HPV is thought to be the most common sexually transmitted infection in the world. Most people are infected with HPV at some time in their lives. There are over 100 types of HPV. Some HPV types infect the genital area and may cause warts, i.e. "low-risk" (LR) HPV, type 6 & 11. Other HPV types may cause abnormal cell changes in women of the cervix, anus, vulva(ano- genital area) or throat (oropharyngeal),or in men, the penis, anus, or throat. These are "high-risk" (HR) HPV often type 16 & 18 and can lead to cancer. Most HPV infections are transient and go away before they cause any health problems.
The types of HPV found in the anogenital and throat area are passed on during sexual contact (sexually transmitted) and may cause visible genital warts (see HPV and genital warts). In contrast most HR HPV infections are subclinical i.e. without clinical signs or symptoms, and often infect areas that are not easily visible such as the cervix, throat or anus.
Genital HPV is usually acquired by direct skin-to-skin contact during intimate sexual contact with someone who is infected. Most people are not aware that they have the virus. Increasing numbers of partners increases the risk of getting HPV, but the virus is so common it may be acquired after having only a single lifetime partner. It is usually impossible to determine when or from whom HPV was caught.