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HPV and Genital Warts

Human papilloma virus (HPV) is the most common sexually transmitted infection seen at sexual health clinics in the UK and it is likely that most of us have had HPV at some time in our lives — although we may not have known it. So what is HPV, how can it be prevented and treated, and what does papilloma mean anyway?

Papilloma means a growth or wart, which is why HPV is also known as the 'wart virus'. In practical terms, however, only about 10% of people with HPV develop warts. The vast majority of people with HPV don't, and are therefore unlikely to know that they are infected or that they may be passing the virus to their sexual partner(s).

Young sexually active people are at greatest risk of getting genital HPV, with the highest rate of infection in those between the ages of 20 and 24. Recent research suggests that many young women may become infected with the virus during their first sexual experience, and the risk of infection increases with the number of sexual partners. HPV prevalence seems to decrease with age.

What is HPV?

There are thought to be more than 100 types of human papilloma virus that can infect the body. Some strains lead to common warts on people's hands and feet, but these are different from genital warts and cross-infection is extremely rare. About 30 types of HPV affect the genital area. Some types cause genital warts, others cause changes in cervical cells that may lead to cervical cancer, but most HPV infections cause no symptoms at all and go away on their own.

How is the virus spread?

Genital HPV is highly infectious, particularly when warts are present, and is spread mainly through direct skin-to-skin contact with the infected area. Genital HPV is passed on during sexual contact, including vaginal and anal sex, oral sex and, while less risky, non-penetrative sex play. It is also possible for sex toys to carry an infection from one person to another. In rare cases, HPV may be spread without direct sexual contact. It may be possible, for example, to pick up the virus if you use a towel to wipe your genitals after it has been used by someone who has HPV or genital warts.

Can HPV be spread from woman to woman?

Lesbian sex is generally considered low risk for sexually transmitted infections (STIs), but research shows that HPV can be spread between women. Recent studies suggest that HPV is more common among lesbians than previously thought, and is as likely to affect lesbians who have never had sex with a man as those who have.

How do I know if I have HPV?

Genital warts are the only visible sign of HPV infection, but they may not appear for weeks, months or even years after infection occurs, if they appear at all. Women are more likely than men to develop warts, and they can grow on the lips of the vulva, around the clitoris, inside the vagina, around the urethra, on the cervix, on the area between the vagina and the anus (perianal region), and in and around the anus itself. In men, warts tend to develop on the tip and shaft of the penis, on the scrotum, as well as in and around the anus. Although rare, genital warts may develop in a person's mouth or throat if infected through oral sex.

Warts may appear as small red or white bumps, they may grow alone or in cauliflower-like clusters, or they may be flat and barely visible.

Genital warts are generally not painful, but may be itchy or uncomfortable. You may not realise you have warts, particularly if they are small, inside the vagina or on your cervix.

How is HPV diagnosed?

HPV is usually diagnosed based on the presence of genital warts. If there are no obvious warts, but infection is suspected (because a partner has warts, for example), the doctor or nurse may apply a solution that turns warts white, making very small or flat warts more visible.

An abnormal smear result may be a sign that you have been exposed to HPV, but not all cervical smears can detect current HPV infection. If your smear result suggests HPV might be present, you may be scheduled for another smear, or for a colposcopy. During a colposcopy, a specially-trained doctor or nurse looks at your cervix through a microscope (the colposcope) for signs of HPV and s/he may take a sample (biopsy) of cervical tissue for further investigations.

A new type of smear test, which uses liquid-based cytology (LBC) to sample and store cells from the cervix, offers a more accurate and quicker way of diagnosing HPV, but is not widely available in the UK. LBC is currently being piloted (tested) in clinics and GP practices in Bristol, Newcastle, Norfolk and Cardiff. Depending on the results, LBC may be available for national use over the next couple of years. (For more information about the trials, contact the NHS Cancer Screening Programmes press office on 020 7838 4890)

If you don't have visible genital warts and your smear result doesn't show signs of HPV, there is currently no other way of knowing whether or not you have the virus.

HPV — how will it affect my health

Fortunately, most HPV infections go away on their own within six months to two years without causing any complications or harmful long-term effects. For people with genital warts, the psychological and emotional impact of having warts is often the worst part of HPV. Some infections, however, may be linked to other problems, including recurring warts, other sexually transmitted infections (STIs) and cervical cancer.

Recurring warts

In some people, warts may recur months or years after their initial infection, even if they have been treated and have not been exposed to HPV again. This is because the virus may stay in the skin without showing any signs and then appear suddenly. It is thought a recurrence of warts may be related to stress or a weakened immune system that enables the virus to become active again.

Other STIs

If you have HPV you may have other sexually transmitted infections as well. Research shows that 20 to 30% of people diagnosed with HPV are found to have another STI at the same time. Screening for other sexually transmitted infections should be offered when you are diagnosed with HPV. A survey of GPs, however, revealed that most don't offer additional screening or refer patients on to a sexual health clinic for screening. If you want to be tested for HPV and/or other STIs, go to a sexual health clinic (also called a GUM clinic). They are free, confidential and better equipped than most GP surgeries to test for, and treat, a range of STIs. See Resources for details on how to find a GUM clinic near you.

Abnormal smear results and cervical cancer

Some types of HPV can lead to abnormal cell changes on a woman's cervix. These changes are known as CIN (cervical intra-epithelial neoplasia), which means 'new changes in the outer layer of the cervix'. In many cases, abnormal cells revert back to normal without treatment, but sometimes they do not. If left untreated, these cells may develop into cervical cancer, but it usually takes 10 to 20 years for this to happen. Fortunately, the progression to cervical cancer can be easily prevented if abnormal changes are found and treated early. Smear tests are currently the only way to detect abnormal cell changes, and are therefore the best way to protect yourself from cervical cancer.

If you have been diagnosed with HPV, you may be scheduled for more frequent cervical screening — every 6 to12 months — to keep an eye on cervical cell changes. If the cells do not return to normal, or changes are severe, you and your doctor will need to consider treatment options to remove the abnormal cells. (For more information, see the Women's Health online Cervical Screening and Abnormal Smear booklet.)

If you have visible genital warts, you probably do not have a type of HPV that is linked to cancer.

The two most common strains of HPV linked to cervical cancer are HPV 16 and 18, but most women with HPV, including those infected with type 16 or 18, do not develop cancer. Other strains of the HPV virus have also been linked to cervical and other more rare cancers, such as vulval and anal cancer.

Podophyllin is a chemical treatment derived from a plant extract. It is applied as a mild solution directly to genital warts. Podophyllin is poisonous to human cells and stops warts from growing by interrupting the natural growth process of the body's skin cells. It must only be applied by a trained healthcare professional, and a petroleum jelly should be applied to the skin around the warts to protect it from irritation or burns. The treatment must be washed off four hours after application or it will burn your skin.

Podophyllin treatment may need to be applied, at a clinic, several times over a 2 to 3 week period and is only appropriate for external warts. If after a few weeks the treatment is unsuccessful, an alternative treatment should be considered to avoid side effects. Podophyllin, while applied locally, can affect your whole body if you are exposed to too much of it, and side effects may include severe skin irritation, dizziness, confusion and damage to the nervous system. Some experts have recommended Podophyllin no longer be used to treat genital warts.

It is not safe for use during pregnancy.

Studies show that the recurrence rate of warts following podophyllin treatment may be as high as 40% to 60%.

Podophyllotoxin

Podophyllotoxin, the active ingredient in podophyllin (above), is available in a preparation that is safe for self-application and does not need to be washed off.

Podophyllotoxin is only for use on small external warts and is available on prescription. It is applied, at home, usually twice a day for three days. If the warts have not disappeared after four 'rest days' following treatment, the three-day-on/four-day-off treatment may be repeated for up to four weeks. You should be given detailed instructions with your prescription.

Podophyllotoxin may cause soreness and mild skin irritation. If you have questions about how to use the treatment, talk to the chemist, your GP or nurse practitioner, or contact your local GUM clinic.

Podophyllotoxin should not be used during pregnancy.

Information on recurrence rates varies greatly. It may be anywhere between 10% and 90%.

Trichloroacetic acid (TCA)

Trichloroacetic acid works more quickly than podophyllin and has no systemic (far-reaching) side effects. It works by chemically burning away the warts and must be carefully applied by a trained healthcare professional. As with podophyllin, using vaseline may help protect the surrounding skin. You may feel a painful burning sensation for 5 to 10 minutes while the acid destroys the warts.

There is conflicting information about whether TCA is safe for use during pregnancy.

Warts have been found to recur in about 35% of cases treated with TCA.

Interferons

Interferons are antiviral drugs that may be applied as a cream or may be injected directly into warts. Interferon treatments are rarely used because there are issues around safety, efficacy and expense.

Imiquimod

This is a relatively new treatment that stimulates (boosts) the body's immune system to fight the wart virus. It comes as a cream to be applied to the affected skin and should not be used internally on vaginal, anal or cervical warts. Imiquimod does not boost your entire immune system; it only affects the area of skin it is applied to.

Imiquimod may take up to four months to work and can be self-applied at home. The cream is used three times weekly but must be washed off after 6 to 10 hours. It may cause skin irritation in some people, so if you have a severe skin reaction to the cream, stop using it and see your GP or go to a GUM clinic.

Imiquimod should not be used during pregnancy.

Recurrence rates appear to be relatively low, between 13 and 20%, but additional studies are needed to confirm this data.

Written by Tamara Beus and published in printed form by Women's Health (2002)

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