Genital warts are the most common viral STI in the UK, with highest rates of new cases in 20-24-year-old men and 16-19-year-old women. There are approximately 40 types of HPV which can infect the genital tract.
Genital HPV infections are frequently asymptomatic (subclinical) and resolve without causing obvious lesions but may be transmitted to a sexual partner who may develop macroscopic warts.
Transmission is through close physical (skin to skin) contact, almost always genital for genital warts. Auto-innoculation from other sites is very unusual. The incubation period for warts is usually three to 18 months but can be longer.
1. Clinical features
Patients with external genital warts do not generally have any associated symptoms apart from occasional itch and will usually present because they have noticed or felt growths.
The warts may occur anywhere in the genital area, irrespective of sexual practices.
In men, warts are commonly found on the penis and/or the proximal urethra and meatus, the perianal region and, less commonly, the perineum and scrotum.
In women, warts are most commonly found on the vulva, perineum, perianal area, cervix and, less commonly, the vagina and urethra.
The warts may be keratinised or soft, and range from solitary and tiny to multiple and large. They may be pigmented. Bleeding is uncommon except with meatal warts. Often HPV infection is subclinical and patients will be unaware of their infection.
2. Complications and associations
External genital warts are most commonly caused by HPV types 6 and 11, which are rarely associated with severe dysplasia and do not cause genital or anal cancers.
Genital warts and dysplasia are more pronounced in patients with immunodeficiency, for example in HIV infection, or iatrogenic immunosuppression, such as in renal transplantation.
Several genital strains are oncogenic and may be associated with abnormal cervical smear tests. These strains rarely cause visible warts, but these women will be detected through the national cervical screening programme.
Some patients present for the first time in pregnancy and warts may be more difficult to treat during pregnancy. In addition, certain topical therapies are contraindicated in pregnancy.
The risk of vertical transmission appears to be very low and on the basis of current evidence the presence of genital warts should not influence the management of delivery. Spontaneous resolution in the puerperium may occur.
3. Diagnosis
The diagnosis is clinical and based on the characteristic appearance of genital warts on visual examination under good light. There is no place for HPV typing in routine clinical practice.
A biopsy should be taken if there is any doubt about the diagnosis (for example, if there is pigmentation, ulceration or other atypical characteristics).
Up to 20 per cent of patients presenting with first-episode genital warts have other STIs so full screening for STIs is recommended.
4. Treatment
Anogenital warts are essentially a cosmetic problem but often cause patients considerable psychological and psychosexual distress. The aim of treatment is to eradicate visible warts by destroying the affected tissue.
With the currently available therapies, eradication of the virus is not guaranteed and recurrences are common. It is important to explain to patients that they may remain infectious even in the absence of visible warts. Recent studies suggest that the majority of patients are clear of the virus within 12 months of acquisition.
At any stage individuals may be referred to the local GUM department for initiation of treatment, joint ongoing management, screening for other STIs, recalcitrant cases or complicated cases.
Treatments available in primary care include podophyllotoxin and imiquimod, which are both suitable for home treatment by patients. The patient should be given a demonstration on lesion finding and treatment application.
Podophyllotoxin is available as a cream, which may be easier for patients to apply, or a solution. It is applied in cycles of twice daily application for three days, followed by four days rest for four to five cycles. It should be avoided in pregnancy.
Imiquimod 5% cream is not recommended for use in pregnancy or internally. Cream is applied to lesions three times per week and washed off six to 10 hours later for up to 16 weeks. Response to treatment may be delayed for some weeks. Weekly cryotherapy can be used if available and it is safe in pregnancy.
Patients should be monitored during treatment to check for efficacy and non-response (in which case treatment should be changed). Recurrence rates are high and multiple rounds of treatment may be required.
5. Contact tracing
All contacts should be offered STI screening and advice about HPV. Sometimes contact tracing will identify patients with previously unrecognised warts. If warts are not present they can be advised that most patients developing warts as a result of recent contact do so within several months. The current local policies for cervical smear recall should be followed for all female HPV contacts.
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- Further reading www.bashh.org (UK Management guidelines)
- Dr Sherrard is a consultant GUM physician at Oxford Radcliffe NHS Trust.
