Ano-Genital Warts (HPV)

What are ano-genital warts?
Ano-genital warts usually first appear as small, painless bumps in, on or around the cervix, vagina, anus, penis or scrotum. They may vary in size and shape and usually appear within weeks or months of sexual contact with an infected person. Ano-genital warts are caused by infection with certain types of the human papillomavirus (HPV). Human papillomavirus is the name of a group of viruses that includes more than 100 different strains or types. Over 30 types of HPV have been shown to be sexually transmitted and infect the ano-genital area. Some types may lead to the development of invasive cervical cancer and other cancers of the anogenital tract (“high-risk types” e.g HPV-16, -18, -31 and -45) and others can cause ano-genital warts (“low-risk types” e.g HPV-6 and HPV-11). Most people who become infected with HPV will not have any symptoms and will clear the infection on their own.

How do you get ano-genital warts?
Ano-genital warts caused by infection with HPV can be transmitted during vaginal, oral or anal sex, or during genital contact with an infected partner. They are highly infectious and approximately two thirds of people who have sexual contact with a partner with genital warts will develop warts.

What complications can result if ano-genital warts are not treated?
Warts usually disappear even if left untreated, but this can take months or even years. On rare occasions ano-genital warts can develop into fleshy, cauliflower-like growths, which may cause obstruction. Additionally, genital warts can sometimes get larger during pregnancy and if in the vagina, may cause problems during delivery. Certain types of HPV have been associated with cervical cancer and other cancers of the anogenital tract, but most women infected with genital warts are at no increased risk of developing cancer.

HPV and cancer
Most genital HPV infections are asymptomatic and transient and will spontaneously resolve without treatment. Although 70% of new genital HPV infections clear within one year, and 91% clear within two years, high risk strains are more persistent than low risk strains. Persistent infection over a number of years to decades may lead to grade 2 or 3 cervical intraepithelial neoplasia (CIN) and cervical cancer.

Persistent infection by high-risk strains is detectable in more than 99% of cervical cancers. Of these high-risk strains, HPV 16 is responsible for more than 50% and HPV 18 for more than 15% of all cervical cancers in Europe.

In addition to persistent infection with high-risk strains of genital HPV, other co-factors appear to be important in the development of cervical cancer, including cigarette smoking, long-term use of oral contraceptives, multiparity, early age at first delivery, immunosuppression and co-infection with Chlamydia trachomatis or herpes simplex virus type 2.

Cervical cancer rarely occurs in women under 30 years and is most common in women over 40 years. On average, 72 women die each year in Ireland as a result of cervical cancer. The average age of these women at the time of death is 56 years. The average age at the time of diagnosis is 44 years.

Can genital HPV infection be prevented?
Individuals can reduce their risk of getting genital HPV infection by changes in sexual behaviour including abstinence from any sexual activity or lifelong monogamy. Reducing the number of sexual partners and the frequency of new partners will also reduce the risk. Condom use reduces the risk of sexual transmission of HPV but does not eliminate the risk.

Cervical screening can detect pre-cancerous lesions and cervical cancer at an early stage when treatment can be successful. In countries where there is an organised cervical cancer screening programme there has been a marked reduction in the incidence of invasive cervical cancer. Vaccines are available which can be used to prevent infections caused by some strains of HPV viruses thereby reducing the risk of cervical cancer.

HPV vaccines
There are currently two vaccines available which protect against the most common HPV strains that cause cervical cancer (16 and 18) and genital warts (6 and 11). The vaccines have been shown to be 99% effective at preventing pre-cancerous lesions associated with HPV strains 16 and 18 in women not already infected with these strains.

Cervarix gives protection against infections caused by HPV strains 16 and 18 (associated with 70% of cervical cancers). Gardasil also protects against infections caused by strains 16 and 18 and in addition covers strains 6 and 11 which cause genital warts. The vaccines do not protect against diseases caused by HPV strains that are already established in an individual. For this reason the vaccine is given before the start of sexual activity.

The vaccines do not contain any live material and so cannot cause infection or disease. There is no thiomersol in the vaccines.

Three doses of the vaccine are given over a period of six months. All three doses should be given within a 12-month period. The vaccines are not interchangeable.

How are ano-genital warts diagnosed?
Diagnosis is usually made on visual examination. However, ano-genital warts may not be easy to recognise or may be in locations where they are difficult to see. Therefore, such examinations are most commonly done at genitourinary medicine (GUM) or family planning clinics. Women with genital warts, should have a regular cervical smear test which looks for changes in the cells of the cervix that could indicate that cells have become pre-cancerous or cancerous. All types of HPV can cause mild smear test abnormalities, which generally do not have serious consequences. However, about ten types can cause the development of cervical cancer on rare occasions. An abnormal Pap smear result may indicate the possible presence of cervical HPV infection. Early detection of abnormal cells is vital for the prevention of cervical cancer and for its effective treatment if cancerous cells are found. In Ireland, it is recommended that all women between the ages of 25 and 60 have regular smear tests.

How are ano-genital warts treated?
Ano-genital warts are treated according to their size and location. Specific medications can be applied to the warts, they can be frozen with liquid nitrogen or removed through burning or laser treatment. There is no cure for HPV infection and warts can recur after treatment. However, most ano-genital warts eventually heal and disappear even if not treated and, in most people, HPV infection clears in time.

Last updated: 22 April 2009