Human papillomavirus infection is an infection by human papillomavirus (HPV). Most HPV infections cause no symptoms and resolve spontaneously. In some people, an HPV infection persists and results in warts or precancerous lesions. The precancerous lesions increase the risk of cancer of the cervix, vulva, vagina, penis, anus, mouth, or throat. Nearly all cervical cancer is due to HPV with two types, HPV16 and HPV18, accounting for 70% of cases. Between 60% and 90% of the other cancers mentioned above are also linked to HPV. HPV6 and HPV11 are common causes of genital warts and laryngeal papillomatosis.An HPV infection is caused by human papillomavirus, a DNA virus from the papillomavirus family, of which over 170 types are known. More than 40 types are transmitted through sexual contact and infect the anus and genitals. Risk factors for persistent HPV infections include early age of first sexual intercourse, multiple partners, smoking, and poor immune function. HPV is typically spread by sustained direct skin-to-skin contact, with vaginal and anal sex being the most common methods. Occasionally, it can spread from a mother to her baby during pregnancy. It does not spread via common items like toilet seats. People can become infected with more than one type of HPV. HPV affects only humans.HPV vaccines can prevent the most common types of infection. To be most effective, they should be used before an infection occurs and are therefore recommended between the ages of nine and 13. Cervical cancer screening, such as with the Papanicolaou test (pap) or looking at the cervix after using acetic acid, can detect early cancer or abnormal cells that may develop into cancer. This allows for early treatment which results in better outcomes. Screening has reduced both the number cases and the number of deaths from cervical cancer in the developed world. Warts can be removed by freezing.HPV is the most common sexually transmitted infection globally. Most people are infected at some point in their lives. In 2012, about 528,000 new cases and 266,000 deaths occurred from cervical cancer worldwide. Around 85% of these occurred in the developing world. In the United States, about 27,000 cases of cancer due to HPV occur each year. About 1% of sexually active adults have genital warts. While cases of warts have been described since the time of ancient Greece, their viral nature was not discovered until 1907.