What Is HPV? Symptoms, Causes, Diagnosis, Treatment, and Prevention

Joseph Bennington-Castro

The human papillomavirus — or HPV — is a group of more than 150 related viruses.

Each virus in the group has an associated number, which is known as its “HPV serotype.”

Some HPV serotypes can cause cutaneous (skin) warts, or noncancerous papillomas, which is where the name of the virus comes from.

Skin warts are generally harmless, but they are contagious — meaning they can be passed from one person to another — and they can be aesthetically distressing to some people. Warts that grow on the bottoms of the feet, called plantar warts, can also cause pain while walking.

Other types of HPV can cause genital warts, or Condyloma acuminata — soft bumps that can grow in the anal and genital areas on both men and women.

Still other types of HPV can cause dysplasia, or precancerous changes, in the cervix, vagina, vulva, anus, penis, and oropharynx — the area at the back of the throat that includes the base of the tongue and tonsils.

Virtually everyone is infected with one or more types of HPV during their lifetime, but many will never know it because they never have any symptoms or other consequences of the infection.

Types of HPV: Skin, Mucosal, High Risk, Low Risk

HPV lives in cells found on the surface of the skin and in the moist mucous membranes that line many areas of the body.

Skin Warts

About 75 percent of HPV types cause warts on the skin, such as on the arms, face, chest, hands, and feet, according to the American Cancer Society (ACS). (1)

In healthy people, the immune system can fight off the viruses that cause skin warts, but this is often not the case in people whose immune systems are compromised — by human immunodeficiency virus (HIV), for example — suppressed by drugs to prevent organ rejection or treat autoimmune diseases, or simply less effective because of older age.

In these populations, HPV infection of the skin may not be so benign.

Mucosal, or Genital, Warts

The other HPV types — more than 40, according to the Centers for Disease Control and Prevention (CDC) — are considered mucosal types, or genital types (sometimes called anogenital types) because they typically infect the anal or genital area. Mucosal HPV types can infect the following bodily areas:

Mucosal HPV types are categorized as either low risk or high risk.

Low-Risk Mucosal HPV

Low-risk HPV types can cause genital warts, which occur around the genitals and anus, as well as in the mouth and throat.

About 90 percent of genital warts are caused by HPV types 6 and 11, according to the CDC. (2) The HPV vaccine protects against both of these types of HPV.

High-Risk Mucosal HPV

High-risk HPV types can cause cancer. Scientists have identified about a dozen high-risk HPV types, although HPV types 16 and 18 are responsible for most HPV-related cancers.

What Are HPV 16 and 18?

HPV 16 and 18 are types of human papillomavirus that have been shown to significantly increase the risk of cervical cancer as well as genital cancers in men and women.

HPV 16 also causes the majority of cases of oropharyngeal cancer and has been linked to vocal cord cancer in people age 30 or younger, according to a study published in January 2019 in Annals of Otology, Rhinology, and Laryngology. (3)

The HPV vaccine protects against both HPV types 16 and 18, as well as several other cancer-causing types of the virus and the two main causes of genital warts.

Signs and Symptoms of HPV

Skin warts, which come in an array of sizes, shapes, and appearances, are generally diagnosed with a visual examination. If it’s not clear that a growth is a wart, a dermatologist may take a biopsy, or small tissue sample, to examine under a microscope.

Genital warts may also be diagnosable simply by taking a look, or a doctor may apply an acetic acid solution to the area to whiten the warts, making them more visible.

Precancerous cell changes in the cervix cause no symptoms but can be detected with the Pap test, in which a sample of cells is collected and examined under a microscope.

Early vaginal, vulvar, and cervical cancers related to HPV may cause no symptoms, but advanced-stage cancer can lead to abnormal vaginal bleeding or discharge and pain during intercourse.

Signs and symptoms of oropharyngeal cancer can include persistent sore throat, a lump in the neck, and persistent ear pain.

Vocal cord cancers typically causes hoarseness or a change in the voice.

Early penile cancer may cause changes in skin color and thickening of the skin.

Signs and symptoms of anal cancer include anal bleeding, pain, itching, or discharge; swollen lymph nodes in the anal or genital area; and changes in bowel habits and stool.

You should see your doctor if you have any signs or symptoms of HPV-related cancers.

Causes and Risk Factors of HPV

Skin warts are spread through direct skin-to-skin contact with an infected person.

You can also spread warts from one part of your body to another through touch.

Children and teens, people who bite their nails or pick at hangnails, and people with a weakened immune system have a higher risk of getting common warts.

Mucosal HPV types are transmitted through intimate skin-to-skin contact — most commonly through vaginal or anal sex but also through oral sex.

Anyone who’s sexually active is at risk for getting HPV, even if you’ve had only one sexual partner.

You’re at higher risk for genital or oral HPV if you:

Still, nearly all sexually active men and women get HPV at some point in their lives, the CDC notes, and it’s not uncommon to be infected with more than one type of HPV at a time.

Symptoms from HPV may develop years after you become infected, so it’s often impossible to know who transmitted the virus to you.

Even with no symptoms, you can pass HPV on to other people, and you can get HPV from someone who doesn’t show any symptoms.

How Is HPV Diagnosed?

Skin warts and genital warts can usually be diagnosed on sight during a physical examination, but your doctor may also refer you to a dermatologist for a biopsy to be sure your skin condition is a wart.

If you’re a woman with detectable genital warts, your doctor may also perform a colposcopy — a procedure that uses a light and a low-power microscope — to find genital warts on your cervix that are too small to see with the naked eye.

All women can be screened for HPV infection of the cervix with the HPV test, which is done by gently removing some cervical cells with a swab and testing them for the presence of HPV. The test can detect HPV types 16 and 18 and provide broad results for 12 other high-risk (cancer-causing) HPV types in cervical tissue.

Women who have a positive HPV test should seek advice from a doctor on how best to follow up to prevent cervical cancer. Generally, a positive HPV test will be followed up with a colposcopy if HPV types 16 or 18 are found, or repeat testing in 12 months if types of HPV other than 16 or 18 are found, notes Lab Tests Online. (4)

Cancers in areas other than the cervix are diagnosed by taking a biopsy of abnormal-appearing areas and examining the tissue under a microscope. However, scientists are looking for ways to detect the cancers — or precancerous changes — earlier. And in some areas, they’re making progress.

In a study published in June 2019 in Annals of Oncology, researchers found that antibodies to the human papillomavirus type 16, which causes a majority of HPV-associated oropharyngeal cancers in the United States, develop in the body between 6 to 40 years prior to a clinical diagnosis of throat cancer, and their presence indicates a strong increased risk of the disease. (5)

They also found that having HPV 16 antibodies increased the risk of throat cancer far more in white people than in Black people: nearly 100-fold in white people, but 17-fold in Black people.

The researchers cautioned, however, that identifying people at high risk is only the first step in screening for oropharyngeal cancer and that the subsequent steps that would lead to timely treatment have yet to be determined.

Duration and Prognosis of HPV

In many cases, the immune system fights off HPV, so a person never develops symptoms and tests negative on an HPV test, if such a test is available for the body part that came into contact with the virus.

In other cases, the immune system does not prevent the virus from infecting the cells, but the infection doesn’t immediately cause symptoms. In fact, it may never cause symptoms, but the virus can be transmitted to another person through skin-to-skin or sexual contact.

And in still other cases, an HPV infection causes abnormal changes in the infected cells that can eventually develop into cancer. The time between an infection and the development of precancerous changes or cancer may be years or even decades.

The earlier HPV-related symptoms are found, the more likely they can be treated successfully.

Treatment and Medication Options for HPV

How HPV is treated depends on how it is affecting you.

If you have a skin wart, you may choose to leave it alone until it goes away on its own, treat it with an over-the-counter product, or see your doctor for treatment.

For genital warts, your doctor can prescribe several topical medicines to apply to external warts at home, or you may be treated in the doctor’s office with topical medication, cryotherapy (freezing the warts), or surgical removal.

Topical medication may need to be applied repeatedly for weeks or even months to fully treat genital warts. Cryotherapy may also need to be repeated multiple times.

Similar medical and surgical therapies may be used for warts located on the cervix or in the vagina, anus, or urethra (the tube through which urine exits the body). Laser treatment is another option for some internal warts, notes American Family Physician. (6)

Abnormal cells in the cervix may be removed surgically or using other techniques.

And cancers caused by HPV are treated with standard cancer therapies, including chemotherapy, radiation therapy, and surgery.

Prevention of HPV

The first HPV vaccine came on the market in 2006, and within six years of its introduction, infections with HPV types 6, 11, 16, and 18 had decreased by 64 percent among teen girls ages 14 to 19, and by 34 percent among women ages 20 to 24, according to an article published in February 2016 in the journal Pediatrics. (7)

HPV types 6 and 11 cause 90 percent of genital warts, and types 16 and 18 cause most cases of HPV-related cancer.

A subsequent systematic review and meta-analysis published in June 2019 in The Lancet confirmed the impact of HPV vaccination. (8) The meta-analysis included data on 60 million people from 14 different countries that had set up HPV vaccine programs in the previous 10 years.

It showed that HPV infections dropped by 83 percent among girls ages 13 to 19 and 66 percent among women aged 20 to 24. For genital warts, the drop was 67 percent among teen girls ages 15 to 19, 54 percent for women ages 20 to 24, and 31 percent for those ages 25 to 29. Precancerous cervical lesions also dropped, by 51 percent among teens ages 15 to 19 and 31 percent among women ages 20 to 24.

The study also showed that genital warts among males dropped 48 percent for those ages 15 to 19 and 32 percent for those ages 20 to 24. The researchers attributed the lower rates among teen boys and men to herd protection provided by the vaccination of young women.

At least two studies have also found that HPV vaccination lower rates of oropharyngeal HPV infections. One, published in January 2018 in the Journal of Clinical Oncology, studied young adults ages 18 to 33 in the United States from 2011 to 2014. (9) A second, published in June 2020 in The Journal of Infectious Diseases, studied men who have sex with men and transgender women age 18 to 26 in three U.S. cities during 2016 to 2018. (10)

The HPV vaccine currently used in the United States, Gardasil 9, protects against HPV types 6, 11, 16, and 18, as well as against five other types that can cause cancer: 31, 33, 45, 52, and 58.

Australian researchers have found that the HPV vaccine not only protects against genital warts and cancer, but also against childhood recurrent respiratory papillomatosis (RRP), an uncommon but incurable disease in which the virus causes wart-like growths to develop in the respiratory tract, eventually making it difficult to breathe. RRP is caused by HPV types 6 and 11, noted a study published in November 2017 in The Journal of Infectious Diseases. (11)

RRP that occurs in childhood is believed to be passed from mother to child around the time of birth. RRP can also occur in adults, usually in early adulthood, around the time HPV is commonly acquired through sexual transmission.

In the United States, the HPV vaccine is approved for preteens and adults through age 45. The CDC recommends that all adolescents get two doses of vaccine at age 11 or 12. (12)

For most people who get a first dose before their 15th birthday, only one more dose is needed, 6 to 12 months later. People who get their first dose on or after their 15th birthday need three doses total, with the second dose given one to two months after the first, and the third dose given six months after the first.

In spite of the proven protections offered by the HPV vaccine, not all Americans who could enjoy those benefits are getting them. Data released by the CDC on August 23, 2019, showed that during 2017 through 2018, coverage with one or more doses of HPV vaccine among teens ages 13 to 17 rose from about 66 percent to just over 68 percent, and the percentage of teens who had received all recommended doses of the HPV vaccine increased from about 49 percent to just over 51 percent, with the increases observed only among males. (13)

In contrast, in Australia in 2017, just over 80 percent of 15-year-old girls, and nearly 76 percent of 15-year-old boys had received three doses of the HPV vaccine, according to Cancer Australia. (14)

Complications of HPV

The most serious potential complication of HPV infection is cancer. The link between genital infection with certain strains of HPV and cervical cancer was established in the early1980s by German virologist Harold zur Hausen and his colleagues — work that eventually led to a successful HPV vaccine. (15)

Since then, other researchers have established causative links between HPV and many other cancers, including cancers of the vagina, vulva, anus, penis, oropharynx, and vocal cords.

And scientists continue to explore the possible role of HPV in still other cancers, including prostate cancer and nonmelanoma skin cancers.

Cervical Cancer

Before the Pap test was widely adopted in the late 1950s, cervical cancer was the leading cause of cancer death for women in the United States.

But although cervical cancer is now almost entirely preventable, the American Cancer Society estimates that in 2020 about 13,800 new cases of invasive cervical cancer will be diagnosed, and about 4,290 women will die from cervical cancer. (16)

Most invasive cervical cancers are found in women who have not had regular Pap tests.

Today the HPV test can be done to detect HPV in the cervix, alerting women and their doctors that further testing or follow-up may be necessary to detect precancerous lesions in the cervix.

Oral Cancer

The CDC estimates that about 15,500 cases of HPV-associated oropharyngeal cancer are diagnosed in men in the United States each year — compared with about 3,500 cases in women. (17) Oropharyngeal cancer is cancer that develops on the back and sides of the throat, tonsils, and base of the tongue.

In years past, oropharyngeal cancer was seen primarily in individuals with heavy tobacco and alcohol use — and those are still risk factors for oral and oropharyngeal cancers. But according to the American Cancer Society, the rate of new cases of HPV-negative oral cavity and oropharyngeal cancer is dropping, while the rate of HPV-positive oropharyngeal cancer is on the rise among both men and women. (18)

Recent research suggests the incidence of vocal cord cancer (glottic carcinoma) is following a similar pattern. In the past, it was mainly seen in older adults who were heavy smokers. But a study published in January 2019 in Annals of Otology, Rhinology, and Laryngology found that since 2004, the incidence has been increasing in younger people (age 30 or younger) with no smoking history who test positive for HPV. (3)

It’s believed that people get oral HPV during oral sex, although why men develop HPV-associated throat cancer so much more often than women is not known.

What is known is that more widespread use of the HPV vaccine could lower the rate of high-risk HPV infection in men and women and consequently lower the rate of HPV-related cancer, including oropharyngeal cancers, in both sexes. A study first reported at the 2017 Annual Society of Clinical Oncology (ASCO) meeting found that the prevalence of oral infection with four HPV types, including two cancer-causing types, was 88 percent lower in young adults who reported receiving at least one dose of an HPV vaccine. (19)

Prostate Cancer

HPV likely has a causal role in prostate cancer. That was the conclusion of a systematic review published in July 2020, in the journal Infectious Agents and Cancer. (20)

The researchers cited numerous findings to support their conclusion but said the most important one is the reasonably consistent evidence that high-risk HPV types are significantly more prevalent in prostate cancers than in normal prostate tissues and benign prostate tissues (referring to benign prostatic hyperplasia, or an enlarged prostate). The researchers additionally noted that the mechanism by which HPV leads to cancer in the prostate is not known, but it is different from that seen in cervical cancer.

Skin Cancer

Researchers have found evidence that HPV in the skin may raise the risk of nonmelanoma forms of skin cancer when the skin is exposed to ultraviolet (UV) light. This link has long been suspected, and it was demonstrated recently by German researchers, in a study published in November 2017 in the journal PLoS Pathogens, in mouse models of HPV. (21)

Lead investigator Frank Rösl, of the German Cancer Research Center in Heidelberg, said in a press release, “These findings are an important argument in favor of also developing vaccines against cutaneous papillomaviruses.”

Building on the HPV-skin cancer connection, in a study published in February 2019 in the European Journal of Clinical Microbiology and Infectious Diseases, researchers examined cancerous and noncancerous skin biopsies. They discovered HPV in 43 percent of the nonmelanoma skin cancer specimens, and almost no HPV in the noncancerous specimens. (22)

The study doesn’t prove that HPV causes skin cancer; further research is needed to fully understand the connection.

Research and Statistics: Who Has HPV?

As stated earlier, nearly all sexually active men and women get HPV at some point in their lives, but in most cases the infection does not persist. In addition, the only widely available HPV test is for women, to test the tissue of cervix. So for most people, the first sign of an HPV infection is the appearance of genital warts, or the appearance of signs and symptoms of some form of HPV-related cancer, the most serious consequence of HPV infection.

According to a study published in August 2019 in the CDC’s Morbidity and Mortality Weekly Report (MMWR), an average of 34,800 cancers reported annually in the United States from 2012 to 2016 were attributable to HPV. (23) Of these, 92 percent were attributable to HPV types targeted by the HPV vaccine. The most common cancers reported during this period were cervical (9,700) and oropharyngeal cancers (12,600).

The incidence of cervical cancer has dropped by one-half since the mid-1970s, says the American Cancer Society, while incidence rates of cancer of the oral cavity and pharynx decreased by 1 to 2 percent per year among Black men and women from 2007 to 2016, but increased annually by about 1 percent among non-Hispanic white men and women. (24)

The incidence of anal squamous cell carcinoma (SCAA) — a type of anal cancer that can be caused by HPV — is on the rise in the United States, according to research published in November 2019 in the Journal of the National Cancer Institute. The researchers found that the incidence of this type of anal cancer increased by 2.7 percent per year from 2001 to 2015, particularly among people age 50 and older. Anal cancer mortality rates increased 3.1 percent per year from 2001 to 2016, with statistically significant increases in people age 50 and older.

However, certain younger people also saw their risks rise. Compared with adults born around 1946, Black men born in approximately 1986 had a nearly fivefold higher risk of SCCA, while the risk doubled among white men and white women born after 1960, per an article published in November 2019 in the Journal of the National Cancer Institute. (25)

The prevention and treatment of HPV infections and HPV-associated cancers is the subject of hundreds if not thousands of ongoing studies in the United States and around the world.

BIPOC Communities and HPV

HPV can infect anyone, but different populations, including Black, Indigenous, and People of Color (BIPOC) communities, have been found to have different rates of infection in various areas of the body, as well as different rates of HPV-related cancer.

Such variability may reflect differences in prevailing community behavior, biology, or unequal access to screening tests and medical care.

The CDC reports estimates of HPV infections by race and ethnicity, based on data from the National Health and Nutrition Examination Survey (NHANES), a cross-sectional survey designed to monitor the health and nutritional status of the civilian noninstitutionalized U.S. population. (26)

The most recent estimates were published in April 2017 and reflect rates from the years 2011 to 2014 for genital HPV and the years 2013 and 2014 for oral HPV among adults ages 18 to 69. Among the findings of NHANES:

Using data from cancer registries, the CDC has also reported on rates of HPV-associated cancer among Americans of different races and ethnicities for the years 2012 to 2016. Among the findings: (27)

Related Conditions

HPV is one of several common sexually transmitted infections, or STIs, also called sexually transmitted diseases (STDs). Others include chlamydia, gonorrhea, syphilis, herpes, and HIV/AIDS.

Unlike HPV, which is a virus, chlamydia, gonorrhea, and syphilis are caused by bacteria. All three can currently be cured by antibiotics, although some strains of the bacteria that cause gonorrhea have become resistant to most antibiotics.

Herpes and HIV/AIDS are caused by viruses and cannot be cured, although they can be treated, both to reduce symptoms in the person who is infected and to reduce the likelihood of transmission of the virus to others.

Resources We Love

If you need to know more about HPV, these organizational websites can help:

Get the lowdown on skin warts — their symptoms, treatment, and prevention — from the experts on skin and skin care.

Learn the basics on sexually transmitted forms of HPV, including common myths and facts and information on the connection between HPV and cervical cancer.

The CDC offers information for parents on having their children vaccinated against HPV, as well as HPV fact sheets written specifically for men and for young women.

Check out Cleveland Clinic’s Health Library for information on oropharyngeal cancer caused by HPV.

Plantar warts — those that occur on the bottom of the feet —can make walking painful. The Mayo Clinic explains how to identify them and how they can be treated.

This government website links out to patient resources on warts, images, listings of ongoing research, and journal articles.

The National Cancer Institute provides a thorough discussion of the HPV vaccine, which protects against seven types of human papillomavirus that can cause cancer, as well as two that cause most genital warts.

This program of the American Sexual Health Association focuses on cervical cancer information and prevention and offers an online support platform for those dealing with cervical cancer.

Get the information you need on genital warts, including what they are, how you get them, and what effect, if any, they could have on a pregnancy.

For information on sexually transmitted types of HPV and for help getting tested, Planned Parenthood is the place to turn. Call 800-230-PLAN (7526).

A website for teens, by teens, Sex, Etc. offers frank talk on sexually transmitted infections, including HPV, as well as on relationships and communicating about sex with parents and peers.

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