HPV (Human Papillomavirus)

Overview

By Sarah Maurer

Human papillomaviruses (HPVs) are a group of related viruses that infect human epithelial cells. Epithelial cells line body surfaces like the skin, throat, female reproductive tract and anus. They are avascular, meaning they receive nourishment through neighboring cells rather than the blood vessels.

Viruses, including HPV, are primitive microorganisms that reproduce by injecting their genetic information into healthy cells. The infected cells reproduce rapidly, replicating the viruses’ DNA. Usually, the body's immune system detects and destroys these infected cells. Occasionally this doesn't happen, and the infection becomes chronic, or long-term.

There are more than 100 different strains, or types, of HPV. About 40 specifically affect the genital area, including the vagina, vulva, penis, anus, cervix, rectum and scrotum. Genital forms of the disease are sexually transmitted.

HPV is probably best known for causing warts, including genital warts. Most warts are harmless, but they can cause irritation and embarrassment. Skin-to-skin contact with warts can spread the HPV virus to others.

Cervix of uterus highlighted in a cross-section of female reproductive anatomyA few strains of HPV have the ability to cause cancer. These are known as "high-risk" strains. HPV infection is responsible for about 5 percent of all cancers.

Cancer occurs when an HPV infection causes cell abnormalities. Usually these abnormal cells die off. However, long-term infection can lead to more severe, persistent cell changes that develop into precancerous lesions and eventually cancer. Cancer is a condition in which uncontrolled cell growth causes tumors to form and spread through the body.

Almost all cases of cervical cancer are caused by HPV, with two strains (16 and 18) responsible for 70 percent of all cases. (The cervix is the passage between the vagina and uterus). HPV also causes about 85 percent of anal cancers and about half of all vulva, vagina, penis and upper-respiratory cancers. After the initial infection, HPV-related cancer can take up to 20 years to develop.

The genital form of HPV is the most common sexually transmitted infection in the United States. About half of men and 75 percent of women will be infected with HPV at some point in their lives. Each year, about 360,000 people are diagnosed with genital warts and 10,000 women get cervical cancer.

Causes

HPV usually enters the body through small tear in the skin during skin-to-skin contact. Most people with the virus have no symptoms and don't know they're infected. However, they can still spread the virus to others.

Sexually transmitted forms of HPV spread through genital-to-genital contact with an infected person's vagina, penis or anus. The virus can also be spread by mouth-to-genital contact, though this is less common.

In rare cases, HPV can spread from an infected mother to her baby during birth.

Symptoms

Most people with HPV do not know they are infected and never develop symptoms or health problems. Symptoms like warts, genital warts or cell abnormalities may develop many years after the initial infection.

HPV causes many kinds of skin warts, including:

  • Common warts - rough warts on the hands and fingers
  • Plantar warts - hard, grainy warts on the soles of the feet
  • Flat warts - small, raised warts that appear on many parts of the body.

Genital warts may occur alone or in groups. They come in a variety of sizes and textures and may be flat, stem-like or cauliflower-shaped in appearance.

Cellular changes caused by HPV, including precancerous lesions, usually have no outward symptoms and can only be detected by a laboratory test.

Diagnosis and Treatment

A physician usually diagnoses genital warts simply by looking at them. In some cases, when infection is suspected, the doctor applies a weak vinegar solution to the skin in the genital area. This causes HPV-related lesions to turn white and helps detect flat lesions that are difficult to see.

Several tests can help detect and prevent cervical cancer in women. During the Pap test, the doctor scrapes a small clump of cells from the cervix and sends them to the laboratory for analysis. This test detects precancerous cellular changes caused by HPV infection.

DNA testing can now detect high-risk HPV strains in the cervix before they cause cellular changes. It's usually performed in conjunction with a Pap test in women over 30 or in women who have an abnormal or inconclusive Pap test.

There is no treatment for the HPV virus itself. Warts, including genital warts, can often be removed with topical medications, chemical treatments and surgical techniques. It's important to remember that wart removal does not remove HPV from the skin and that the virus can still be transmitted to others.

When detected in time, precancerous lesions caused by HPV can be surgically removed before they develop into cancer. Options include surgical removal and destruction by laser, electricity or freezing.

Even without treatment, most HPV infections clear up on their own within one to two years, and most don't cause health problems. Chronic (long-term) infection with a high-risk strain increases the risk of cancer, especially in people whose immune systems are weakened by certain medications or by infection with HIV/AIDS. Still, less than 50 percent of high-grade (large, advanced) lesions develop into cancer.

Prevention

HPV is such a common virus that it's difficult to avoid altogether. However, the following steps can help reduce your risk:

  • Don't pick at existing warts or bite your nails.
  • Keep feet clean and dry, and wear sandals in locker rooms, pools and public showers.
  • If you are female, get regular cervical cancer screenings as recommended by your doctor.
  • Use latex condoms every time you have sex. Condoms won't prevent all HPV infections, but research suggests they do provide some protection.
  • Use a barrier method like a dental dam during mouth-to-female-genital contact.

Two effective vaccines are available against certain strains of HPV:

  • Gardisil protects against several HPV-related cancers and genital warts and can be given to both men and women.
  • Cervarix protects women against cervical cancer.

Vaccination is routinely given to children ages 11–12. If you're concerned about HPV and weren't vaccinated as a child, ask your doctor about your vaccination options.

Sources

  • "HPV and Cancer." National Cancer Institute. http://www.cancer.gov/cancertopics/factsheet/Risk/HPV. Accessed May 25, 2014.
  • "HPV Infection." Mayo Foundation for Medical Education and Research, 2013. http://www.mayoclinic.org/diseases-conditions/hpv-infection/basics/definition/con-20030343. Accessed May 25, 2014.
  • "Human papillomavirus (HPV)." Centers for Disease Control and Prevention, 2014. http://www.cdc.gov/std/hpv/stdfact-hpv.htm. Accessed May 21, 2014.
  • "Human papillomavirus (HPV)." Planned Parenthood Federation of America, 2014. http://www.plannedparenthood.org/health-topics/stds-hiv-safer-sex/hpv-4272.htm. Accessed May 25, 2014.