Human papillomavirus (HPV) affects epithelial cells and has a particle diameter of 55 nm. A feature is the proliferation of the skin epithelium, as well as the mucous membranes. At the initial stage, the pathogen usually affects the basal cells of the epithelium and penetrates them through microtrauma. Localized papillomas usually occur on the skin of the neck, armpits, groin and genitals (most commonly), the mucous membrane of the mouth, and the nasopharynx.
This virus can be asymptomatic for years. Electron microscopic or molecular hybridized methods are used to detect HPV.
Types of human papillomavirus
In humans, HPV is distinguished, which affects the mucous membranes and skin. Among the large number of papillomaviruses, there are strains with low and high oncogenic risk. Oncogenic properties have proven to be associated with 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 cause the appearance of warts and genital warts. The most common are HPV 6 and 11.
HPV oncogenes are those at high risk of developing cancerous lesions, especially on the cervix or anus. In terms of skin, HPV 16 and 18 are more common, while HPV 5 and 8 can cause skin cancer. The best-known form of HPV-induced cancer is cervical cancer. But men can also get the papillomavirus, which in the worst cases causes cancer of the penis or anus.
Often women are faced with HPV 16 - this is a form in which intrasomal parasitism, that is, outside the cell chromosome (benign), is observed. HPV 18 is characterized by a high risk of developing oncology - first of all, benign tumors are formed, which after a while turn into cancer. In this case, the virions are small (up to 30 nm).
Various types of HPV infections lead to:
- neoplasms of the cervix;
- invasive or preinvasive oncology;
- genital warts of the urinary tract and genitals.
Ingestion of the pathogen does not always lead to disease. It all depends on predisposing factors: increased sexual activity, vitamin deficiency, pregnancy, hypothermia, endometriosis, smoking, alcohol abuse, etc. It should be remembered that a viral infection can occur even in an organism with a good immune system.
Features of the infection
The human papillomavirus is highly contagious. It is transmitted from skin to skin or from mucous membrane to mucous membrane, usually by direct contact with an infected person. In genital infections, this most often occurs during vaginal or oral sex. Multiple sex partners or other STIs (sexually transmitted infections) increase the risk. Indirect transmission through objects, contaminated clothing or bedding is also possible, but rarely occurs.
In 7% of cases, mother-to-child transmission of the virus may occur during childbirth when the infection is active. The risk increases to 40% if you are infected with HPV 16 or 18.
Penetrating the epithelium, disrupting its integrity, papillomavirus infection promotes the growth of sub-epithelial cells in the form of warts or warts. This form of the disease is contagious and spreads quickly to others. As a rule, warts and condylomas do not metastasize and often disappear on their own.
HPV symptoms
The incubation period lasts up to 9 months (average 3 months). HPV can be found in the body without obvious symptoms. The virus may go undetected for months or years. It is contagious even at this stage.
Skin warts usually form in clusters and increase with scratching. The two most common forms of papilloma are either raised (common wart) or flat and reddish (flat wart) with a grayish, hard, broken surface. Prickly warts are found on the soles of the feet or heels, grow inward and are therefore often painful.
The causative agents of genital warts occur on moist and warm parts of the body, therefore they are localized in folds and mucous membranes. They can cause symptoms such as itching or burning. The incubation period of genital warts, that is, the time between infection and the onset of symptoms, varies between 3 weeks and 8 months.
There are several types of genital warts caused by different pathogens:
- Genital warts. Pale or reddish nodules that usually appear in clusters and form on the labia, vagina, penis, urethra, anal canal, and rectum. They are extremely contagious.
- Flat warts. They appear as straight knots and are found mainly on the female genitals. They increase the risk of developing cancer.
- Giant warts (Buschke-Levenshtein tumors). They grow into gigantic formations, destroying the surrounding tissues. In rare cases, they can degenerate and lead to squamous cell carcinoma.
Infection of the mucous membrane of the upper respiratory tract is also possible. The conjunctiva of the eyes may be affected, causing pink body enlargement. It is more difficult to detect an asymptomatic course, which the doctor can only see with the help of aids such as acetic acid (which causes the discoloration of the warts) or a microscope.
In addition, the virus can settle in cells without any tissue changes. Then they talk about a latent infection, that is, the presence of pathogens, but without symptoms. After infection, this stage can last from a few weeks to several months.
Possible consequences
When infected, viruses penetrate the cells of the integumentary tissue of the skin and mucous membranes, settle in the nuclei of cell structures and multiply there. Usually, such HPV infections go unnoticed and heal on their own without consequences, as the immune system successfully fights the pathogen.
However, some types of HPV cause skin changes, ie growths. Possible forms include genital warts or warts and papillomas, which can affect, for example, the face, arms or legs.
The tissue changes caused are mostly benign, but can also degenerate and lead to cancer. For example, cancer can occur decades after HPV infection. Cancer of the external female genital organs (cancer of the vulva and vagina), anal cancer, cancer of the penis, and cancer of the mouth and throat (tumors of the head and neck) are also possible.
diagnose
As part of preventive visits to the gynecologist, women are tested for HPV infection. During the gynecological examination, a swab is taken from the lining of the cervix, this is called the Papanicolaou test (cytological examination). The resulting material is examined for tissue changes to identify precancerous conditions.
Alternatively, an HPV test can be done, in which cell material from a mucosal swab or tissue sample is tested for certain viruses in a laboratory. However, this only allows to prove infection of the affected area, but does not make any statement about whether tissue changes have occurred. Therefore, an HPV test makes sense, especially when combined with a Pap test, and can help detect cancer precursors at an early stage.
If the test is positive, this is not yet a cause for concern, as the infection does not always lead to cancer. Regular examination is recommended to detect tissue changes at an early stage. Conversely, a negative test result does not allow us to argue whether there was an infection that the body had successfully fought in the past.
For men, there is no prophylactic examination for which the test will be carried out regularly. If a corresponding cancer is present, examination of the tumor can determine whether HPV infection is at the root of the cancer.
Special DNA techniques are also used in laboratory diagnostics such as real-time PCR. Anogenital warts caused by HPV types 6 and 11 are easily detected during a pelvic exam.
How to treat human papillomavirus
In most cases, the disease does not require treatment as it goes away on its own, and then the viruses are no longer detected. However, if this is not the case, the infection may last longer and persist for months or years.
To date, there are no methods of systemic action on this virus, by which it would be possible to completely destroy it. However, treating warts that appear reduces the number of viruses, so in most cases the immune system is able to fight off other viruses and thus get rid of them. In some cases, pathogens survive and can cause symptoms repeatedly.
Therapeutic tactics depend on the type of HPV and the associated picture of the disease:
- Plantar and genital warts can be treated with topical salicylic acid formulations.
- Cryotherapy is also a frequently used method for HPV. In this case, the wart is burned with cold using liquid nitrogen.
- Lasers or electrocautery are equally viable methods.
Since the recurrence rate is quite high, it is recommended to regularly check yourself and use condoms even a few months after the lesions have disappeared so as not to infect the sexual partner.
Treatment for HPV cancers is much more difficult. In cervical cancer, it is usually recommended to remove the uterus, the upper part of the vagina and the ovaries, respectively. This may be supplemented with radiation therapy to exclude the possibility of recurrence. Other cancers caused by HPV are most often treated with targeted therapy such as radiation or chemotherapy.
It should be noted that surgery is not a cardinal solution, it only solves a cosmetic problem, because after removal, the virus may remain in the surrounding tissues and warts may reappear.
Prevention of infection
There are two vaccines: bivalent HPV 16 and 18 and quadruple HPV 6, 11, 16 and 18. Vaccination is recommended for all teenage girls 14 years of age and older.
The vaccine does not protect against all types of HPV. For this reason, it is recommended that all women between the ages of 25-65 have regular smear examinations, even if they are vaccinated.
Timely detection and complete removal of genital warts reduces the risk of disease. The effectiveness of using condoms to prevent transmission of infection can significantly reduce the risk of developing this condition. The most promising method for the prevention and treatment of the initial stages of the disease caused by this infection is a specific multivalent vaccine.