such a person likely has not been infected with several of the 9 vaccine types and might benefit, especially if s/he is likely to get into a heavy duty dating game, i.e. lots of younger partners.

I hope these comments are helpful. As you suggest yourself, I'm happy to answer any clarifying quesitons.

HHH, MD
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6 months ago
If fomite transmission has just enough credibility to not completely rule it out, is there any way to sensibly integrate HPV awareness into basic hygiene? Is skin flaking something to be wary of, when you spot some wayward particles in your underwear, or is the risk of HPV simply so pervasive that anything other than relying on female partners, and women in general, to take their pap smears seriously is fruitless anguish?

As to getting vaccinated in my late forties, with a sexual history, my befuddlement is whether a vaccine will do any good against any variation I may be infected with. Which being older, HPV has had a few chances to do. Or can it help clear up existing infections? Then again, I suppose that if it covers nine types, there's a very good chance it may head something else of at the pass.

(PS: halfway in the third paragraph you wrote "However, with a country of 360 million, of which at least 80% have or have had HIV by the time they read mid-adulthood..." Obviously you meant HPV. If you choose to edit, feel free to remove this PS)
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
6 months ago
I did not say that fomite transmission has any credibility at all. Good hygiene is fine, of course, but makes no difference in HIV risks or transmission. And yes, the main prevention strategies are vaccination and, for women, pap smears. Most of the population is not terribly concerned about HPV -- relatively few go through "fruitless anguish" about it.

Recent research shows the HPV vaccine probably helps prevent reactivation of existing HPV infections with the 9 vaccine types. (Initially it was believed the vaccine has no effect at all on existing HPV infections.) However, that effect is very mild and is not a reason to get vaccinated. The only reason for vaccination is to prevent new infections. If you have had an average sex life, i.e. with several partners over the years, you have been infected with at least some of the vaccine types, maybe severl of them. At your age, I would not recommend vaccination. Also, because you are beyond the recommended ages, your medical insurance probably wouldn't cover it, so you'd be out several hundred dollars with little or no benefit.

Sorry for the typo:  reach, not read. I'll correct it. Otherwise the statement is correct.
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5 months ago
I acknowledge that I take my sense of obligation for the sexual health of my partners, and worry over fomite transmission to others, more serious than is common and pompously so, perhaps. But I don't know how to find fault with myself for it. If you know where to draw a line, in ones obligations toward others in this regard is general and HPV specifically, I would really like to hear it.
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
5 months ago
A hundred pages could be written about one's obligations for one's sex partners' health, whether it's HPV, any other STD, or the non-infectious aspects of sexual health. Certainly I cannot and do not fault you for being careful and for your concern for your partners' welfare. The world would be a better place if more people had the same inclincations. But remember that everybody has or gets genital HPV. Learning that a particular partners has it, has had it, or fears s/he might have it makes no difference in that person's risk of becoming infected or having an important health outcome as a result of HPV. That's not to say you should ignore it. But it does suggest that the level of caution you are speaking about really isn't necessary.

That completes the two follow-up exchanges included with each forum question and so ends this thread. I hope the discussion has been helpful. Best wishes and stay safe.
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