Sexually acquired human papillomavirus

What is human papillomavirus?

Human papillomavirus (HPV) is a DNA virus of the papillomavirus family. It is also known as the wart virus.

HPV infects the epidermal cells that form the skin, and the epithelial cells that form the anogenital tract and upper respiratory tract. Eight in every ten individuals are estimated to have contracted HPV at some point in their lifetime.

The HPV family has been classified into more than 170 subtypes (each denoted by a number).

• HPV types 1, 2, 4 and 7 are associated with common warts.
• HPV 3 and 10 are associated with plane warts.
• HPV 1, 2, 4, 60 and 63 are associated with plantar warts.
• HPV 5 is associated with warts in epidermodysplasia verruciformis(a rare skin condition).
• HPV 6 is associated with genital, oral and laryngeal warts.

Common warts

Filiform wart

Plantar wart

What is sexually acquired human papillomavirus?

Various subtypes of HPV preferentially infect epithelial cells and tend to be sexually transmitted.

Low-risk subtypes of HPV, such as types 6 and 11, are asymptomatic or cause anogenital warts and squamous cell papillomas.

There are approximately 13 high-risk subtypes of sexually transmitted HPV. In some cases, these present with precancerous squamous intraepithelial lesions and cancer (squamous cell carcinoma).

Anogenital wart

Anogenital wart

Anogenital wart

Who gets sexually acquired human papillomavirus?

Sexually acquired HPV infects both men and women. The highest risk of acquiring HPV is soon after sexual debut. 

Risk factors for infection include:

• Early age of intercourse
• Multiple sexual partners
• Smoking
• Immunosuppression.

How does human papillomavirus spread?

HPV is typically spread via skin to skin contact during vaginal and anal sexual intercourse. HPV can also occasionally be transmitted vertically, from mother to child during birth.

What are the clinical features of human papillomavirus infection?

Cutaneous HPV infection

Cutaneous HPV presents as:

• Epidermodysplasia verruciformis
• Intraepidermal squamous cell carcinoma in immunosuppressed individuals, such as organ transplant recipients
• Viral warts are non-cancerous skin growths with a hard surface; there are many types, including:
  • Common warts — usually affect hands, fingers and elbows
  • Plantar warts — affect the soles of the feet
  • Plane warts — these have a flat surface and affect the face, shins and back of hands.

Epithelial HPV infection

Although HPV is the most common sexually transmitted virus, the virus is symptomless in most individuals and the infection resolves by itself.

The persistence of certain subtypes of HPV leads to:

• Benign cellular changes noted on histopathology
• Genital warts
• Squamous papillomas in the oropharynx, nasal passages and larynx.

What are the complications of high-risk human papillomavirus infection?

High-risk subtypes HPV 16 and HPV 18 are thought to be responsible for 70% of precancerous and cancerous disease.

Squamous intraepithelial lesions (SILs), also known as intraepithelial neoplasia (IN), are classified by the affected site. Types of SIL include:

• Cervical intraepithelial neoplasia (CIN)
• Vulval SIL or vulval intraepithelial neoplasia (VIN)
• Vaginal SIL or vaginal intraepithelial neoplasia (VAIN)
• Penile SIL or penile intraepithelial neoplasia (PIN)
• Anal SIL or anal intraepithelial neoplasia (AIN)
• Oropharyngeal SIL or oral leukoplakia
• Nasopharyngeal SIL.

HPV is also associated with squamous cell carcinomas of the anus and anal canal, oropharyngeal tract (oral cancer), vagina, vulva and penis. The most common invasive cancer associated with HPV is cervical cancer.

Vulval high-grade squamous intraepithelial lesion

Penile high-grade squamous intraepithelial lesion

Perianal high-grade squamous intraepithelial lesion

How is human papillomavirus infection diagnosed?

An HPV infection is diagnosed clinically. Genital warts caused by HPV infection show a characteristic presence of koilocytes and can be identified by skin biopsy. Double nuclei may be seen, and the nuclei are often hyperchromatic.

Other methods of diagnosing HPV infection include:

• Viral DNA detection methods
• Colposcopy and acetic acid test, used for examination of the cervix and vagina
• Biopsy, which is performed during a colposcopy if abnormal areas are indicated.  

What is the treatment of sexually acquired human papillomavirus infection?

HPV cannot be eliminated, as it incorporates into the genome of the epithelial cells. However, result warts, precancerous and cancerous lesions can be removed.

Treatments may include:

• Cryotherapy
• Topical therapy, such as podophyllotoxin or imiquimod cream. Podophyllotoxin is cytotoxic, hence it should not be used in pregnancy
• Laser treatments
• Surgery, such as electrosurgery, where the base of the growth is burned under local anaesthetic.

Can sexually acquired human papillomavirus infection be prevented?

Condoms are an important means to reduce the transmission of HPV. However, they do not completely eliminate the risk.

Most cases of sexually acquired HPV infection can now be prevented by vaccination during childhood before the onset of sexual activity.