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There are more than 100 types of HPV (human papillomavirus), including 40 which can infect the genital tract and are sexually acquired. Genital HPV infections are frequently asymptomatic and resolve without causing disease. However, certain HPV infections can cause cervical cancer, other cancers and genital warts.
HPV types associated with cancer are called oncogenic or 'high risk' types; 13 have been recognised by the WHO International Agency for Research on Cancer. HPV types that do not cause cancer are termed 'low risk' types. Two of these 'low risk' types cause genital warts. HPV types are referred to by number (assigned in the order in which they were discovered).
HPV infections are extremely common in the sexually active population and are particularly common in the first few years after onset of sexual activity.
The HPA has developed laboratory, modelling and surveillance techniques and systems to describe and monitor the type-specific epidemiology of HPV infections and related disease, and to estimate the expected impact of HPV immunisation.
Cervical cancer is the second most common cancer in females worldwide and is the 12th most common cancer in females in the UK. HPV is a necessary, although not sufficient, cause of cervical cancer. Around 70% of cervical cancers are attributed to two types: HPV 16 and 18. At least 10 other HPV types are also associated with a high risk of cervical cancer (e.g. HPV 31, 45). High risk HPV infections are also associated with cancer of the penis, vulva, vagina, anus, mouth and oro-pharynx.