Genital warts HPV

Organism

Genital warts are caused by the human papilloma virus (HPV). There are over 200 subtypes of the virus of which over 25 cause genital infection.

HPV infections of the genital epithelium are thought to be sexually transmitted and are classified as oncogenic (cancer forming or high-risk) (commonly caused by types 16 and 18) and non-oncogenic (low-risk) (commonly caused by types 6 and 11). Infection with the low-risk types is associated with the formation of genital warts.

Cervical cancer is now known to be caused by oncogenic strains of HPV. It is thought that cervical cancer is preceded by the development of high-grade cervical dysplasia, and that cervical cancer can be prevented by removal of these high-grade lesions. People who develop genital warts may acquire an oncogenic strain of HPV at the same time. Low-grade dysplasia may be caused by either an oncogenic or non-oncogenic strain, or both.

The incubation is 2-3 months although it can range from 1-20 months. The period of communicability is probably at least as long as visible lesions persist. Contact infectivity is high if lesions are present but lower if there are no lesions.

Clinical presentation

The majority of newly acquired HPV infections appear to be subclinical and asymptomatic. Clinically visible manifestations of HPV include warts that may be condylomatous, papular, flat or keratotic in appearance.

Investigations

Essentially, diagnosis of warts is clinical. Tests to detect the high-risk viruses are now available but not yet for routine use. Adjunctive HPV DNA testing of the cervix, performed at the time the Pap smear is taken, may facilitate patient management in the future. Acetic acid testing, in an attempt to demonstrate areas of external genital HPV infection, is not reliable.

Treatment

Treatment of genital warts is encouraged as they are highly infectious. In addition, if left untreated, the warts may enlarge. However, recurrence is common. Up to 50 per cent of cases have recurrence within the first 6 months following treatment. First line therapy is usually with patient self-applied podophyllotoxin or provider-applied cryotherapy. Advise patients not to shave the pubic area as this spreads the infection.

  • Apply podophyllotoxin paint (0.5 per cent, 3.5 mL) (not on PBS) twice daily for three days, and then do not treat for four days. Continue the seven-day cycle for up to four weeks. Some patients may not be able to tolerate this intensity of treatment and reduced frequency is required.
  • Apply podophyllotoxin cream (0.15 per cent) topically twice daily for three days, and then do not treat for four days. Continue the seven-day cycle for up to four weeks.
  • Cryotherapy: apply liquid nitrogen to visible warts weekly until resolution occurs.
  • Surgical ablative therapy may be indicated for extensive lesions. It is useful for single large warts and requires local anaesthesia. Care should be taken to ensure the warts are not condylomata lata of secondary syphilis or donovanosis where, in both cases, antibiotic therapy is the appropriate treatment.
  • Apply imiquimod 5 per cent cream topically, 3 times a week for up to 16 weeks (not on PBS).
  • Biopsy of atypical or longstanding lesions is recommended to exclude dysplasia, especially in HIV-infected individuals.
  • Cervical warts should always be referred to sexual health physicians or gynaecologists for further investigation.

Pregnancy

Precaution

Podophyllotoxin and imiquimod should not be used in pregnancy or breastfeeding.

Related links

Management of partners

Current sexual partners may benefit from assessment as they may have undetected genital warts or other STIs, or they may need an explanation and advice about the disease process in their partner. Female partners of men with genital warts should be encouraged to have Pap smears if they are not already having regular two yearly Pap testing.

Patients should be advised to use condoms until treatment is completed, or with new sex partners.

Follow-up

The patient should be assessed clinically to assess response to therapy, and retreated as required.

Always test for other STIs.

Public health issues

This is not a notifiable disease.

If a child is diagnosed with an STI, issues of sexual abuse and/or sexual assault should be considered. However, warts in the genital area in a child can be spread from other sites through autoinoculation. Women with genital warts, or female partners of patients with genital warts, should be encouraged to have regular Pap smears.