White Coat Underground

A lurker in the forest

Posted by PalMD on February 12, 2010
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Human papillomavirus (HPV) is a fascinating little bugger. Certain strains can interfere with tumor suppressor genes leading to cancer, especially cervical, anal, and some mouth cancers. Other strains cause genital warts. The vaccine offered in the U.S. (Gardasil) protects against the two strains that cause most cancers and against two strains causing warts. The vaccine has the potential to change the way our population is affected by these diseases.

But we are still learning more about this virus. We know that HPV can be transmitted even without visible lesions. But where are these viruses hiding? A recent study in the Journal of Infectious Diseases may have found one reservoir.

Researchers in Slovenia looked at some of the old data on HPV which suggested that pubic hair follicles might contain HPV. To investigate this further, they rounded up 53 Slovenian males with genital warts, and 53 males without warts to serve as controls. They then sampled the warts and plucked hairs from the scrotum, pubic area, and from around the anus.  They used PCR to find and identify HPV DNA from the samples.  

HPV infections and HPV-related cancers are sexually transmitted, and are strongly affected by the immune system, and HPV-related cancers are particularly common in people with HIV, so the study subjects were screened for the presence of HIV and other immune diseases.  

The researches found significant differences between the two groups studied.  Nearly 70% of subjects with warts had HPV isolated from hair samples, compared to about 13% of controls.  Strains in the hair matched the strains from the warts present.

Now before you sign up for an expensive and uncomfortable series of sessions with the laser, there are some limitations to this study.  The test group were people with warts, meaning they had active HPV disease.  This means that while it is plausible that pubic hair serves as a reservoir for HPV, it is not clear if it actually does serve as a reservoir for transmission of the virus—it could be that hair follicles are only infected when there are other active lesions.  Also, PCR is remarkably sensitive, so it’s possible that the hair samples were contaminated by the warts (although the authors note that “a disposable pair of sterile tweezers and gloves were used for each individual.”  Comforting, that.).

The results from this small study are intriguing, but simply reinforce the need for prevention of transmission via safer sexual practices and immunization.  

References

Poljak, M., Kocjan, B., Potočnik, M., & Seme, K. (2009). Anogenital Hairs Are an Important Reservoir of Alpha‐Papillomaviruses in Patients with Genital Warts The Journal of Infectious Diseases, 199 (9), 1270-1274 DOI: 10.1086/597619

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Comments

  1. #1 JohnV
    February 12, 2010

    13% of people w/o genital warts still harbored HPV in their pubic hair follicles? Asymptomatic carriers and/or who weren’t flaring up at that particular time (or whatever the specific term is for HPV)? Is that normal?

    As to the sensitivity, the paper is behind a pay wall so I can’t look, but a RT-qPCR to give some quantification may have helped to decide between contamination and harboring viral particles.

  2. #2 PalMD
    February 12, 2010

    For detection of alpha‐HPV, polymerase chain reaction (PCR) was performed on all samples with the primers PGMY09/11 and CPI/IIg, which target 450‐bp and 188‐bp fragments of the L1 and E2 genes, respectively [5, 11, 12]. HPV genotypes were determined by restriction fragment–length polymorphism analysis of the PGMY09/11 PCR products or by sequencing the CPI/CPIIg PCR products [5, 9, 13]. For samples in which >1 HPV genotype was detected, genotyping results were confirmed using the Linear Array HPV Genotyping Test (Roche Diagnostics) [5, 9].

  3. #3 Isis the Scientist
    February 12, 2010

    Where are the pictures? I don’t believe anything until I see pictures

  4. #4 M
    February 12, 2010

    While not related to this question, I’ve wondered a few things about HPV and vaccination that I have not found the answer to by simple googling.

    1) Since men obviously can carry and transmit HPV, why isn’t the vaccine available for men?

    2) Why is it not possible to test for HPV in men?

    I’d speculate that 1) is because of 2), since you can’t officially test a vaccine’s efficacy in menu without testing if they have the virus. But I’ve never heard an explanation of this, and if anyone here knows offhand, I’d be interested to hear it.

  5. #5 Uncle Glenny
    February 13, 2010

    So are you going to get a Braziian wax job, documented in minute photographic detail for us?

  6. #6 PalMD
    February 13, 2010

    I like my readers too much to do that to them.

  7. #7 PalMD
    February 13, 2010

    @M
    The vaccine is available off-label for men and boys and will probably be made officially available soon.

    In women, the cancer-causing strains of HPV have a particular effect on cervical tissue which is observable on a Pap smear. In men, the genital tissue is epithelialized and less amenable to the sort of testing we can do on women. And in women, we can only really test the cervix, not the external genitalia. The pap smear looks for changes caused by HPV, and there are newer tests that look for HPV DNA specifically, but these tests are imperfect.

    There is no clear way to screen for penile or oral cancers caused by HPV (and they are not that prevalent), but in some high-risk populations, anal pap smears can be used.

  8. #8 becca
    February 13, 2010

    My son was vaccinated against HPV as soon as it came available, at the same time I vaccinated my daughter. Somewhat to my surprise, our insurance paid for both.