Introduction
Human Papilloma Virus is an extremely common virus that can infect the skin and musical surfaces – including of the mouth, respiratory tract and anogenital region.
There are over 100 types of HPV infection. Most of these are completely harmless and asymptomatic and infections are usually self-limiting. A small number of type of the virus can cause genital warts, or ano-genital cancers, or penile cancer. HPV is clinically most important due to its association with cervical cancer.
Genital HPV is transmitted via sexual contact. Condoms reduce but do not eliminate the risk entirely.
HPV types 16 and 18 are responsible for about 66% of cervical cancers, and more than 80% of anal cancers globally, although the total number of anogenital and penile cancers is low. These types of HPV are often referred to as “high risk” HPV. Type 11 and about 10 other types are associated with genital wart.
- The majority of infections are cleared within a few weeks
- Persistent infection is associated with cancer
- HPV vaccination protects against type 16 and 18 (this is usually given to teenagers around the age of 13 and is part of the routine vaccination schedule in Australia and the UK). Some newer vaccines also protect against additional strains (particularly HPV 11, and the other strains that cause warts – e.g. Gardasil 9(R).
- HPV vaccination greatly reduces the risk of developing future cervical cancer (>99% efficacy)
Genital warts due to HPV can be difficult to treat, but most cases will resolve sporadically eventually. There can be a very long latency period between contracting the virus and warts appearing – new onset warts does not necessarily imply a newly contracted infection.
Unless otherwise specified – the rest of this article is concerned with the genital warts. For more information about cervical cancer and CIN – go here.
Epidemiology
- The most common STI in the UK
- Estimated that 10-20% of the population have a genital HPV infection, but only 1% of the population are symptomatic at any one time
- Very low prevalence amongst those aged 14 – rises sharply around the mid teens
- HPV is detected in 99% of cervical tumours
- HPV types 6 and 11 account for >90% of cases of warts
Spread
- Usually by sexual contact
- Can be spread via oral sex (in both directions!), although less common than intercourse spread
- Incubation period is usually a matter of weeks, but may be months, or even years
- The partner (Source of infection) may not have any visible lesions
- 70% risk of transmission if unprotected sex with infected partner
Presentation
- Most cases asymptomatic
- Skin lesions may be present on the penis, vulva, anus, vagina, perineal or perianal region. They can also be found inside the anus and urethra.
- Look a little bit like skin tags
- Tend to form in clusters
- Usually painless, but may be itchy
- May or may not be pedunculated
- Slightly less common in men
- Usually on the penis in men, not other areas
- Rarely may occur around / in mouth due to oral contact
Management
- Many cases may resolve spontaneously
- Typically, the longer a symptomatic infection is present, the larger the growths
Treat both the patient and their partner.
- Also consider cervical screening in any woman who has not recently had one
Podophyllin Paint
- Can be applied weekly in clinic to the affected area. If widespread, don’t treat all warts at once to avoid toxicity.
- Leave for 30m then wash off
- Avoid in pregnancy
Podophyllotoxin cream
- Can be applied by the patient at home every 12h for 3 days
- Repeat weekly if necessary
Imiquimod cream
- 5% imiquimod cream topically
- 3x per week at bedtime
- Wash off after 6-10 hours
- Can use for up to 16 weeks
Cryocauterisation
- Freezing off the warts – usually with nitrogen
- May be used in conjunction with podophyllin paint at clinic sessions
- Often used as solitary treatment during pregnancy
- About 70% effective, but up to 60% of cases will reccurr within 6 months
Diathermy / surgical excision
- Cauterise them off with a hot wire, or cut them off with a scalpel
- Rarely used
- Frequently recur
- Can be painful and cause scarring
Laser therapy
- Not widely used
- No more effective than other removal techniques
- Expensive
These last three methods may be uncomfortable, but are generally not painful. If persistent, these methods will generally remove any visible warts, but they can recur at any stage.
The patient is also infective during asymptomatic periods – however, they are more infectious when visible lesions are present.
References
- Australian STI guidelines – anogenital warts
- Human papilloma virus – patient.info
- Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
- Oxford Handbook of General Practice. 3rd Ed. (2010) Simon, C., Everitt, H., van Drop, F
- Beers, MH., Porter RS., Jones, TV., Kaplan JL., Berkwits, M. The Merck Manual of Diagnosis and Therapy