Human papillomavirus (HPV) is a very common virus that infects skin and mucous membranes. There are over 100 types of HPV, with around 40 types that specifically infect the genital area. HPV is primarily transmitted through sexual contact. Most people become infected with HPV shortly after becoming sexually active for the first time. While some types of genital HPV can cause warts, many HPV infections do not result in any symptoms at all. However, some HPV strains are linked to precancerous changes and cancer.
What is HPV?
HPV stands for human papillomavirus. It is an extremely common sexually transmitted infection, with over 200 different viral strains identified so far. Different types of HPV infect different areas of the body:
- Genital HPV infects the genital area and is spread mainly through sexual contact.
- Oral HPV infects the mouth and throat and is spread through oral sex.
- Cutaneous HPV infects the skin and is responsible for common warts on the hands and feet.
Around 40 types of HPV specifically infect the genital region. Genital HPV strains are categorized as either low-risk or high-risk:
- Low-risk HPV types, such as HPV types 6 and 11, can cause benign genital warts.
- High-risk HPV types, like HPV 16 and 18, are linked to precancerous changes and several types of cancer.
Many people mistakenly assume all types of HPV cause visible genital warts. In reality, the low-risk HPV strains 6 and 11 are responsible for around 90% of all genital warts cases. The high-risk cancer-causing strains very rarely cause warts.
HPV Transmission and Prevalence
HPV is extremely common and easily transmitted through skin-to-skin contact. It can be spread through vaginal, anal, and oral sex. HPV infections are so prevalent that nearly all sexually active adults will catch at least one type of HPV at some point.
The CDC estimates around 79 million Americans are currently infected with HPV, while about 14 million new HPV infections occur every year. Most sexually active people are exposed to the virus shortly after becoming sexually active for the first time. Proper condom use can lower, but not eliminate, the risk of HPV transmission.
Since HPV is so common and most strains do not cause any symptoms, many people can be infected for months or even years without realizing it. The vast majority of HPV infections go away on their own within 1-2 years. However, sometimes HPV lingers in the body and leads to serious health problems.
Low-Risk HPV Types That Cause Warts
There are just two HPV strains responsible for the majority of all genital wart cases:
- HPV 6 – Causes around 90% of genital warts cases.
- HPV 11 – Causes around 10% of genital warts cases.
Together, HPV 6 and 11 cause around 90% of all genital warts. However, they very rarely lead to cancer.
Genital warts appear as small, flesh-colored bumps in the genital area. They are sometimes described as having a cauliflower-like appearance. Warts may appear within weeks or months of infection. But sometimes they lay dormant for years before causing symptoms.
Around 1% of sexually active adults in the U.S. have visible genital warts at any given time. But many more are infected with HPV 6 or 11 without showing symptoms.
While troubling, genital warts are not harmful in the long run. They can be removed through topical medications or minor surgery. However, even after treatment warts may recur. There is no cure for HPV itself – even after genital warts are gone, the virus may linger in the body.
Fortunately, HPV 6 and 11 infections usually clear on their own within a couple years. Getting the HPV vaccine can also protect against the strains most linked to genital warts.
High-Risk Cancer-Causing HPV Types
Around 15 strains of HPV are classified as “high-risk” because they can lead to cell abnormalities and cancer over time:
- HPV 16 and 18: Cause around 70% of cervical cancers and can also lead to other cancers.
- HPV 31, 33, 45, 52, 58: Linked to another 20% of cervical cancers.
- HPV 35, 39, 51, 56, 59: Also high-risk strains linked to cancers.
Together, HPV 16 and 18 account for the vast majority of HPV-related cancers. HPV 16 alone is responsible for over 50% of cervical cancer cases.
Unlike the wart-causing strains, high-risk HPV types generally do not cause any visible warts or symptoms. Most people infected with high-risk HPV will not develop cancer either. HPV becomes a problem when it lingers in the body for many years and eventually causes cellular changes that may become cancerous.
Precancerous changes often have no symptoms. But if left untreated, they can progress to invasive cervical, vulvar, penile, anal, and throat cancers. HPV testing and Pap tests can detect precancerous changes, allowing early treatment before cancer develops.
There are vaccines available that can protect against HPV 16 and 18, reducing cancer risk. But screening remains crucial, since the vaccines do not cover all high-risk HPV types.
Low-Risk vs High-Risk HPV Summary
| Low-Risk HPV (Types 6, 11) | High-Risk HPV (Types 16, 18, etc) |
|---|---|
| Causes 90% of genital warts cases | Accounts for 70% of cervical cancer cases |
| Sometimes causes visible warts in genital area | Rarely causes any visible warts or symptoms |
| Usually clears from body on its own | May linger for years and lead to cancer |
| Treatable through topical creams or surgery | Pre-cancer treated through excision; cancers require chemo/radiation |
While low-risk HPV types 6 and 11 are responsible for most genital warts, the cancer-causing high-risk HPV strains do not commonly cause warts. Getting vaccinated and undergoing regular HPV screening are crucial to preventing HPV-related cancers.
Who Gets Genital Warts vs HPV Cancers?
Genital warts and HPV-related cancers affect different demographics:
Genital warts
- Most common in teens/young adults who have recently become sexually active.
- Rare after age 30 – immune system clears infection.
- Equally common among both women and men.
HPV cancers
- Rare before age 30 – cancer takes years to develop.
- Most common cervical cancer cases occur between ages 35-44.
- Cervical cancer mainly affects women; other HPV cancers like anal cancer affect both genders.
Genital warts primarily impact young, sexually active individuals whose immune systems have not yet cleared the virus. HPV cancers tend to arise later in life after years of HPV persistence. This explains why cancer-causing HPV strains do not commonly cause warts – they take so long to trigger cancer that the immune system clears the infection before warts appear.
Can HPV Be Prevented?
There are a few ways to lower your risk of acquiring HPV:
- Get vaccinated. The HPV vaccine protects against cancer-causing types 16 and 18. It also covers the wart-causing strains HPV 6 and 11. The vaccine is recommended for pre-teens ages 9-12, but can be given through age 26.
- Use condoms. Using latex condoms during sex offers some protection against HPV, though not 100%. Areas not covered by the condom can still become infected.
- Limit sexual partners. Having multiple partners increases HPV exposure. But even one partner is enough to contract HPV.
Even with precautions, HPV is extremely easy to catch. Luckily, most HPV infections clear quickly and never lead to cancer. Maintaining regular Pap tests and HPV screening can catch any abnormalities early on. Stopping smoking is also important, as it lowers the risk of HPV progressing to cancer.
There is no cure for HPV itself. However, practicing safe sex, not smoking, and undergoing regular screening provides the best protection against HPV complications.
Conclusion
HPV is a widespread virus with over 200 different strains that infect skin and mucous membranes. Low-risk HPV types 6 and 11 cause around 90% of genital wart cases, but do not lead to cancer. High-risk HPV strains like 16 and 18 rarely cause warts, but persist in the body and cause cellular changes over many years that may become cancerous.
While visible genital warts are primarily caused by low-risk HPV 6 and 11, the cancer-causing types do not usually cause any visible warts or symptoms. This is because warts appear shortly after infection when the immune system can still suppress the virus, while cancers take many years to develop.
Though catching HPV is extremely common, practicing safe sex, avoiding smoking, and getting screened regularly can greatly reduce your risk of complications from high-risk HPV strains. Vaccination is key to preventing infection from the major cancer-causing types 16 and 18 altogether.
