Human papillomavirus (HPV) affects epithelial cells and has a particle diameter of 55 nm. One feature is the proliferation of the skin epithelium as well as the mucous membranes. In the initial stage, the pathogen usually affects the basal cells of the epithelium, penetrating them through microtrauma. Localized papillomas usually occur in the skin of the neck, armpits, groin, and genitals (most commonly), oral mucosa, and nasopharynx.
This virus can be asymptomatic for many years. To detect HPV, electron microscopy or molecular hybridization methods are used.
Types of human papillomaviruses
In humans, HPV is distinct in that it affects the mucous membranes and skin. Among the large number of papillomaviruses, there are species with low and high oncogenic risk. Oncogenic properties have been shown 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 lead to 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 in the cervix or anus. In terms of skin, HPV 16 and 18 are the most common, as are HPV 5 and 8, which can lead to skin cancer. The best known form of HPV-induced cancer is cervical cancer. But men can also get the papilloma virus, which at worst causes cancer of the penis or anus.
Women are often faced with HPV 16 - it is a way in which parasitism is observed introsomal, that is, outside the cellular chromosome (benign). HPV 18 is characterized by a high risk of developing oncology - first, benign tumors are formed, which after a while degenerate into cancer. Virions, in this case, are tiny (up to 30 nm).
Various types of HPV infections lead to:
- cervical neoplasms;
- invasive or pre-invasive oncology;
- genital warts of the urinary tract and genitals.
Ingestion of the pathogen by the body does not always lead to illness. It all depends on predisposing factors: increased sexual activity, vitamin deficiency, pregnancy, hypothermia, endometriosis, smoking, alcohol abuse, etc. It should be noted that a viral infection can occur even in an organism with a good immune system.
Infection characteristics
Human papillomavirus is highly contagious. It is usually transmitted by direct skin-to-skin or mucous membrane-to-mucus membrane contact with an infected person. In genital infections, this most often occurs during vaginal or oral sex. Large numbers of sexual partners or other STDs (sexually transmitted infections) increase the risk. Indirect transmission through contaminated objects, clothing or sheets is also possible, but rarely occurs.
In 7% of cases, transmission of the virus from mother to child can occur during childbirth, when the infection is active. The risk increases to 40% if you are infected with HPV 16 or 18.
By penetrating the epithelium, violating integrity, 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 spreads quickly to other people. As a rule, warts and condylomas do not metastasize and usually disappear spontaneously.
HPV symptoms
The incubation period lasts up to 9 months (average of 3 months). HPV can be present in the body without obvious symptoms. The virus can go unnoticed for months or years. Even at this stage, it's contagious.
Skin warts usually occur in groups and increase with itching. The two most common forms of papilloma are grayish, hard, raised with a broken surface (common wart) or flattened and reddish (flat wart). Sharp warts are found on the soles of the feet or on the heels, grow inward, and therefore are often painful.
The causative agents of genital warts occur in warm, moist parts of the body, so they are located in the folds and mucous membranes. They can cause symptoms like itchiness or burning. The incubation period, that is, the time between infection and the onset of symptoms, in genital warts varies from 3 weeks to 8 months.
There are several forms of genital warts caused by different pathogens:
- Genital warts. Pale or reddish nodules that usually group together and occur on the lips, vagina, penis, urethra, anal canal, and rectum. They are highly contagious.
- Flat warts. They appear in the form of flattened knots and are found mainly on the female genitals. They increase your risk of developing cancer.
- Giant warts (Buschke-Levenshtein tumors). They grow in huge formations, destroying 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 may be affected, resulting in pink stalk growths. 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 wart discoloration) or a microscope.
Furthermore, the virus can also take up residence in cells without any tissue changes. There they speak of latent infection, that is, 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 integumentary tissue of the skin and mucous membrane, settle in the nuclei of cell structures and multiply there. Typically, these HPV infections go unnoticed and heal on their own without consequences, as the immune system successfully fights the pathogen.
However, some of the HPV types create changes in the skin, 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 mainly benign, but they can also degenerate and lead to cancer. For example, cancer can occur decades after HPV infection. Cancer of the external female genitals (cancer of the vulva and vagina), anal cancer, cancer of the penis, and cancer of the mouth and throat (tumours of the head and neck) are also possible.
establishing diagnosis
A test for HPV infection is performed on women as part of preventive visits to the gynecologist. During a gynecological exam, a swab is removed from the lining of the cervix, this is called a Pap smear (cytological exam). The resulting material is examined for tissue changes to determine precancerous conditions.
Alternatively, an HPV test can be done, in which cellular material from a mucosal smear or tissue sample is tested in a laboratory for certain viruses. However, this allows you to prove only the infection of the affected area, but not to make any statement about whether tissue changes have occurred. Therefore, an HPV test makes sense, especially when combined with a Pap smear, and can help detect cancer precursors at an early stage.
If the test is positive, this is still not a cause for concern, as infection does not always lead to cancer. Regular examination is recommended to detect tissue changes at an early stage. On the other hand, a negative test result does not allow us to say whether there was an infection in the past that the body has successfully fought against.
For men, there is no prophylactic test where the test is performed regularly. If there is a corresponding cancer, examination of the tumor can determine whether HPV infection is at the root of the cancer.
Specialized 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 cure human papillomavirus
In most cases, the disease does not require treatment because it disappears on its own and the viruses are no longer detected. However, if this is not the case, the infection may last longer and persist for months or years.
So far, there are no methods of systemic impact on this virus, so it would be possible to completely destroy it. However, treating the resulting warts reduces the number of viruses, so 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 repeatedly.
Therapeutic tactics depend on the type of HPV and the associated condition of the disease:
- Plantar and genital warts can be treated with topical formulations of salicylic acid.
- Cryotherapy is also a frequently used method for HPV. In this case, the wart is burned cold, using liquid nitrogen.
- Lasers or electrocautery are equally applicable methods.
As the frequency of relapses is quite high, it is advisable to have regular examinations and use a condom even several months after the lesions have disappeared, so as not to infect the sexual partner.
For HPV cancers, treatment is much more difficult. In cervical cancer, it is usually advisable to remove the uterus, the upper part of the vagina and the ovaries, respectively. This can be complemented with radiotherapy to rule out the likelihood of relapse. Other cancers caused by HPV are more often treated with targeted therapy such as radiation or chemotherapy.
It should be remembered that the operation is not a fundamental solution, but only solves an aesthetic problem, as after removal the virus is able to remain in the surrounding tissues and warts can appear again.
infection prevention
There are two vaccinations: bivalent HPV 16 and 18 and quadrivalent HPV 6, 11, 16 and 18. Vaccination is recommended for all 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 disease. The effectiveness of using condoms to prevent the transmission of infection can significantly reduce the risk of developing this condition. The most promising method for preventing and treating the early stages of disease caused by this infection is a specific multivalent vaccine.