PAPILLOMAVIRUS

also spelled papilloma virus, also called human papilloma virus any of a group of viruses belonging to the family Papovaviridae that cause warts (papillomas) and other benign tumours in humans. They are small polygonal viruses containing circular double-stranded DNA, and more than 50 distinct types are now known on the basis of analysis of their DNA. Different types of papillomaviruses are responsible for different types of lesions: common warts (of the hands) and plantar warts (of the feet) are caused by types 1, 2, and 4, flat warts are caused by types 3 and 10, and laryngeal warts by type 11. Genital and venereal warts (condylomata acuminata) are caused by other types. Most papillomas, whether found on the skin or in the mucuous membranes of the genital, anal, or oral cavities, are benign and may actually go unnoticed for years. A minority of genital and venereal warts, however, are visible, painful, or itchy. The papillomaviruses that cause these warts are passed from one person to another by sexual intercourse, and it is estimated that about 10 percent of the adult population in developed countries has papilloma infections of the genital tract. Other types of papillomaviruses have been linked with various precancerous lesions and malignant tumours, especially cervical cancers. In fact, the presence of these viruses has been found in as many as 80 percent of women diagnosed with cervical cancer. Their presence can be detected through an ordinary pap smear.