HPV Infection: How Dangerous is the Human Papillomavirus?

There are more than 100 types of the human papillomavirus or HPV. All these different types of HPV are given a number. Most types are absolutely not dangerous, but a few types are. How do you get infected, what are the symptoms and what if you have an HPV infection?

Also read: Human papillomavirus (HPV): why should you get vaccinated?

Different types of HPV

The human papillomaviruses are divided into three groups:

1. The viruses that cause infections of the skin and can cause warts (HPV1 for example causes warts on the sole of the foot).
2. The viruses that cause infections of the mucous membranes, especially in the area of ​​the genitals (the genital area), and can cause genital warts (condylomata accuminata) (for example types 6 and 11).
3. The viruses that can cause infections of the mucous membranes in the genital area and can cause various types of cancer (including types 16, 18, 31, 33, 45).

Also read: Video: HPV: what is it?

Infection

Condoms reduce the chance of infection by about 70 percent, but do not completely protect you from an HPV infection. This is because the virus is in and around the vagina, and on and around the penis. During sex, the virus can also end up in other places, such as on the hands and in the mouth.

Also read: Does frequent sex increase the risk of cervical cancer?

HPV vaccine

As a young person, you can get vaccinated against HPV for free. The vaccination works best if you get it before you come into contact with HPV. A full vaccination consists of two injections in the upper arm during one school year for the recommended age group (12 years).

HPV infection

The virus is highly contagious. It is estimated that more than 80 percent of all young women and men who have had sexual contact have been infected with (one or more types of) HPV at some point.

• In women, the risk of infection is highest in the age category before 25-30 years. Thereafter, it gradually decreases, with a second less significant prevalence peak after the age of 60 years.
• In men, unlike in women, the risk of infection does not decrease with age, but remains constant throughout the life course.

• In men and women with HIV, the chance of HPV infection is much higher than in the general population. The types most frequently found in HIV-positive people are also different from those in the general population.

Symptoms of HPV infection

Most HPV infections are asymptomatic. In addition, the body's immune system almost always clears the virus itself. This is called clearance of the virus. This usually occurs within 2 years. If this does not succeed, then there is a long-term or persistent infection. Then there is an increased risk of certain cancers and/or genital warts. It is estimated that approximately 1 percent of all HPV infections would eventually lead to cancer and/or anogenital warts.

It is not yet entirely clear why the virus is sometimes not 'cleared'. We do know that you have a greater chance of remaining infected for a long time if you smoke. But also if you use certain medications, for example against an HIV infection or after an organ transplant.

HPV and cancer

Of all cancers worldwide, the total burden of HPV-associated tumors in men and women is estimated to be approximately 5 percent.

Nearly 100 percent of all cervical cancers are caused by HPV. HPV infections are also linked to cancers of the vagina, vulva (the external part of the female genital tract), anus, penis, and some mouth and throat cancers.

Cervical cancer

• If the virus is not cleared and the HPV infection persists, abnormalities in the lining (epithelium) of the cervix may develop. These abnormalities are called cervical intraepithelial neoplasia grade 1 (CIN1). In CIN1, spontaneous clearance usually occurs (60% of cases) and only 1% eventually progresses to cancer.
• CIN1 can develop into more severe epithelial abnormalities in the form of dysplasia extending over two-thirds or the entire thickness of the epithelium (CIN2 and CIN3, respectively). In CIN3 (formerly called carcinoma in situ or CIS), genetic instability of the host cells occurs, which can cause them to degenerate into tumor cells.
• In CIN2 and CIN3 the number of lesions that disappear spontaneously is much lower (30-40%) and untreated more than 12 percent develop into cancer. CIN3 has a higher chance of developing into invasive cervical cancer.

Also read: Human papillomavirus (HPV) and cervical cancer

Anogenital cancers

In other forms of anogenital cancer, the presence of HPV 16 and HPV 18 in particular can be detected. For example, HPV types were found in 88 percent of cases of anal cancer, 70 percent of cases of vaginal cancer, 50 percent of cases of penile cancer and in 43 percent of cases of vulvar cancer.

In 2020, 247 new diagnoses of vulvar cancer were registered in Belgium. Vaginal cancers are less frequent with 44 diagnoses. That year, 187 cases of VIN3 (Vulvar intraepithelial neoplasia, grade III) and 36 cases of VAIN3 (vaginal intraepithelial neoplasia, grade III) were also registered.

As for anal and penile cancer, 213 cases of anal cancer and 97 cases of penile cancer were diagnosed.

Mouth and throat cancer

HPV has also been detected in cancers of the head and neck region (oropharyngeal cancer). HPV types (primarily HPV 16 and to a lesser extent 18) are found in approximately 50 percent of cases of oral cavity, esophageal (pharyngeal) and laryngeal (voice box) cancers.

In Belgium, there are approximately 2,500 new cases of head and neck cancer each year. The number of cases of oropharyngeal cancer is increasing in both men and women.

Also read: Can you get throat cancer from oral sex?

HPV and genital warts

Some HPV types also cause anogenital warts (condylomata acuminata) and benign mucosal lesions. Types HPV 6, HPV 11 and HPV 16 together are responsible for more than 90 percent of genital warts.

HPV 6 and 11 do not cause cervical cancer, but in rare cases they can lead to cancer of the larynx and certain types of tumors of the anus, vulva and penis.

Both types also account for nearly 100 percent of cases of recurrent respiratory papillomatosis (RRP). This is a very serious but rare condition characterized by recurrent warts or papillomas in the upper respiratory tract, primarily in the larynx.

In patients with HIV, condyloma lesions are more common than in the general population and the number of recurrences after treatment is also significantly higher.

Also read: All about genital warts

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