Human papillomavirus (HPV) attacks epithelial cells and has a particle diameter of 55 nm. One characteristic is the proliferation of the skin epithelium and the mucous membranes. In the initial stage, the pathogen usually attacks the basal cells of the epithelium and penetrates them through microtraumas. Localized papillomas usually appear on the skin of the neck, armpits, groin and genitals (most common), the lining of the mouth, and the nasopharynx.
This virus can be asymptomatic for many years. Electron microscopic or molecular hybridized methods are used to detect HPV.
Types of human papillomavirus
In humans, a distinction is made between HPV, which affects the mucous membranes and the skin. Among the multitude of papillomaviruses there are types with low and high oncogenic risk. It has been shown that oncogenic properties are linked to the ability to integrate DNA into the genome of human cells.
The virus is activated in 10-20% of cases. Depending on the type, this can lead to benign or malignant lesions. Some HPVs are not oncogenic. They lead to the appearance of warts and genital warts. The most common are HPV 6 and 11.
HPV oncogenes are at high risk of developing cancerous lesions, especially on the cervix or anus. Regarding the skin, HPV 16 and 18 are more common, as are HPV 5 and 8, which can lead to skin cancer. The most well-known form of HPV-induced cancer is cervical cancer. But men can also become infected with the papillomavirus, which in the worst case causes penile or anus cancer.
Often women face HPV 16 - this is a form in which introsomal parasitism is observed, that is, outside the cell chromosome (benign). HPV 18 is characterized by a high risk of developing oncology - benign tumors initially form, which degenerate into cancer after a while. Virions in this case are tiny (down to 30 nm).
Different types of HPV infections lead to:
- neoplasms of the cervix;
- invasive or pre-invasive oncology;
- Genital warts of the urinary tract and genitals.
The uptake of the pathogen into the body does not always lead to disease. It all depends on the predisposing factors: increased sexual activity, vitamin deficiency, pregnancy, hypothermia, endometriosis, smoking, alcohol abuse, etc. It should be noted that a viral infection can also occur in an organism with a good immune system.
Features of the infection
Human papillomaviruses are highly contagious. It is usually transmitted through direct skin-to-skin or mucous membrane-to-mucosal contact with an infected person. In genital infections, this most commonly occurs during vaginal or oral sex. Having a large number of sexual partners or other STIs (sexually transmitted infections) increases the risk. Indirect transmission through objects, contaminated clothing, or bed linen is also possible, but rarely occurs.
In 7% of cases, the virus can be transmitted from mother to child during childbirth if the infection is active. The risk increases to 40% if you are infected with HPV 16 or 18.
Penetrating the epithelium, violating its integrity, the papillomavirus infection promotes the growth of the lower layer of epithelial cells in the form of warts or warts. This form of the disease is contagious and quickly spreads to others. Warts and condylomas usually do not cause metastases and often go away spontaneously.
HPV symptoms
The incubation period is up to 9 months (3 months on average). HPV can be present in the body with no obvious symptoms. The virus can go undetected for months or years. Even at this stage, it's contagious.
Skin warts usually appear in clusters and increase with scratching. The two most common papilloma shapes are either greyish, hard, raised with a broken surface (common wart), or flat and reddish (flat wart). Barbed warts are found on the soles of the feet or on the heels, grow inward and are therefore often painful.
The pathogens of genital warts occur on moist and warm parts of the body and are therefore localized in the folds and on the mucous membranes. They can cause symptoms such as itching or burning. The incubation period, i. e. the time between infection and the appearance of symptoms, is 3 weeks to 8 months for genital warts.
There are different forms of genital warts that are caused by different pathogens:
- Genital warts. Pale or reddish nodules, often in groups, appearing on the labia, vagina, penis, urethra, anal canal, and rectum. They are highly contagious.
- Flat warts. They appear in the form of flat knots and are mainly found on the female genital organs. They increase the risk of developing cancer.
- Giant warts (Buschke-Levenshtein tumors). They grow into huge formations and destroy the surrounding tissue. In rare cases, they can degenerate and lead to squamous cell carcinoma.
Infection of the mucous membranes of the upper respiratory tract is also possible. The conjunctiva of the eyes can be affected, causing pink stem growth. It is more difficult to recognize an asymptomatic course, which the doctor can only detect with the help of aids such as acetic acid (which causes discoloration of the warts) or a microscope.
In addition, the virus can implant itself in cells without any tissue changes. Then they speak of a latent infection, i. e. the presence of pathogens but without symptoms. After infection, this phase can last from several weeks to several months.
Possible consequences
When infected, viruses penetrate the cells of the skin and mucous membrane tissue, settle in the nuclei of cell structures and multiply there. Such HPV infections usually go unnoticed and heal without any consequences, as the immune system successfully fights the pathogen.
However, some of the HPV types cause skin changes, that is, growths. Possible forms are genital warts or warts and papillomas, which can affect the face, arms or legs, for example.
The tissue changes caused are mostly benign, but can also degenerate and lead to cancer. Cancer, for example, can appear decades after an HPV infection. Cancer of the external female genital organs (vulva and vaginal cancer), anal cancer, penile cancer as well as mouth and throat cancer (tumors in the head and neck area) are possible.
to make a diagnosis
In women, a test for HPV infection is carried out at the gynecologist as part of the preventive examinations. A gynecological exam involves taking a swab from the lining of the cervix, called a Papanicolaou test (cytological exam). The resulting material is examined for tissue changes to determine precancerous conditions.
Alternatively, an HPV test can be performed, in which cell material from a mucous membrane swab or a tissue sample is tested for certain viruses in a laboratory. However, only the infection of the affected area can be detected with this, but no statements can be made as to whether the tissue changes have occurred. Therefore, an HPV test is particularly useful in combination with a Pap test and can help to identify cancer precursors at an early stage.
If the test is positive, this is not a cause for concern, as infection does not always lead to cancer. Regular examination is recommended in order to detect tissue changes at an early stage. Conversely, a negative test result does not allow a statement to be made as to whether there was an infection in the past that the body successfully fought.
In men, there is no prophylactic exam where the test would be done on a regular basis. If a corresponding cancer is present, examining the tumor can determine whether an HPV infection is the root of the cancer.
Special DNA techniques, such as real-time PCR, are also used in laboratory diagnostics. Anogenital warts caused by HPV types 6 and 11 can be easily identified during a pelvic exam.
How to cure the human papillomavirus
In most cases, the disease does not require treatment as it will go away on its own and no more viruses will be detected. However, if this is not the case, the infection can last longer and last for months or years.
To date, there are no methods with a systemic effect on this virus that could completely destroy it. Treating the resulting warts, however, reduces the number of viruses so that in many cases the immune system can fight off other viruses and thus get rid of them. In some cases, pathogens survive and can cause symptoms over and over again.
The therapeutic tactics depend on the type of HPV and the associated clinical picture:
- Plantar and genital warts can be treated with topical salicylic acid formulations.
- Cryotherapy is also a commonly used method for HPV. In this case, the wart is cold-burned with liquid nitrogen.
- Lasers or electrocautery are equally applicable procedures.
Since the frequency of relapses is quite high, it is advisable to check yourself regularly, even several months after the lesions have disappeared, and to use condoms so as not to infect your sexual partner.
Treatment for HPV cancers is much more difficult. In cervical cancer, it is often advisable to have the uterus or the upper part of the vagina and ovaries removed. This can be supplemented with radiation therapy to rule out the likelihood of relapse. Other cancers caused by HPV are most commonly treated with targeted therapy, such as radiation or chemotherapy.
It should be remembered that surgery is not a cardinal solution, it only solves a cosmetic problem, since after removal the virus can remain in the surrounding tissues and warts can reappear.
Infection prevention
There are two vaccinations: bivalent HPV 16 and 18 and quadrivalent HPV 6, 11, 16 and 18. The vaccination is recommended for all young girls aged 14 and over.
Vaccination does not protect against all types of HPV. Therefore, all women between the ages of 25 and 65, even if they are vaccinated, are advised to have regular smear tests.
Timely detection and complete removal of genital warts reduces the risk of the disease. The effectiveness of using condoms in preventing the transmission of infection can greatly reduce the risk of developing this condition. The most promising method of preventing and treating the early stages of the disease caused by this infection is a specific multivalent vaccine.