12 Facts About Human Papillomavirus

Pornpak Khunatorn, iStock via Getty Images
Pornpak Khunatorn, iStock via Getty Images / Pornpak Khunatorn, iStock via Getty Images

Human papillomavirus may have been covered in your high school health class, but there are many things that set it apart from other sexually transmitted infections. The severity of symptoms varies greatly: Warts that appear anywhere on the body are a result of HPV, as are most cervical cancer cases. Most people who get HPV never realize they have it, and with millions contracting the virus each year, chances are you’ll catch it at some point in your life. From its many types to the best way to protect yourself from it, here’s what you should know about human papillomavirus

1. Human papillomavirus infects the skin.

One distinguishing trait of human papillomavirus—and papillomaviruses affecting all animals—is that it infects the skin. When the virus causes symptoms, it provokes some inflammation or change in the skin tissue. This change can include warts, benign tumors, and tumors that become cancerous. Because it lives in the skin and mucous membranes of the body, HPV is usually transmitted through sexual contact.

2. Human papillomavirus is known for causing cervical cancer.

Most cervical cancer cases can be traced back to HPV infections. Cancer that affects the cervix—the part of the female reproductive system connecting the uterus to the vagina—is a serious global health issue. It’s the second most common cancer in women in underdeveloped countries, with 311,000 people dying from it worldwide each year. Fortunately, cervical cancer also has one of the most effective screening tests ever developed [PDF]. A Pap smear is administered by collecting cells from the surface of the cervix and analyzing them for any changes that could indicate the development of cancer. With regular Pap smears, cervical cancer is easy to catch and prevent, but they aren't always affordable to people without health insurance. This may explain why 85 percent of cervical cancer deaths happen in low- and middle-income countries.

3. There are many types of human papillomavirus.

There are more than 100 types of human papillomavirus, and only 14 of them can cause cancer. Out of that number, an even smaller group is responsible for most cervical cancer diagnoses and precancerous cervical lesions. HPV types 16 and 18 are behind 70 percent of these cases. But just because a type doesn’t cause cancer doesn’t mean it can’t be a problem. HPV types 6 and 11 have been linked to non-cancerous genital warts and respiratory papillomatosis, a condition that causes potentially life-threatening tumors to grow in the airways between the nose, mouth, and lungs.

4. High-risk HPV has no visible symptoms.

Even if a case of human papillomavirus doesn’t show clear symptoms, it can still be dangerous. Unlike the HPV types that cause genital warts, high-risk HPV types don’t present any outward signs before cervical cancer develops. That’s why receiving regular Pap smears is important—even if you feel healthy.

5. Almost everyone gets infected with human papillomavirus.

Human papillomavirus is the most common sexually transmitted infection on Earth. Fourteen percent of the U.S. population contracts it each year, and there are currently 80 million people in the country with one type of the virus.

6. Most people with HPV don’t know they have it.

Human papillomavirus may be pervasive, but it’s not regarded with the same level of severity as many other pandemic-causing viruses. That’s because most types of HPV are unrelated to cancer, and they may not even cause obvious symptoms. A huge majority—about 90 percent—of HPV infections go away on their own within two years.

7. It can take years for symptoms of human papillomavirus to appear.

Many people who contract HPV never show symptoms. In other cases, people are infected unknowingly for weeks to years before signs—such as bumps, warts, or lesions—start to emerge. This long, unpredictable period between exposure and the disease’s visibility can sometimes make it impossible to pinpoint exactly when a patient was infected.

8. Cancers caused by human papillomavirus affect men and women.

While cervical cancer is the best-known side effect of HPV infection, it’s not the only cancer caused by the disease. Human papillomavirus can cause cancerous tumors to grow on the vulva, vagina, anus, penis, and oropharynx (the area at the back of the throat). Because many people only know HPV as the virus that causes cervical cancers, the threat it poses to men is often downplayed. Its link to various cancers shows that men should get the HPV vaccine not only to protect their female sex partners, but also to protect themselves.

9. HPV-related cancer can be prevented with a vaccine.

Cervical cancer is one of the few cancers you can vaccinate yourself against, thanks to a human papillomavirus vaccine introduced in 2006. Gardasil equips the body against cervical cancer-causing HPV types 16 and 18. It’s also effective at preventing HPV types 6 and 11, the types mostly likely to cause genital warts and respiratory papillomatosis; and types 31, 33, 45, 52, and 58, which are linked to all the cancers HPV can cause. The vaccine comes in two or three shots administered over 6 months. Because it’s most effective at protecting people who are not yet sexually active, the best time for everyone to receive it is in late childhood or early adolescence.

10. The man who linked HPV to cervical cancer won the Nobel Prize.

Much of what we know about human papillomavirus today is thanks to Harald zur Hausen. In 1974, the German scientist and his colleagues discovered there were multiple types of human papillomavirus, and in 1979, he identified the HPV strain responsible for genital warts. His most influential work began in the 1980s, when he isolated HPVs 16 and 18—the two HPV types that cause most cervical cancers. In 2008, at age 72, he received the Nobel Prize in Physiology or Medicine for his work connecting cervical cancer to human papillomavirus.

11. The word papilloma means "tumor."

Papillomavirus comes from the word papilloma, a noncancerous growth on the skin, like a benign tumor or a wart. The etymology of papilloma reveals that the term was originally more specific. In Latin, papilla means "nipple," and in Greek, omameans "tumor," with the words combining to indicate "a tumor resembling a nipple." Many mammals can catch papillomaviruses, which is why the phrase human papillomavirus is used to describe pathogens that infect our species.

12. People in past centuries have come up with creative explanations for warts caused by HPV.

All skin warts are caused by human papillomavirus. Humans have been experiencing this symptom of HPV for thousands of years, with written accounts of warts dating back to ancient Greece and Rome. The condition has also inspired notable folklore throughout history. To explain the cause of warts, people have blamed killing toads, touching livestock, washing hands in water in which eggs have been boiled, and masturbating. Historical folk remedies for warts include spitting on them first thing in the morning, as well as rubbing a slug on them and impaling it on a thorn for nine nights in a row.