HPV is transmitted via skin-to-skin contact and enters the body through a break in the tissue or outer layer of the skin. Genital warts are transmitted through sexual contact and are the most common sexually transmitted infection (STI). HPV 16 is associated with carcinoma of the vulva, vagina, cervix, anus, and penis. Risk factors include having multiple sexual contacts at a young age and an impaired immune system. It is estimated that approximately 50% of sexually active adults acquire HPV at some point in their lives.

Complications of HPV infection include scarring with wart removal and conversion to cancerous cells in the presence of coexisting factors. Seventy percent of cervical cancers are associated with HPV. Large genital warts may cause urinary obstruction during pregnancy; warts in the vagina can decrease elasticity of the vaginal wall and cause obstruction during childbirth.

Signs and symptoms of HPV vary according to which virus is present. Many patients are asymptomatic. Common warts appear as skin-colored papules and nodules and are usually found on the feet and hands. Plantar warts are solitary painful lesions that have a small, black center (thrombosed capillaries). Genital warts develop on moist areas: in males, on the subpreputial sac, within the urethral meatus and, less commonly, on the penile shaft; in females, on the vulva and on vaginal and cervical walls. In both genders, papillomas spread to the perineum and the perianal area. These painless warts start as tiny red or pink swellings that grow (sometimes up to 10 cm) and become pedunculated. Typically, multiple swellings give them a cauliflower-like appearance. If infected, the warts become malodorous. EV typically arises as premalignant lesions on the forehead and other sun-exposed areas and may appear as polymorphic, wartlike, red to brownish plaques. (See Genital warts.)