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Human papillomavirus

HPV is a common sexually transmitted infection (STI), causing genital warts.

Other strains cause warts elsewhere on the body such as on the hands and feet (veruccas). These are spread through contact. A small number of HPV strains have been associated with an increased risk of cervical cancer, anal cancer and some mouth and throat cancers.

  • About HPV
  • Symptoms
  • Causes
  • Treatment
  • Special considerations
  • Prevention
  • Further information
  • Sources
  • Related topics

About HPV

Over 100 strains of HPV have been identified. Different strains can cause warts in different places. These can occur on your hands or feet, or other areas of the body such as your chest, face or arms.

About a third of HPV strains affect the genital area. Most genital warts are caused by HPV types 6 and 11.

Nearly all cases of cervical cancer are thought to be caused by a small number of HPV strains. Among others, types 16, 18, 31, 33 and 45 have been linked to cervical cancer. These high-risk strains are also associated with anal cancer.

How common is HPV infection?

HPV infection is very common. Most people will have some form of HPV at sometime in their life. Skin warts are most common in children and adolescents. About four to five percent of this age group are affected at any time. Genital warts caused by HPV are the most common sexually transmitted infections seen in sexual health clinics in the UK. In men, genital warts are most common between the ages of 20 and 24. In women, they are most common between the ages of 16 and 19. However, in both sexes they can occur at any age. Although HPV infection is common, most people who are infected don't develop warts or cancers.

Symptoms

HPV infection often has no symptoms. If you have sexually transmitted HPV you can spread it without realising you have it.

If you do develop warts, their appearance varies depending on their location and the strain of HPV you have caught.

Warts usually occur on areas of skin that are likely to be damaged, such as fingers, elbows, knees and the face. Nail-biting in children, shaving of the face or legs and ill-fitting shoes in adults have all been blamed for making warts more likely. Warts can also develop in the mouth, nose or throat. Sometimes warts can spread to surrounding areas of skin.

Warts usually develop three to four months after you catch HPV. However, it can take anything from one month up to two years. Some common types of wart are described below.

Skin warts

  • Common wart (verucca vulgaris). A firm, raised, pink or skin coloured lump with a rough surface that may look like a cauliflower. Often seen alone or in clumps on the hands, fingers, elbows, knees or feet. They are usually smaller than a centimetre in diameter.
  • Plane wart (verruca plana). Small (1-5mm) smooth, flat topped or slightly raised. They affect face, hands, or legs and are usually skin coloured, light brown or greyish, but are sometimes pigmented. Can occur alone or in groups.
  • Filiform wart. Long, slender growths on lips, eyelids, face or neck.
  • Plantar wart. Commonly known as veruccas, these occur on the soles of feet. They can be painful when under pressure. Small black dots can be seen on the surface under the hardened skin (callus).
  • Mosaic warts. These occur when several plantar warts group together into a cluster.

Genital warts

In women, genital warts generally appear on the inside or outside of the vagina, on the cervix (neck of the womb) or around the anus. In men, the warts are generally found on the tip or shaft of the penis or around the anus. The warts are generally painless but can sometimes itch, feel sore and occasionally bleed. Genital warts can often grow larger if you are pregnant.

Causes

HPV infection can spread in several ways. It is most easily transmitted by direct skin contact with a wart. Some skin warts may also be spread by touching moist surfaces, such as towels, shoes or floors in swimming pools and changing rooms that have been in recent contact with a wart.

Genital warts are spread through contact during sex. Even if you don't have a wart you can still transmit HPV because the virus can still be shed.

HPV can sometimes pass from a mother to child during vaginal birth.

Treatment

HPV infection is only treatable when it's causing warts. This treatment is mainly cosmetic - it doesn't affect the HPV infection itself. There is no direct treatment for the virus. In some people their immune system can get rid of the HPV infection quickly and they develop immunity to that strain. In other people the virus may remain for some time. HPV usually clears within 2 years, but if you have a weakened immune system this may take longer (See Special considerations).

Skin warts

Most skin warts don't need to be treated. In children, between 30 percent and 50 percent of veruccas disappear within 6 months, although they may last longer in adults. One study found that two-thirds of skin warts disappear on their own within two years.

However, you may want to treat a skin wart if it is unsightly, if it's painful or itchy, or to stop it spreading to surrounding areas.

You can buy creams, gels, plasters and home freezing kits over the counter for treating skin warts. Always read the patient information leaflet that comes with a medicine, and if you have any questions ask your pharmacist for advice. If the treatment isn't effective, talk to your GP. Over-the-counter treatments aren't suitable for treating genital warts (see below) or warts on the face.

Genital warts

Most genital warts will disappear on their own after about 18 months, and you may decide you don't want treatment. However, they can cause you distress, and can also spread, making them harder to treat. On rare occasions warts can develop into small cauliflower-like growths.

Genital warts are treated according to their size and location. Don't try to treat these at home, visit your GP or a genitourinary medicine (GUM) clinic. These are also known as sexual health clinics.

  • Chemicals may be used to remove visible warts.
  • Cryotherapy is a technique which freezes the wart using liquid nitrogen.

There are other less common types of treatment.

  • Laser therapy can be used on some warts. For this you will need a local or sometimes general anaesthetic.
  • Heat treatment (electrocautery) can get rid of the wart. Again, you will need a local or sometimes general anaesthetic.
  • Surgery can be used to remove the wart, for which you will also need a local or sometimes general anaesthetic.

You may need repeat treatments to get rid of the warts and they can come back.

If you have genital warts you may have been exposed to other sexually transmitted infections. At a GUM clinic you can be tested for other diseases as well. If you have genital warts or HP current or recent sexual partners need to be informed. The GUM clinic will be able to do this for you if you give them the information they need, allowing you to remain anonymous.

Special considerations

Cancer risk

Some HPV strains, such as 16, 18, 31, 33 and 45 and others, have been linked with cervical, anal and penile cancer. Most of these strains are different to the ones that cause genital warts, so having genital warts doesn't always mean you have a higher risk of cancer. But both the genital wart types and the cancer-associated types of HPV are sexually transmitted, so if you have genital warts you may also be infected with other types of HPV.

If you are invited to have cervical screening (a smear test) it's important that you attend. This can pick up signs of cervical cancer before it has developed. Cervical screening will still be important even for women who have had the new HPV vaccine (see below).

Weakened immune system

If you have a weakened immune system, caused, for example, by AIDS or drugs that suppress your immune system after an organ transplant, you may not respond as well to treatment and the risk of the warts coming back is higher. Your risk of developing cancer caused by HPV may also be increased. Follow-up appointments will ensure that your treatment is tailored to your needs.

Prevention

Contraception

Using a condom is thought to reduce the chances of catching HPV, but it may not always provide complete protection because the condom may not cover the area of the body where the wart or wart virus is. Having fewer sexual partners will also cut your risk of getting HPV.

Vaccination

A vaccine against four strains of HPV linked with cervical cancer and genital warts has been developed. It protects against types 6 and 11, which cause warts, and types 16 and 18, which account for about 70% of cervical cancers.

From 2008, the vaccine will be offered to all girls aged 12 to 13 in the UK. It's hoped that this will eventually lead to a reduction in the incidence of HPV and genital warts in the future, and cut the incidence of cervical cancer.

The HPV vaccine doesn't protect against all cancer-causing types of HPV, or against the development of cancer in women who have already been infected with HPV. Therefore cervical screening will still be needed even after vaccination is introduced.

Further information

Terrence Higgins Trust

Condom Essential Wear

Sources

  • Warts (including veruccas). Clinical Knowledge Summaries. http://cks.library.nhs.uk, accessed 14 November 2007
  • General information - genital warts. Health Protection Agency. www.hpa.org.uk, accessed 13 November 2007
  • Cumbria and Lancashire health protection newsletter. www.hpa.org.uk, accessed 13 November 2007
  • Human papillomavirus. NHS Cancer Screening Programmes. www.cancerscreening.nhs.uk, accessed 14 November 2007
  • Kumar P, Clark M,. Clinical medicine. 6th ed. London: Elsevier Saunders, 2005. 1057
  • United Kingdom National Guideline on the Management of Ano-genital Warts, 2007. British Association for Sexual Health and HIV. www.bashh.org
  • Pattman R, Snow M, Handy P, Sankar K N, Elawad B. Oxford handbook of genitourinary medicine, HIV and AIDS. Oxford University Press, 2005: 250-261
  • Immunisation. Immunisation for life. www.immunisation.nhs.uk, accessed 15 November 2007
  • Vaccination against cervical cancer. Royal College of Obstetricians and Gynaecologists. www.rcog.org.uk, accessed 30 November 2007

Related topics

  • Genital warts
  • Warts and verrucas