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Genital Warts (Human Papillomavirus)

Topic Overview

Is this topic for you?

This topic provides information about the human papillomavirus (HPV), which causes genital warts and can also cause cervical cancer. If you are looking for information about cervical cell changes or cervical cancer, see the topics Abnormal Pap Test or Cervical Cancer.

What is human papillomavirus (HPV)?

Human papillomavirus (HPV) is one of the most common sexually transmitted infections (STIs). It is a virus that can be spread through skin-to-skin contact. There are many different types of HPV. Some types cause genital warts and are called low-risk, and some types can lead to cervical cancer and are called high-risk. There is no known cure for HPV, but there is a vaccine that can protect against some types of the virus.

What are genital warts?

Genital warts are skin growths in the groin, genital, or anal areas. They can be different sizes and shapes. Some look like flat white patches, and others are bumpy, like tiny bunches of cauliflower. Sometimes you can't see the warts at all.

What causes HPV and genital warts?

HPV is a virus. Certain types of the virus cause genital warts and some types cause abnormal cervical cell changes and cervical cancer.

HPV and genital warts can be spread through sexual contact with someone who has the virus.

What are the symptoms?

Most people infected with HPV don't have symptoms. But if they do, the symptoms may be so mild that they may not know they are infected. The symptoms may include pain, itching, and bleeding, or you may develop visible genital warts.

If you have symptoms, they will probably occur 2 to 3 months after infection. But you can have symptoms from 3 weeks to many years after infection.

Visible genital warts appear only during active infection. But it is possible to spread the virus even if you can't see the warts.

How are HPV and genital warts diagnosed?

A doctor can often tell if you have genital warts by looking closely at your genital and anal areas. He or she may ask you questions about your symptoms and your risk factors. Risk factors are things that make you more likely to get a disease.

Sometimes the doctor takes a sample of tissue from the wart for testing.

For women, if you have an abnormal Pap test, your doctor can do an HPV test that looks for high-risk types of the virus.

How are they treated?

There is no cure for HPV, but the symptoms can be treated.

Talk to your doctor about whether you should treat visible genital warts. They usually go away with no treatment, but they may also spread. Most people decide to treat them because of the symptoms or because of how the warts look. But if you don't have symptoms and are not worried about how the warts look, you can wait and see if the warts go away.

If you do decide to treat genital warts, talk to your doctor about the best treatment for you. There are prescription medicines you or your doctor can put on the warts. Or your doctor can remove them with lasers, surgery, or by freezing them off.

Even if you treat visible warts or your warts go away without treatment, the HPV infection can stay in your body's cells. It is possible to spread genital warts to your partner even if you have no signs of them.

Can HPV and genital warts be prevented?

The best way to keep from getting genital warts—or any other STI—is to not have sex. If you do have sex, practice safe sex.

  • Use condoms. Condoms may help reduce the risk of spreading genital warts, but they do not protect the entire genital area against skin-to-skin contact.
  • Before you have sex with someone, talk to them about STIs. Find out whether he or she is at risk for them. Remember that a person can be infected without knowing it.
  • If you have symptoms of an STI, don't have sex.
  • Do not have sex with anyone who has symptoms or who may have been exposed to an STI.
  • Do not have more than one sex partner at a time. Having several sex partners increases your risk for disease.

If you are age 26 or younger, you can get the HPV shot. The vaccines Cervarix(What is a PDF document?) and Gardasil(What is a PDF document?) protect against two types of HPV that cause cervical cancer. Gardasil also protects against two types of HPV that cause genital warts.

Frequently Asked Questions

Learning about genital warts:

Being diagnosed:

Getting treatment:

Ongoing concerns:

Living with genital warts:

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  HPV: Should My Child Get the Vaccine?

Cause

HPV infection is caused by a virus. More than 100 types of HPV have been found. Some types cause genital warts and some can lead to cervical cancer. Types 6 and 11 cause most genital warts. Other types such as 16 and 18 are high-risk and can cause abnormal cell changes on the cervix.

How the disease is spread (transmission)

HPV is spread by direct contact.

  • The virus can be spread to or from the genitals, anus, mouth, or throat during sexual activities. But warts in the mouth or throat are extremely rare. Condoms can lower your risk of getting genital warts. You can prevent infection when you use them every time you have sex.
  • After the infection occurs, it may spread to other areas of the genitals or to the anal area.
  • You can spread the virus even if you do not have any symptoms of infection or any visible warts.
  • There is a small chance that a pregnant woman can pass the virus to her baby. It is unknown if it is spread during vaginal delivery or if it is spread during the pregnancy. Most women with genital warts do not need to have a cesarean delivery. But your doctor might recommend a cesarean delivery if the genital warts would be in the way or bleed a lot during vaginal delivery.1
  • Children can get genital warts from sexual abuse.

Symptoms

Human papillomavirus (HPV) infection

Infection with the human papillomavirus (HPV) usually does not cause any symptoms and does not always produce visible genital warts. Some types of HPV cause cell changes to the cervix that can cause an abnormal Pap test.

When symptoms do develop, they usually occur 2 to 3 months after infection. But symptoms have been known to occur from 3 weeks to many years after infection.

Symptoms that may occur with genital warts include:

  • Irritation.
  • Itching.
  • Bleeding.

Genital warts

Genital warts can be different sizes and shapes.

  • They may be large, or they may be too small to be seen with the naked eye. They may appear individually or in groups.
  • Warts may look like tiny bunches of cauliflower or like flat, white areas that are very difficult to see.
  • In women and men, warts may appear in the groin, on and around the genitals, in the urethra, or in the rectum or anus.
  • In women:
    • Genital warts may appear on the vulva, vagina, or cervix.
    • Women are often unaware of warts inside the vagina or on the cervix until a doctor finds them.
  • In men:
    • Genital warts may occur on the outside of the penis and scrotum.
    • Men are often unaware they have genital warts, even when they can be seen, until the warts are identified by a doctor.
Symptoms of genital warts may be similar to those of other conditions.

What Happens

Based on the type of HPV, you may or may not have visible genital warts.

  • Common HPV types 6 and 11 produce visible warts. These warts may go away on their own, stay the same, or increase in amount.
  • Other HPV types, such as 16 and 18, do not produce visible genital warts. These types, which may be found with a Pap test, are associated with precancerous cervical cell changes and cervical cancer.

HPV infection and cervical cell changes

In women, most precancerous or cancerous cell changes associated with HPV infection occur on the cervix. This is because the cells of the cervix naturally undergo changes in an area called the transformation zone. This process can cause cervical cells to become abnormal when they are infected with HPV.

Infection with high-risk types of HPV increase the chance that a woman with HPV will develop abnormal cervical cell changes. It is important to have regular exams by your doctor. If your doctor finds abnormal cells on a Pap test, the cells can be treated to help prevent them from changing to cancer.

HPV infection during pregnancy

The presence of HPV and abnormal cell changes does not affect the outcome of the pregnancy. A pregnant woman infected with the type of HPV that causes genital warts may have more complicated warts than a woman who is not pregnant. Genital warts may increase in size, bleed, or become infected with bacteria. Your doctor may recommend treatment. Warts may be passed on to the newborn, but this is rare.

HPV infection and cancer in men

It is not clear whether men who are infected with HPV on the penis are more likely to have precancerous or cancerous changes on the penis than men who are not infected. Because HPV does cause cell changes, more research is being done to find out whether HPV increases the risk of penile cancer. In the United States, cancer of the penis is extremely rare.

Among men who receive anal sex, HPV infection of the anal canal is associated with an increased risk of anal cancer. This risk may be especially high in men who also have HIV infection.2

What Increases Your Risk

Factors that increase the risk of becoming infected with a sexually transmitted infection, such as HPV and genital warts, include:

  • Having multiple sex partners.
  • Having high-risk partner(s) (partner has multiple sex partners or HPV-infected sex partners).
  • Having unprotected sexual contact (not using condoms).
  • Having an impaired immune system.

If you have a high-risk type of HPV and are using birth control pills for more than 5 years, research suggests that this can increase your risk of getting cervical cancer.3 More research is needed, but for more information, see the topic Cervical Cancer.

When To Call a Doctor

Call your doctor if you have any of the following symptoms:

  • Sores, bumps, rashes, blisters, or warts on or around your genitals or anus
  • Burning, pain, or severe itching while urinating
  • For women, an abnormal vaginal discharge that smells bad
  • For men, an abnormal discharge from your penis

Call your doctor if you suspect you have been exposed to a sexually transmitted infection (STI).

Avoid sexual contact until you have been examined by a doctor.

Children

A child can get genital warts in several ways. Any child with genital warts needs to be evaluated by a doctor to find out the cause and to assess for possible sexual abuse.

In rare cases, infants may develop warts in the larynx (laryngeal papillomas), which is in the throat, from exposure to HPV during birth.

Watchful waiting

A doctor should evaluate any warts or other symptoms that suggest infection with the human papillomavirus (HPV) or another sexually transmitted infection (STI). Avoid sexual contact until you have been examined. If you have an STI, avoid sexual contact to prevent spreading the virus.

Sometimes, warts may go away on their own. If you have genital warts, your doctor may observe your condition without using medical treatment. This is called watchful waiting. This period may vary from a few days to weeks or possibly months.

The length of the watchful waiting period is based on:

  • The severity of your symptoms.
  • The progression of the problem if not treated.
  • The risks and benefits of waiting.
  • Your age and medical history.

Who to see

In general, your family doctor or any of the following health professionals can determine whether you have genital warts:

Treatment may require a specialist, such as a:

To prepare for your appointment, see the topic Making the Most of Your Appointment.

Exams and Tests

A doctor usually can diagnose visible genital warts using your medical history and a physical exam. But not all HPV infections cause visible warts. If you don't have any visible genital warts or other symptoms, it may be hard for your doctor to diagnose HPV infection. Your doctor may ask you the following questions:

  • Do you think you were exposed to HPV or any sexually transmitted infections (STIs)? How do you know? Did your partner tell you?
  • What are your symptoms? If you have discharge from the vagina or penis, it is important to note any smell or color.
  • Did you use condoms to protect against STIs?
  • Which sexual behaviors do you or your partner engage in, including high-risk behaviors such as sex with multiple partners?
  • Have you had an STI in the past? How was it treated?
  • Have you ever had an abnormal Pap test (for women)?

For women

After your doctor takes your medical history, you will have a gynecological exam, which usually includes a Pap test.

A Pap test screens for abnormal cells on the cervix. Results of the Pap test may indicate an HPV infection even though you have no visible warts.

Women over 30 may get a screening test for HPV at the same time as a Pap test. This HPV test looks for the DNA (genetic information) of the virus. Women under 30 usually get the HPV test only if they have an abnormal Pap test.4

If your doctor finds areas of abnormal tissue on the cervix (which may be related to HPV infection), he or she may recommend treatment.

For men

After the medical history, you will have a physical exam for genital warts.

There is no screening test for HPV infection in men. But even though there are no formal guidelines, some experts believe that men who receive anal sex should have a routine anal Pap test, especially if they also have HIV infection. Ask your doctor whether and how often you should be tested.

For men and women

If visible warts are present, a diagnosis can usually be made without more testing.

When your doctor finds abnormal tissue but cannot make a definite diagnosis, you may have a biopsy for lab tissue studies.

Testing for the type of HPV that is causing warts is not useful for diagnosis. This test is not routinely done for diagnosis or treatment of genital warts.

Treatment Overview

There is no cure for HPV, but warts and cell changes can be treated. HPV infection that causes an abnormal Pap test will be treated differently than the HPV types that cause genital warts.

Genital warts caused by the most common types of human papillomavirus (HPV) may go away on their own without treatment. For this and other reasons, experts sometimes have different approaches to treating genital warts.

  • Genital warts may disappear without treatment. This is the natural course of many genital warts.
  • Destroying large areas of warts is difficult and may cause scarring.
  • Treatment for genital warts does not eliminate the HPV infection. You may still be able to spread the infection. Condoms can help reduce the risk of HPV infection.
  • Treatment of genital warts can be painful, and warts may return after treatment. Warts that return after being treated usually are not treated again unless you want to be retreated. If you do, you would usually choose a different form of treatment.
  • Some doctors believe that treatment for genital warts will help prevent the spread of HPV infections and keep genital warts from returning.

Types of treatment

Treatments for genital warts include medicines, freezing, laser, or surgery.

The type of medical treatment for genital warts will depend on:

  • The number, size, and location of warts.
  • The side effects of treatment.
  • The skill of the doctor for each treatment option.
  • The cost of treatment, which varies depending on:
    • The cost of medicine.
    • Any specialized equipment used.
    • The number of treatments needed.
  • The problems caused by the warts (such as blockage of the urethra).
  • Your preference.
  • If you are pregnant. Some wart medicines should not be used during pregnancy.

Medicines

Doctors often recommend medicine applied to warts (topical drug treatment) as the first choice of treatment. A doctor will apply the medicines that have a high risk of causing damage to the skin around the warts. You can apply others at home.

Caution: Do not use nonprescription wart removal products to treat genital warts. These products are not intended to be used in the genital area and may cause serious burning.

Surgery and other treatment

Surgery to remove genital warts may be done when:

  • Medicine treatment has failed and the removal of warts is considered necessary.
  • Warts are widespread.

What to think about

Without treatment, external genital warts may remain unchanged, increase in size or number, or go away. Studies show that no one treatment is completely successful because there is no cure for genital warts. All treatments have advantages and disadvantages. The benefits and effectiveness of each treatment need to be compared with the side effects and cost.

  • Treatment of warts usually requires a series of applications rather than a single treatment.
  • Warts in moist areas usually respond better to treatments applied to the area, such as creams or acids.
  • Warts on dry skin may respond best to freezing (cryotherapy) or surgical removal.
  • Cryotherapy may be done when genital warts are visible and bothersome and are growing in a small area. Repeat treatments may be needed to remove all wart tissue.
  • The success of surgery is related to the number of warts. The success rate is higher and additional treatments are less likely to be required when surgery is performed on fewer and smaller warts. But surgery is less likely to be needed for a few small areas of warts. Surgery may require anesthesia.
  • Small areas of warts can be quickly treated with removal methods, such as cryotherapy or surgical excision.
  • Self-applied medicines may be used for larger areas of warts that need longer or repeated treatments.

A biopsy of warts that do not go away on their own or after treatment is often done to rule out precancerous or cancerous conditions.

Several choices of treatment for pregnant women have been found to be effective and safe, including trichloroacetic acid (TCA), cryotherapy, and surgery.

Prevention

You can reduce your risk of becoming infected with the human papillomavirus (HPV) or another sexually transmitted infection (STI). You also can reduce the risk of spreading HPV to your sex partner(s).

Practice safe sex

Preventing a sexually transmitted infection (STI) is easier than treating an infection after it occurs.

  • Talk with your partner about STIs before beginning a sexual relationship. Find out whether he or she is at risk for an STI. Remember that it is possible to be infected with an STI without knowing it. Some STIs, such as HIV, may be in your blood for 3 to 6 months before they can be detected.
  • Be responsible.
    • Avoid sexual contact if you have symptoms of an STI or are being treated for an STI.
    • Avoid sexual contact with anyone who has symptoms of an STI or who may have been exposed to an STI.
  • Don't have more than one sex partner at a time. Having several sex partners increases your risk of getting an STI.

Male condom use

Condom use can reduce the risk of becoming infected with HPV. You can help prevent infection if you use them every time you have sex. Condoms must be put on before beginning any sexual contact.

Female condom use

Even if you are using another birth control method, you may wish to use condoms to reduce your risk of getting an STI. Female condoms are available for women whose partners do not have or will not use a male condom. Female condoms may lower the risk of HPV infection of the cervix. But these condoms are more effective at lowering the risk of other STIs.

Vaccines

If you are age 26 or younger, you can get the HPV shot. The vaccines Cervarix(What is a PDF document?) and Gardasil(What is a PDF document?) protect against two types of HPV that cause cervical cancer. Gardasil also protects against two types of HPV that cause genital warts. Three shots are given over 6 months. It is recommended for children age 11 or 12, but can be given as early as age 9. For girls who have not already gotten the vaccine, it is recommended up to age 26. For boys who have not already gotten the shot, the vaccine is recommended up to age 21. Gardasil is used for males. Females can get either vaccine. For more information, see the topic Immunizations.

Click here to view a Decision Point.HPV: Should My Child Get the Vaccine?

The HPV vaccine is not useful for treating women who already are infected with HPV.5 But it may protect a woman against types of the HPV virus other than the one causing her infection.

Home Treatment

Home treatments may not cure HPV and genital warts. But a doctor may prescribe medicine that you can use at home, such as podofilox lotion or gel or imiquimod cream.

Caution: Do not use nonprescription wart removal products to treat genital warts. These products are not intended for the genital area and may cause serious burning.

You can use at-home care to feel more comfortable.

  • Take sitz baths. Fill a tub with a few inches of warm water and sit in it for 10 or 15 minutes every day.
  • Squeeze warm water from a bottle over your genital area to provide comfort and cleansing.
  • Use a heat lamp or a hair dryer several times a day to dry your genital area. Make sure to hold the lamp or dryer at least 18 inches from your skin.

It is important to remember that most infections are minor, without serious complications. Some cases of HPV and genital warts disappear without treatment, although human papillomavirus (HPV) may still be present in your body's cells.

Medications

Medicine may be used to destroy bothersome genital warts, relieve your symptoms, and reduce the amount of area affected by warts, particularly when the warts are:

  • Visible, bothersome, and growing in a small area.
  • A cosmetic concern and you want them removed. Warts that are growing around the anus or on external genitals, such as on the penis or vulva, may be removed because they are unsightly. Some treatments that remove genital warts are more likely to leave scars. So cosmetic concerns about scarring may help guide the choice of treatment.

Topical medicine often is the first treatment. For safety, a doctor will apply the topical medicines that could damage the skin around the warts. You can apply other medicines at home. If warts return after one course of treatment with topical medicine, they are treated again only if there are clear reasons for retreatment.

Medicines are not used to treat abnormal cell changes found on a Pap test. For more information on treating abnormal cell changes caused by high-risk HPV, see the topic Abnormal Pap Test.

Treatment applied at home

The following medicines can be applied to the affected area (topical treatment) at home:

Imiquimod (such as Aldara)
Podofilox lotion or gel (such as Condylox)
Sinecatechins (such as Veregen)

Do not use these medicines during pregnancy.

Imiquimod and podofilox appear to be the most effective medicine options that can be applied at home. Read the instructions carefully before using these medicines.

Treatment applied by a doctor

Treatment by a doctor can:

  • Treat areas that you cannot reach easily.
  • Treat a large area.
  • Remove the warts quickly.
  • Be expensive.
  • Be painful.
  • Have side effects.

Medicines applied by a doctor include:

Treatment during pregnancy

Treatment for pregnant women includes trichloroacetic acid (TCA) and bichloroacetic acid (BCA), which have been found to be both effective and safe. Podophyllin resin, interferon, and fluorouracil should not be used during pregnancy because they can harm the fetus.

What to think about

Avoid sexual contact in the treated area until the area is completely healed.

Some medicine may be more expensive than others.

Warts on the vulva or penis that do not go away on their own or after treatment often are biopsied to rule out precancerous or cancerous conditions.

Recurrence

Removing genital warts does not cure an HPV infection. Although warts may go away with topical treatment, they may return because the HPV virus may still be in the body's cells.

Even if genital warts have been removed or destroyed:

  • You may still be able to infect sex partners with HPV.
  • You should continue to use condoms during sexual intercourse if you have multiple sex partners.

Surgery

You may have surgery to remove genital warts if they are widespread and medicine or freezing (cryotherapy) fails to remove them.

If you have a high-risk type of HPV that causes an abnormal Pap test, your doctor may recommend certain types of surgery. For more information about surgical methods to treat abnormal cell changes, see the topic Abnormal Pap Test.

Surgery choices

Surgical methods that may be used include:

Surgical treatment for pregnant women

Surgical choices for pregnant women with genital warts include electrocautery, surgical excision, loop electrosurgical excision (LEEP), and laser surgery.

What to think about

The success of surgery is related to the number of warts present. The success rate is higher and additional treatments are less likely to be required when surgery is performed on fewer and smaller warts. But surgery is less likely to be needed for a few small areas of warts.

Surgery may be more expensive than some other treatment choices.

Other Treatment

There is no other treatment for genital warts.

Other Places To Get Help

Organizations

American Academy of Dermatology
P.O. Box 4014
Schaumburg, IL  60168
Phone: 1-866-503-SKIN (1-866-503-7546) toll-free
(847) 240-1280
Fax: (847) 240-1859
Web Address: www.aad.org
 

The American Academy of Dermatology provides information about the care of skin, hair, and nails. You can locate a dermatologist in your area by using their "Find a Dermatologist" tool at www.aad.org/find-a-derm.

American Social Health Association
P.O. Box 13827
Research Triangle Park, NC  27709
Phone: 1-800-227-8922 (STI Resource Center Hotline)
(919) 361-8400
Fax: (919) 361-8425
Email: info@ashastd.org (general information)
Web Address: www.ashastd.org
 

The mission of the American Social Health Association is to improve the health of individuals, families, and communities, with a focus on preventing sexually transmitted diseases and their harmful consequences.

Centers for Disease Control and Prevention (CDC): National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention
1600 Clifton Road
Atlanta, GA  30333
Phone: 1-800-CDC-INFO (1-800-232-4636)
(404) 639-3534
TDD: 1-888-232-6348
Email: cdcinfo@cdc.gov
Web Address: www.cdc.gov/nchstp/od/nchstp.html
 

The National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention is a branch of the Centers for Disease Control and Prevention (CDC). Their Web site provides information and updates on sexually transmitted diseases (STDs), human immunodeficiency virus (HIV), and tuberculosis (TB). You can also find fact sheets on these health topics.

KidsHealth for Parents, Children, and Teens
10140 Centurion Parkway North
Jacksonville, FL  32256
Phone: (904) 697-4100
Fax: (904) 697-4220
Web Address: www.kidshealth.org
 

This website is sponsored by the Nemours Foundation. It has a wide range of information about children's health, from allergies and diseases to normal growth and development (birth to adolescence). This website offers separate areas for kids, teens, and parents, each providing age-appropriate information that the child or parent can understand. You can sign up to get weekly emails about your area of interest.

National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health
NIAID Office of Communications and Government Relations
6610 Rockledge Drive, MSC 6612
Bethesda, MD  20892-6612
Phone: 1-866-284-4107 toll-free
Phone: (301) 496-5717
Fax: (301) 402-3573
TDD: 1-800-877-8339
Web Address: www.niaid.nih.gov
 

The National Institute of Allergy and Infectious Diseases conducts research and provides consumer information on infectious and immune-system-related diseases.

References

Citations

  1. Centers for Disease Control and Prevention (2006). Genital warts. In Sexually Transmitted Diseases Treatment Guidelines, 2006. Available online: http://www.cdc.gov/STD/treatment/.
  2. Bonnez W, Reichman RC (2010). Papillomaviruses. In GL Mandell et al., eds., Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 7th ed., vol. 2, pp. 2035–2049. Philadelphia: Churchill Livingstone Elsevier.
  3. International Collaboration of Epidemiological Studies of Cervical Cancer (2007). Cervical cancer and hormonal contraceptives: Collaborative reanalysis of individual data for 16,573 women with cervical cancer and 35,509 women without cervical cancer from 24 epidemiological studies. Lancet, 370(9599): 1609–1621.
  4. U.S. Department of Health and Human Services (2007). Human Papillomavirus: HPV information for Clinicians. Available online: http://www.cdc.gov/std/hpv/hpv-clinicians-brochure.htm.
  5. Hildesheim A, et al. (2007). Effect of human papillomavirus 16/18 L1 viruslike particle vaccine among young women with preexisting infection. JAMA, 298(7): 743–753.

Other Works Consulted

  • American Academy of Pediatrics (2009). Human papillomavirus. In LK Pickering et al., eds., Red Book: 2009 Report of the Committee on Infectious Diseases, 28th ed., pp. 477–483. Elk Grove Village, IL: American Academy of Pediatrics.
  • Centers for Disease Control and Prevention (2011). Recommendations on the use of quadrivalent human papillomavirus vaccine in males: Advisory Committee on Immunization Practices (ACIP). MMWR, 60(50): 1705–1708. Also available online: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6050a3.htm?s_cid=mm6050a3_e.

Credits

By Healthwise Staff
Primary Medical Reviewer Sarah Marshall, MD - Family Medicine
Specialist Medical Reviewer Jeanne Marrazzo, MD, MPH - Infectious Disease
Last Revised March 7, 2012

Last Revised: March 7, 2012

Author: Healthwise Staff

Medical Review: Sarah Marshall, MD - Family Medicine & Jeanne Marrazzo, MD, MPH - Infectious Disease

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