Human Papillomavirus (HPV) Strains 16 and 18

The Human Papillomavirus (HPV) is the most common sexually transmitted disease (STD) also referred to as sexually transmitted infection (STI). There are more than 100 types of HPV and they are categorized as low-risk and high-risk HPV. The two most common high-risk HPV strains are HPV 16 and 18 which may lead to a high risk of cervical, vaginal, vulvar, anal and penile cancers.

HPV infections are eventually cleared without treatment within 18 to 24 months and hence, doctors may recommend a watch-and-wait approach as the infected cells are shed naturally for the majority of people. However, if the persistent HPV is type 16 or 18, the affected people are at risk of developing genital, anal or oral cancer depending on the location of the infection. HPV is the most commonly diagnosed STD in the United States and many other countries. According to the Centres for Disease Control and Prevention (CDC), about 13 million Americans are infected with HPV every year.

Even though HPV is the most common STI, there are certain misconceptions about this disease. HPV may cause skin warts but they are not STDs. It is extremely important to understand the risk factors associated with HPV so that one can take the necessary precautions.

Risk Factors with HPV 16 and 18

HPV-infected people may not witness any abnormal symptoms. While HPV can affect anyone and several risk factors could be linked with HPV 16 and 18. The risk of HPV increases if you have multiple sex partners or engage in sex with someone who has had many partners. Moreover, if you are a man and engage in sex with men (MSM), you may be infected with HPV.

If you have Human Immunovirus (HIV) or another health condition which may worsen your immune system, you are at a high risk of being infected by HPV. It is universally known that HPV can be passed through vaginal and anal intercourse. However, it can also spread through oral sex.

HPV can be transmitted by intimate skin-to-skin contact, in areas that are not protected by condoms or if you engage in unprotected sex. Transgender people are equally at risk as compared to others. Research has confirmed that smoking can amplify the risk of HPV-related cervical cancer. People having HPV are also at risk of developing Chlamydia, which is a sexually transmitted bacterial infection.

Cancers and HPV

According to the CDC, HPV is responsible for about 90% of anal and cervical cancer, 70% of vaginal and vulvar cancers and 60% of penile cancers. HPV testing for cervical cancer is usually performed for women with a Pap test, also known as a Pap smear. HPV testing available for women can determine if HPV is present and if present, can determine whether the HPV is low-risk or high-risk HPV.

Cervical Cancer and HPV

Women may be prone to cervical cancer as HPV-infected cells are often shed from the cervix. Women may develop cervical cancer at a young age as the clearance rate is high and the immune systems are more active in young women.

The American College of Obstetricians and Gynaecologists (ACOG) and CDC recommend that women under 30 years should go for a Pap test every three years or can substitute it with an HPV test every five years. Pap smears are not only used to detect cervical cancer but also HPV-16 and HPV-18 strains that might later lead to cancer. ACOG also recommends that women aged 30 to 65 go for a Pap test every three years or an HPV test every five years or a Pap and HPV test together every five years.

If you test positive for HPV 16 or 18, it doesn't mean you will develop cervical cancer. But, the dysplasia found in a Pap test may increase the risk of developing cancer. Your doctor can treat dysplasia or conduct more tests to rule out the possibility of cancer. Doctors can monitor the changes to the cervix and can often tell which changes could pose danger.

HPV 16 and Throat Cancer

HPV 16 can cause cancer of the oropharynx which is commonly known as oropharyngeal cancer or throat cancer. Oral HPV infection and oropharyngeal cancer are very common among men as compared to women. According to the report published in the journal titled 'Annals of Internal Medicine' in November 2017, researchers stated that high-risk oral HPV infection is prevalent among men who indulge in the same sex or have more than two oral sex partners.

HPV Treatment

Doctors focus on curing the symptoms of the conditions caused by HPV. There are a few vaccines which may help to prevent HPV infections, but that may not do away with the need for safer sexual practices

HPV Vaccine

The HPV vaccine involves two shots which are separated by 6 to 12 months for children aged 9 to 14 years. For people aged 15 to 26 years, three shots could be given over six months. People aged 27 to 45 years can also take the HPV vaccine if they have not been previously vaccinated for HPV. The HPV bivalent vaccine (Cervarix), the HPV quadrivalent vaccine (Gardasil) and the HPV 9-valent vaccine, recombinant (Gardasil 9) may be suggested by the doctors.

The Gardasil 9 vaccine is advised by the majority of healthcare providers and may prevent the HPV strains which can cause genital warts and cervical cancer. This HPV vaccine protects against two low-risk HPV strains (6 and 11) and seven high-risk strains (16, 18, 31, 33, 45, 52, and 58). Common side effects of the Gardasil 9 vaccine are pain, swelling, redness or irritation at the injection site and a mild headache following the injection.

Some parents may feel hesitant to give HPV vaccine to their child as it is associated with sexual activity. However, considering the risk factors associated with HPV as something that causes cancer, it's advised to vaccinate children on time.

Other Treatments

Genital warts may be cured without any medication within two years. However, if they are not, the genital or anal warts can be treated with prescribed medications such as Aldara (imiquimod) cream, Condylox (podofilox) gel and Veregen (sinecatechins) cream. Furthermore, if these medications fail to cure genital warts, there are other options like cryotherapy, electrocautery, use of the trichloroacetic acid solution and laser therapy.

Generally, the precancerous cells in the cervix are treated by Loop Electrosurgical Excision Procedure (LEEP). If an HPV-infected person develops cancer, they may have to consult a doctor to treat their respective cancer.


HPV is very common and the majority of people may not experience any peculiar symptoms. HPV infections may not need treatment as they are cured within 18 to 24 months, but if you test positive for HPV, you should consult a doctor immediately.

Untreated HPV infections can often lead to cancers. Getting vaccinated can be one of the best ways to prevent HPV infections, but incorporating safe sex practices can prevent the spread of HPV and reduce the risk of developing cancer.

Updated on: 09-Feb-2023


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