What is HPV (Human Papillomavirus), What Are Its Symptoms, and Why is the HPV Vaccine Important?

Cervical cancer is the second most common type of cancer in women, after breast cancer, and causes the deaths of approximately 250,000 women each year. This highly serious cancer is almost entirely caused by the Human Papillomavirus (HPV) viruses. The HPV virus, which belongs to the Papillomaviridae family, infects human epithelial cells to survive and uses the epithelial cell mechanism to multiply. This virus, directly related to cervical cancer, can also lead to many other life-threatening diseases. Therefore, in order to fight cervical cancer globally and maintain personal health, it is important to properly recognize HPV, understand its modes of transmission, and be aware of prevention methods.

What is HPV (Human Papillomavirus)?

HPV is a type of DNA virus with approximately 200 different types, which can only reside in human epithelial cells and replicate within them. This virus, with a diameter of 50-55 nanometers and containing a pair of double-stranded circular DNA genes, settles in the epithelial tissues shortly after coming into contact with the human body and causes lesions in the form of warts called "condyloma acuminatum." HPV, which commonly affects epithelial cells in the genital area, is the most common sexually transmitted infection worldwide. Studies suggest that approximately 630 million people worldwide are infected with this virus.

Human Papillomavirus, which belongs to a very large family, causes different health issues in individuals depending on the type. These types are classified into two categories: low-risk (non-oncogenic viruses) and high-risk (oncogenic viruses). Most genital warts are caused by the HPV types 6 and 11. These low-risk viruses do not lead to cervical cancer but may cause occasional genital tissue infections. HPV types 16, 18, 31, 33, 35, 45, 52, and 58 are defined as high-risk viruses and can affect not only the genital area but also the uterine mucosa, increasing the risk of cervical cancer. These high-risk virus types may remain asymptomatic for many years without causing visible warts or similar lesions in the external genital organs. This delay in recognizing cervical cancer is significant, making regular gynecological examinations and timely vaccination planning extremely important for preventing cervical cancer.

HPV, which is among the most common sexually transmitted infections and has a highly contagious nature, can lead to serious health problems, ranging from cancer to fertility loss. However, currently, there is no proven treatment option for HPV infection. To manage the severe diseases that may emerge after transmission, it is essential to correctly identify the virus and recognize the early symptoms of the disease.

How is HPV Transmitted?

HPV can settle not only in the woman's cervix and vaginal tissue epithelium but also in the epithelial cells of genital organs such as the penis, scrotum, vulva, and even the anus and bladder, leading to growth lesions in these areas. In order for the virus to replicate through DNA replication, it must reach the deepest epidermal layer, which is the epithelial cell layer. Various injuries and irritation due to sexual intercourse cause the virus to pass through the upper layers of the skin and reach the epithelial cell layer. Afterward, the proteins α6ß4 integrin in the cells and the L1 capsid protein on the HPV surface interact, allowing the virus to settle in a group of cells called keratinocytes. Since HPV is not a cytolytic virus, it only infects the cells it enters and does not cause a systemic viral infection in the body.

Shortly after the virus enters keratinocytes, they undergo terminal differentiation, leading to the formation of new viruses. The terminally differentiated keratinocyte cells eventually shed from the outermost layer of the epithelial tissue, and the virus spreads in the surrounding area through this natural desquamation process.

Human Papillomavirus is primarily transmitted through sexual contact, although perinatal transmission is also possible.

Transmission through Sexual Contact

HPV is mainly transmitted from person to person through vaginal and anal intercourse, but it can also be spread through oral sex. In addition, transmission can occur without intercourse, simply through sexual contact. Every sexually active adult individual will be infected with HPV at some point in their life, and they often remain unaware of the infection, as it usually has no symptoms, and may unknowingly transmit the virus to their partner. For a woman who has only one sexual partner, the risk of becoming infected with HPV after three years is about 46%. The viruses that cause genital warts are more contagious compared to other HPV types. A person who has been treated for genital warts caused by HPV may still transmit the virus to others, even if no warts are visible on the skin. Therefore, it is extremely difficult to determine exactly how or when HPV was transmitted during sexual activity. For this reason, a partner's HPV diagnosis should not be regarded as a sign of infidelity.

Transmission via Perinatal Transition

HPV can be transmitted from mother to baby during childbirth, and if the baby is infected, laryngeal and conjunctival papillomas are likely to develop. Additionally, a fetus developing from an egg fertilized by an HPV-infected sperm may also be at risk of being HPV-positive. Furthermore, infected genital secretions from the mother can infect the baby in the womb via the placenta.

What Are the Symptoms of HPV?

In individuals with a fully functioning immune system, many types of HPV viruses do not cause any health problems and are cleared from the body within about 1-2 years due to the immune system’s intervention. However, some viral subtypes can lead to genital warts, known as condyloma acuminatum, precancerous skin lesions, and cancers in tissues such as the cervix, penis, anus, oropharynx, vulva, and vagina. The skin lesions caused by the virus can have four different appearances: acuminatum, papular, planar, and flat.

The symptoms of HPV in active individuals vary depending on the state of the immune system. For example, in HIV-positive individuals or patients with suppressed immune systems for any reason, genital warts grow much faster than usual and may even reach large sizes. This can lead to the transformation of benign lesions into malignant tumors.

Cervical cancer resulting from high-risk HPV infection does not cause any symptoms in its early stages. However, in the clinical stages of the disease, painless vaginal bleeding and vaginal discharge resembling clear fluid are often observed. Abnormal vaginal bleeding and discharge caused by infection can be signs of many other genital diseases, so a detailed examination by a physician is necessary.

Why is the HPV Vaccine Important?

Cervical cancer is the second most common cancer in women after breast cancer. The HPV vaccine specifically increases the number of protective cells called neutralizing antibodies in mucosal secretions, preventing the virus from entering these mucosal tissues. By providing immunological protection and developing long-lasting immunity, the HPV vaccine has made cervical cancer the only cancer that can be prevented through vaccination. In addition to cervical cancer, the HPV vaccine also protects against many other serious health problems associated with the virus, including prostate cancer, Buschke-Lowenstein tumor, bladder cancer, and male infertility.