The Family Papovaviridae has two genera:

1. papillomaviruses that produce warts in mucocutaneous sites;

2. polyomaviruses, the first class of DNA virus that was recognized to cause tumours in animals, including JC virus, BK virus and SV-40.

Papilloma viruses are non-enveloped DNA viruses with icosahedral symmetry, measuring 45–55 nm in diameter. The human papilloma viruses (HPV) represent a group of over 80 viruses that infect epithelial cells to produce warts in a number of sites: more than 30 types infect the genitalia. Over 90% of all HPV infections are caused by two low-risk (nontumorogenic) strains of HPV, serotypes 6 and 11. These are usually associated with the visible genital lesions and may also be associated with laryngeal and upper respiratory tract condylomata. Other lowrisk HPV serovars include 40, 42, 43, 44, 54, 61, 70, 72 and 81. High-risk serovars include HPV 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 68, 73 and 82. Overall, HPV16, 18, and to a lesser extent 31, 33, 35, 45, 53 and 58 are the most common high-risk papilloma viruses causing infections in humans. HPV 16 infection represents about 50% of those infections associated with progression to carcinoma.

Genital warts and cervical cancer

Genital human popillomavirus infections (HPV)

Since genital HPV infections are not reportable to the CDC, the real prevalence and numbers of new infections is not really known.