How is high-risk HPV infection caused?

High-risk human papillomavirus (HPV) infection is caused by sexual contact with an infected individual. HPV is a DNA virus that infects the basal epithelial cells of the skin and mucous membranes—particularly those of the anogenital tract, oropharynx, and less commonly, the conjunctiva or respiratory tract. Transmission occurs primarily through direct skin-to-skin or mucosa-to-mucosa contact during vaginal, anal, or oral sex; penetrative intercourse is not required for transmission. The virus gains entry through microabrasions in the epithelium, where it establishes a persistent infection in dividing keratinocytes. Certain HPV types—including 16, 18, 31, 33, 45, 52, and 58—are classified as “high-risk” because their oncoproteins (especially E6 and E7) disrupt critical tumor-suppressor pathways (p53 and retinoblastoma protein), leading to uncontrolled cellular proliferation and increasing the risk of developing precancerous lesions and invasive carcinomas—most notably cervical, anal, vaginal, vulvar, penile, and oropharyngeal cancers. Risk factors for persistence and progression include immunosuppression (e.g., HIV infection or organ transplantation), smoking, long-term oral contraceptive use, multiparity, and co-infection with other sexually transmitted pathogens.