Human papillomavirus

September 14, 2011

Human papillomavirus (HPV) infection may be the most common viral sexually transmitted disease (STD) in this country. As many as 30 million Americans are infected with Human papillomavirus, and each year, an additional 1 million people become infected.

More than 80 distinct types of Human papillomavirus have been identified; at least 20 of them can infect the genital tract. Infection due to Human papillomavirus types 6 or 11 is usually associated with external genital warts, such as condylomata acuminata, whereas those due to Human papillomavirus type 16 or 18 are associated with cancers of the genitals (cervical, vulvar, and anal carcinomas).

Human papillomavirus infection likely begins with an abrasion or cut of the epithelium (skin, outside or inside). The wound provides viral access to the skin. During wound healing cell division accelerates, which may actually facilitate viral replication.

After introduction of the virus into the body (inoculation), an incubation period begins and lasts from 4 weeks to 8 months. The incubation is followed by an active expression phase. This phase is marked by rapid capillary proliferation (increase in small blood vessels) that usually persists from 3 to 6 months. It is during this phase that obvious growths (lesions) emerge or subclinical (one that cannot be seen) lesions develop.

Approximately 3 months after the initial proliferative phase and appearance of lesions (visible or not), an immune response can be detected. The result of the patient’s immune response is a suppression of new lesions. This is known as the host containment phase. It is known that an intact immune system is at least as important as any available therapies for Human papillomavirus infection in resolving the clinical manifestations of this disease.

After about 9 months, a latent phase begins. This phase is characterized either by continued clinical remission or by a continued active disease. If the active disease is continuing it may place the patient at risk for neoplasia (new growths or abnormal cell development (dysplasia) or cancer). In some patients, particularly younger women, the infection may resolve.


Genital Human papillomavirus infection is transmitted by intimate sexual contact. Early age at first intercourse, multiple sexual partners, and intercourse with a person who has external genital warts are risk factors for Human papillomavirus infection. Smoking also increases risk. Although intra-anal warts are associated with anal (anoreceptive) intercourse, warts around the anus (perianal warts) are not.

Transmission of Human papillomavirus from mother to infant is uncommon. Delivery by cesarean section, if not indicated for obstetrical reasons, is not recommended for infected women unless external genital warts are obstructing the birth canal.


Clinical exam has been proven a reliable method for establishing a diagnosis of genital warts; however, Human papillomavirus can cause warts to form in the vagina, on the uterine cervix, and inside the urethra and anus. In many cases only cervical cytology (Pap smear) can pick up the characteristic cellular changes causing the Pap smear to be abnormal. It is the most common method of detecting subclinical disease. Sometimes biopsy should be performed when diagnosis is in doubt or when despite treatment, the disease worsens, or the patient has a weakened immune system (immunocompromised) or skin/warts are pigmented, feel hard, immobile, or ulcerated.

Women with Human papillomavirus infection (and their sexual partners) should be examined for other STDs. Tests for the common STDs, syphilis, gonorrhea, and chlamydia; should be considered. Routine screening for cervical cancer should be performed annually; more frequent Pap tests are not required by a diagnosis of external genital warts, but should be performed if cervical dysplasia (abnormal cells) is noted on the Pap smear.


The primary goal of treatment is to either remove symptomatic warts or destroy the dysplastic process actively or allowing patients’ own immune system to destroy the lesions. It is important for the patient to understand that whether the external warts or dysplasia is resolved the Human papillomavirus virus remains in the patient. This fact is a source of much consternation and must be understood. Although proper treatment may produce lesion-free periods, no evidence exists that any available therapy can eliminate the infection. As many as 21% of vulvar warts (warts on the outer parts of the vagina) resolve without treatment and up to 70-75% of Pap smears with mild dysplasia in the younger women will resolve in 1 year without treatment. The patient should be educated and involved in her treatment. No single therapy is ideal for all women or all lesions, warts, or abnormal Pap smears. Smoking cessation is strongly recommended.

If the patient is pregnant, external warts may be removed by bichloroacetic acid (BCA) or trichloroacetic acid (TCA) cryotherapy (freezing therapy) or surgical excision. If the patient is not pregnant, podophyllin, imiquimod (Aldara), or interferon may be used. It is important to use these medications just as prescribed since soreness and pain commonly occur with overuse. Once lesions are gone, therapy may be stopped. For the abnormal Pap smear, mild dysplasia may be followed as it will be resolved in approximately 70-75% of the time after being followed over a year. If the patient is not comfortable with observation, cryosurgery may be used. If more advanced lesions are present, more advanced surgical removal techniques such as LEEP or cold knife conization may be utilized on a case-by-case basis depending on where the dysplasia is located. Discussion between the patient and physician is imperative.

A follow-up evaluation after visible genital warts have cleared is not necessary. Patients should be advised to watch for recurrences that develop most frequently during the first 3 months. However, follow-up visits may be useful for documenting a wart-free state, monitoring treatment compliance and complications, and providing patient education and counseling. The presence of external genital warts is not an indication for colposcopy (specialized examination procedure using a small tube) of the cervix or for more frequent Pap smears unless the patient has abnormal Pap smears.

Examination of the sex partners of Human papillomavirus-infected women is not necessary for the management of their external warts because the role of reinfection in persistent disease is probably minimal. However, such examination is recommended to detect other STDs or previously unrecognized visible warts. Use of condoms can reduce but not eliminate transmission of Human papillomavirus to uninfected partners. Patients should understand that they may remain infectious even after their visible warts have resolved.

SEE ALSO: Cervical cancer, Chlamydia, Colposcopy, Condoms, Sexually transmitted diseases

Suggested Reading

  • Eng, T. R., & Butler, W. R. (Eds.). (1997). Confronting sexually transmitted diseases. Report by a committee of the Institute of Medicine, Board on Health Promotion and Disease Prevention. Washington, DC: National Academy Press.


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