Human papillomavirus, or HPV, is transmitted through skin contact, states the Centers for Disease Control and Prevention. Sexually transmitted strains are specifically spread during intimate contact with genitals, including oral sex. HPV is a classification of more than 150 viruses, and roughly 40 types cause genital infections. HPV symptoms are often delayed for years or never develop, making it difficult to determine when the infection originated.
HPV infects at least 50 percent of all sexually active people, and the risk of contracting the virus increases if a person has multiple partners or became active at an early age, according to WebMD. Depending on the HPV type, the virus mainly grows in surface skins cells, known as epithelial cells, or on the moist mucous membranes of the genitals, anus, cervix, mouth and throat. Condoms do not guarantee protection from HPV because the virus may infect areas of the skin that aren’t covered. Since the virus is widespread and largely undetected, monogamy doesn’t prevent infection if either partner is an unknown carrier.
HPV types are identified as high- or low-risk strains, based on their potential to cause serious health problems, states WebMD. Low-risk strains account for approximately 90 percent of genital warts, which usually appear as cauliflower-shaped bumps within weeks or months of the initial infection. High-risk strains, such as HPV 16 and HPV 18, have an increased chance of mutating cervical cells, leading to cancer.