Human papillomavirus (HPV): What is it?
The human papillomavirus (HPV) is a virus that can infect the human reproductive system of men and women.
HPV infection is a sexually transmitted disease (STD) that is highly contagious, common in both women and men. Clinical studies show that the probability of contracting the infection over the course of a lifetime is about 80% in women and 90% in men.
Worldwide, cervical cancer is the fourth most frequent cancer in women. Almost all cases of cervical cancer are attributed to infections with human papillomavirus (HPV).
Other subtypes cause less common forms of cancer that affect the vagina, penis, anus and some areas of the head and neck (such as the throat, tongue and tonsils). Finally, other types of HPV in both men and women can cause genital warts; on the other hand, the formation of papillomas in the throat is rarer.
How is HPV infection transmitted?
HPV infection is one of the most common sexually transmitted diseases and is mainly transmitted through sexual intercourse.
The infection occurs through physical contact, in particular during vaginal, oral or anal sexual intercourse. Condom use may reduce the risk of infection, but it does not completely protect against infection.
People with a compromised immune system are more at risk of infection.
The infection can remain dormant and then re-emerge with symptoms years later.
Human papillomavirus (HPV) subtypes
Over 200 subtypes of HPV have been identified, distinguished as high and low risk.
The subtypes of low-risk HPV (LR-HPV) are:
- HPV 6, 11, 40, 42, 43, 44, 54, 61, and 70: responsible for cutaneous, oral and anogenital warts and condyloma acuminata.
The subtypes of high-risk HPV (HR-HPV) are:
- HPV 16, 18, 26, 31, 33, 35, 39, 45, 51, 52, 53, 56, 58, 59, 66, 68, 69, 73, 82.
Subtypes 16 and 18 are responsible for most cervical, vulvar, vaginal, anal, oropharyngeal and penile cancers.
Human papillomavirus in women
HPV type 16 is responsible for 50% of cases and, together with type 18, determines 70% of this pathology. Other studies show that HPV is the cause of 90% of anal cancers, 65% of vaginal cancers, 50% of vulvar cancers and 45–90% of oropharyngeal cancers.
Human papillomavirus in humans
HPV studies in women have been largely conducted through clinical screening and research programmes. Men, so far excluded from such initiatives, have recently attracted more attention in HPV research. In recent years, particular attention has been paid to the study of HPV in men and research has clearly shown the significant role of men in the transmission of the human papillomavirus (HPV).
What are the symptoms of human papillomavirus (HPV)?
Most HPV infections cause clinically mild symptoms, such as:
- warts,
- condylomata,
- papillomas.
Most HPV infections spontaneously regress due to the elimination of the virus by the immune system; only a small percentage evolve into a cancerous form.
Infection caused by high-risk subtypes is associated more with invasive carcinomas.
Vaccination against human papillomavirus (HPV)
Vaccination is a fundamental tool to reduce the risk of developing cancer associated with HPV infection. Through vaccines, effective against the viral strains responsible for most cases of cancer, it is possible to prevent infections. In Italy, anti-HPV vaccines are recommended from the age of 11 for both males and females: in fact, vaccination of both sexes limits viral circulation. Vaccination is free and effective in preventing pre-cancerous lesions. The administration takes place intramuscularly and consists of two boosters for those who are vaccinated before the age of 15, and three for those who are vaccinated afterwards.
Clinical studies have shown that vaccines are able to prevent more than 90% of HPV-associated cancers. As well as being effective, these vaccines are safe and well tolerated.
Even after vaccination, however, it is important to have regular screening checks for cervical cancer starting at age 25. In fact, the HPV vaccine is only able to protect against certain strains but not against rare strains. Furthermore, vaccination protection may not be effective against strains with which the body has already come into contact.
Pap smear test and HPV test for the diagnosis of cervical cancer
The tests used today for cervical cancer screening are the Pap Smear Test and the HPV DNA Test (test for human papillomavirus).
Diagnosis of HPV infection is based on the identification of viral nucleic acids by molecular biology techniques.
Molecular tests respond to the diagnostic needs of sensitivity and specificity, and are based on the amplification of specific targets, enabling the detection and identification of different viral subtypes.
Our molecular analysis laboratory detects 19 high-risk HPV subtypes (16, 18, 26, 31, 33, 35, 39, 45, 51, 52, 53, 56, 58, 59, 66, 68, 69, 73, 82) and 9 low-risk HPV subtypes (6, 11, 40, 42, 43, 44, 54, 61, 70).
If the HPV test is positive for one of the high-risk subtypes and microscopic analysis shows the presence of cells with altered morphological characteristics, the cervical cancer screening protocol requires a colposcopy procedure.
Colposcopy allows the presence of pre-cancerous or cancerous lesions to be confirmed and their extent to be evaluated. Colposcopy may be followed by a biopsy to characterise the type of lesion.
