Human Papillomavirus: Classification and Causes

Human papillomavirus (HPV) is a disease of oncogenic nature, which manifested as formations on the human skin or in the genital area. Men and women are equally susceptible to infection. About 60% of the world's population are potential carriers of papillomavirus infection. In most cases, the virus is transmitted from a sick person to a healthy human.

Content:

1. HPV causes.
2. Disease classification.
3. HPV symptoms.
4. References.

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HPV is a huge group of viruses, which includes 27 species and about 500 strains (types). Most of them don't entail pathologies or complications in the human organism. They remain unnoticed. However, some species are potentially dangerous. Such strains can cause various diseases, including oncology, reproductive disorders. Long-term HPV at women provokes the development oncology of the cervix.  The virus can also cause cancer of the head, lung, neck, lesions of mucosal.
The peculiarity of each pathogen is a unique structure of DNA. After infection of the human skin, the virus quickly infects the basal layer of the epithelium. Various damage of the mucous membrane or skin - microcracks, scratches, abrasions, wounds can speed up the process of infection. The HPV symptoms don’t emerge immediately, and virus can live in the body for a long time.

HPV causes.

What does human papillomavirus cause? The causative agent is a virus that infects upper layer of the skin and mucous membranes of the genital organs. Transmission of these viruses is possible only from person to person. Infection occurs through contact with the skin of a sick human. It's important to remember, that the visible manifestations of the disease may be absent for a long time.
The main causes of HPV infection:
  • Sexual contact. According to the World Health Organization, papillomavirus is one of the most common sexually transmitted diseases, more than 60% of cases.
  • Birth of a child. Infection can be transmitted at birth from mother to newborn.
  • Autoinoculation. Self-infection can occur when person breaks basic hygiene rules.
  • Household way. Human papillomavirus has a high survivability, and can be retained in a warm, humid environment of public places such as toilets, baths, gyms, and swimming pools. Infection occurs through various skin lesions directly upon contact, using personal hygiene items.

Disease classification.

Experts identify about 500 strains of human papillomavirus, which differ by set and sequence of proteins, located on their shell. Scientists divide their by 27 kinds.
Doctors denote all studied types of HPV with the help of corresponding numbers:
  • HPV types 1, 2, 3 and 4 cause plantar warts, which look like calluses;
  • HPV types 10, 49 and 28 cause the development of flat warts;
  • HPV 11, 13, 6, 16, 18, 31, 33, 35 provoke genital warts and papillomas;
  • HPV 58, 52, 39, 30, 40, 43, 42, 55, 59, 57, 62, 61, 67 - 70 provoke dangerous skin lesions, which can turn into cancer.
According to the probability of developing cancer, all human papillomaviruses are divided into several types:
  • Safe: HPV 1 - 3, 5. These types of viruses are perfectly safe in terms of cancer development.
  • Low oncogenic risk: HPV 6, 11, 42 - 44. These types of viruses can provoke cell mutations in some cases.
  • High oncogenic risk: HPV 16, 18, 31, 33, 35, 45, 68, 56, 58, 39, 70. There is evidence that these viruses can provoke malignant cell mutations and cause cervical cancer.
Types 16 and 18 cause cancer most often. Two-thirds of cancer patients have one of these HPV types.
HPV can cause cells to divide more than usual. Fast cell growth can cause warts to develop, but often it doesn’t cause any symptoms at all. The types of HPV that cause warts are not the same types that cause cancer. In persistent ‘high-risk’ HPV infections, the virus can damage DNA and cause cells to start dividing and growing out of control. This can lead to cancer. [1]

HPV symptoms.

Each type of human papillomavirus has own characteristics and specific signs. Following disorders are the most characteristic symptoms of disease:
  • Vulgar papillomas or warts. Similar formations can occur on any part of epidermis. The color of formations is almost the same as the natural skin color of the patient. Warts often appear and disappear without any reason. The degree of their manifestation depends on the changes of immune system.
  • Genital warts. Such formations can appear on the mucous membrane and skin of the genitals at women and men. A separate group of HPV, characterized by low oncogenicity, causes the occurrence of these formations. Warts can occur entire foci of infection or alone.
  • Flat warts occur on the cervix at women. The appearance of such formations is an indicator of long-term HPV. The disease causes certain changes in the epithelial cells of cervix. Infection becomes the reason of development malignant cervical tumor in 65% of cases.
  • Bovenoid papulosis. This is a precancerous condition develops most often in men. The disease is characterized by appearance on the skin of a different number spots and plaques pink, red-brown or yellow color. The surface of such plaques can be smooth or warty. They are painful when touched.
  • Bowen's disease. It's a cancer of the skin and mucous membranes, developing from cells of surface layer. It looks like a bright red skin defect with irregular contours, covered with scales and warts.
Papillomavirus can exist for a long time in the human body without manifestations. The incubation period can last from 15 days to several years. Weakening of immune system can trigger the manifestation any clinical symptoms of infection.
HPV in women is manifested in the form of condylomas - small pointed or flat bodily formations on the inner side of the vagina, external genital lips. Single or multiple warts can appear on different parts of the body: limbs, head, and neck. They are mostly painless, small and delivering psychological, aesthetic discomfort.
Papillomas in men appear on the soles of feet, hands, face and head. Papulosis of penis and testicles is possible if man is infected by dangerous HPV type. The disease is manifested by yellow or pink papillomas, which are slightly exaggerated above the skin. Another unpleasant symptom of HPV in men is Bowen's disease.
According to the CDC, the warts associated with most HPV infections go away on their own without any signs or symptoms. But the virus is still in an infected person’s body. As a result, that person may unknowingly pass HPV to sexual partners. Cancers caused by HPV often don’t show symptoms until the cancer is in later stages of growth. Regular screenings can help diagnose HPV-related health problems earlier. This can improve outlook and increase chances of survival. [2]

References.

The author used various sources of information for writing the article. The most relevant of them listed below:

  1. Cancer research UK
  2. Healthline