HPV infection causes warts. More than 100 varieties of human papillomavirus (HPV) exist.

Different types of HPV infection can cause warts on different parts of your body. For example, some types of HPV infection cause plantar warts on the feet, while other varieties of HPV infection are responsible for the warts that most commonly occur on the face or neck. More than 40 different strains of HPV affect the genital area.

Most HPV infections don't lead to cancer. But some types of genital HPV can cause cancer of the cervix — the passage between the vagina and the uterus. Vaccines can help protect against the strains of genital HPV most likely to cause genital warts or cervical cancer.

In most cases, your body's immune system defeats an HPV infection before it has a chance to create any warts. When warts do appear, they may vary in appearance depending on which variety of HPV is involved:

  • Genital warts. Genital warts may appear as flat lesions, small cauliflower-like bumps or tiny stem-like protrusions. In women, genital warts appear most commonly on the vulva but may also occur near the anus, on the cervix or in the vagina.

    In men, genital warts may appear on the penis and scrotum or around the anus. Genital warts rarely cause discomfort or pain, though they may itch.

  • Common warts. Common warts appear as rough, raised bumps that usually occur on the hands, fingers or elbows. In most cases, common warts are simply a nuisance because of their appearance, but they may also be painful or susceptible to injury or bleeding.
  • Plantar warts. Plantar warts are hard, grainy growths that usually appear on the heels or balls of your feet, areas that feel the most pressure. These warts may cause discomfort or pain.
  • Flat warts. Flat warts are flat-topped, slightly raised lesions darker than your regular skin color. They usually appear on your face, neck or on areas that have been scratched. HPV infections that cause flat warts usually affect children, adolescents and young adults.

Cervical cancer

Most cases of cervical cancer are caused by two specific varieties of genital HPV. These two HPV strains usually don't cause warts, so women often don't realize they've been infected. Early stages of cervical cancer typically cause no signs or symptoms.

That's why it's important for women to have regular Pap tests, which can detect precancerous changes in the cervix that may lead to cancer. The current guidelines recommend that women ages 21 to 29 have a Pap test every three years. Women ages 30 to 65 are advised to continue having a Pap test every three years, or every five years if they also get the HPV DNA test at the same time. Women over 65 can stop testing if they've had three normal Pap tests in a row, or two HPV DNA and Pap tests with no abnormal results.

When to see a doctor

If you or your child has warts of any kind that cause embarrassment, discomfort or pain, seek advice from your doctor.

HPV infection occurs when the virus enters your body through a cut, abrasion or small tear in the outer layer of your skin. The virus is transferred primarily by skin-to-skin contact.

Genital HPV infections are contracted through sexual intercourse, anal sex and other skin-to-skin contact in the genital region. Some HPV infections that result in oral or upper respiratory lesions are contracted through oral sex.

It's possible for a mother with an HPV infection to transmit the virus to her infant during delivery. This exposure may cause HPV infection in the baby's genitals or upper respiratory system.

HPV infections are common. Risk factors for HPV infection include:

  • Number of sexual partners. The greater your number of sexual partners, the more likely you are to contract a genital HPV infection. Having sex with a partner who has had multiple sex partners also increases your risk.
  • Age. Common warts occur most often in children. While plantar warts may occur in adults, they're more likely to initially surface on adolescents or young adults. Genital warts occur most often in adolescents and young adults.
  • Weakened immune systems. People who have weakened immune systems are at greater risk of HPV infections. Immune systems can be weakened by HIV/AIDS or by immune system-suppressing drugs used after organ transplants.
  • Damaged skin. Areas of skin that have been punctured or opened are more prone to develop common warts.
  • Personal contact. Touching someone's warts or not wearing protection before contacting surfaces that have been exposed to HPV — such as public showers or swimming pools — may increase your risk of HPV infection.
  • Oral and upper respiratory lesions. Some HPV infections may cause lesions to form on your tongue, tonsils, soft palate, or within your larynx and nose.
  • Cancer. Most cases of cervical cancer are caused by two specific varieties of HPV. These two strains may also contribute to cancers of the genitals, anus, mouth and upper respiratory tract.

If you think you have an HPV infection, you'll probably first see your primary care doctor. Depending on where your warts are located, you may be referred to a doctor who specializes in disorders of the skin (dermatologist), feet (podiatrist) or reproductive organs (gynecologist or urologist).

What you can do

Before your appointment, you may want to write a list of questions to ask your doctor, including:

  • What's the most likely cause of my symptoms?
  • What kinds of tests do I need?
  • How can I prevent HPV infection in the future?
  • Is there a generic alternative to the medicine you're prescribing me?
  • Are there any brochures or other printed material that I can take with me? What websites do you recommend?
  • Under what circumstances should I plan for a follow-up visit?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask additional questions during your appointment.

What to expect from your doctor

Your doctor is likely to ask you a number of questions, such as:

  • When did you begin experiencing symptoms?
  • What are your symptoms?
  • Where have you noted lesions?
  • Are the lesions painful?

Your doctor may be able to diagnose HPV infection after visual inspection of any warts or lesions.

If genital warts aren't visible, you may need one or more of the following tests:

  • Vinegar (acetic acid) solution test. Your doctor may apply a vinegar solution that turns HPV-infected genital areas white. This may help in identifying difficult-to-see flat lesions.
  • Pap test. Your doctor collects a sample of cells from your cervix or vagina to send for laboratory analysis. Pap tests can reveal abnormalities that may lead to cancer.
  • DNA test. This test can recognize the DNA of the high-risk varieties of HPV that have been linked to genital cancers. The test is conducted on a sample of cells taken from your cervix. It's recommended for women 30 and older in addition to the Pap test.

Warts often go away without treatment. But even if your warts have disappeared or have been removed, you can still harbor HPV and may transmit the virus to others.

Medications

Medications to eliminate warts are typically applied directly to the lesion and usually take many applications before they are successful. Examples include:

  • Salicylic acid. Over-the-counter treatments that contain salicylic acid work by removing layers of a wart a little bit at a time. Salicylic acid is for use on common warts. It can cause skin irritation and isn't for use on your face.
  • Imiquimod (Aldara, Zyclara). This prescription cream may enhance your immune system's ability to fight HPV. Common side effects of imiquimod include redness and swelling at the application site.
  • Podofilox (Condylox). Another type of topical prescription, podofilox works by destroying genital wart tissue. Podofilox may cause pain and itching where it's applied.
  • Trichloroacetic acid. This chemical treatment burns off genital warts and may cause local irritation.

Surgical and other procedures

If medications don't work, your doctor may suggest one of the following procedures, which physically remove warts by:

  • Freezing with liquid nitrogen (cryotherapy)
  • Burning with an electrical current (electrocautery)
  • Surgical removal
  • Laser surgery

It's difficult to prevent HPV infections that cause common warts. If you have a common wart, you can prevent the spread of the infection and formation of new warts by not picking at a wart and not biting your nails.

Plantar warts

You may reduce the risk of contracting HPV infections that cause plantar warts by wearing shoes or sandals in public pools and locker rooms.

Genital warts

You can reduce your risk of developing genital warts and other HPV-related genital lesions by:

  • Being in a mutually monogamous sexual relationship
  • Reducing your number of sex partners
  • Using a latex condom, which may prevent some but not all HPV transmission

HPV vaccines

A vaccine known as Gardasil protects against the strains of HPV that cause most genital warts. Gardasil also protects against the HPV strains most likely to cause cervical cancer. Another vaccine, called Cervarix, protects against cervical cancer but not genital warts.

The Centers for Disease Control and Prevention (CDC) recommends routine HPV vaccination for girls and boys ages 11 and 12. The vaccines are to be administered in three doses over six months. If children are not fully vaccinated at ages 11 and 12, the CDC recommends that girls and women through age 26 and boys and men through age 21 receive the vaccine. However, men may receive the HPV vaccine through age 26 if desired.

The CDC also recommends the vaccine through age 26 for men who have sex with men and for both men and women who are immune compromised if they didn't get the vaccine when younger. However, these vaccines are most effective if given before becoming sexually active.

The vaccines haven't yet been available for 10 years, but early research has already shown declining levels of genital warts. There has also been a reduction in the number of abnormalities found in cervical tissue that indicate an HPV infection.

Researchers are already working on newer vaccines that include more strains of HPV.

Sep. 16, 2014