|
Human papillomavirus (HPV) is a DNA virus from the papillomavirus family that is capable of infecting humans. Like all papillomaviruses, HPVs establish productive infections only in keratinocytes of the skin or mucous membranes. Most HPV infections are subclinical and will cause no physical symptoms; however, in some people subclinical infections will become clinical and may cause benign papillomas (such as warts () or squamous cell papilloma), premalignant lesions that will drive to cancers of the cervix, vulva, vagina, penis, oropharynx and anus.〔 〕 In particular, HPV16 and HPV18 are known to cause around 70% of cervical cancer cases. Researchers have identified over 170 types of HPV, more than 40 of which are typically transmitted through sexual contact and infect the anogenital region (anus and genitals).〔Division of STD Prevention (1999). Prevention of genital HPV infection and sequelae: report of an external consultants' meeting. Atlanta, GA: Centers for Disease Control and Prevention〕 HPV types 6 and 11 are the etiological cause of genital warts.〔 Persistent infection with "high-risk" HPV types—different from the ones that cause skin warts—may progress to precancerous lesions and invasive cancer. High-risk HPV infection is a cause of nearly all cases of cervical cancer. However, most infections do not cause disease. New vaccines have been developed to protect against certain types of HPV infection (see HPV vaccines). 70% of clinical HPV infections in healthy young adults may regress to subclinical in one year and 90% in two years. However, when the subclinical infection persists—in 5% to 10% of infected women—there is high risk of developing precancerous lesions of the vulva and cervix which can progress to invasive cancer. Progression from subclinical to clinical infection may take years, providing opportunities for detection and treatment of pre-cancerous lesions. In more developed countries, cervical screening using a Papanicolaou (Pap) test or liquid-based cytology is used to detect abnormal cells that may develop into cancer. If abnormal cells are found, women are encouraged to have a colposcopy. During a colposcopic inspection, biopsies can be taken and abnormal areas can be removed with a simple procedure, typically with a cauterizing loop or, more commonly in the developing world—by freezing (cryotherapy). Treating abnormal cells in this way can prevent them from developing into cervical cancer. Pap smears have significantly reduced the incidence and fatalities of cervical cancer in the developed world. It was estimated in 2012 that there were 528,000 cases of cervical cancer world-wide, and 266,000 deaths. It is estimated that there will be 12,900 diagnosed cases of cervical cancer and 4,100 deaths in the U.S. in 2015.〔 There are about 48,000 cases of genital warts in UK men each year.〔(【引用サイトリンク】title=BBC News - Gay men 'should get anti-cancer jab' )〕 HPV causes cancers of the throat, anus and penis as well as causing genital warts.〔Open AIDS J. 2014 Sep 30;8:25-30. doi: 10.2174/1874613601408010025. eCollection 2014. Prevalence of Anogenital Warts in Men with HIV/AIDS and Associated Factors. de Camargo CC1, Tasca KI1, Mendes MB1, Miot HA2, de Souza Ldo R1〕 ==Signs and symptoms== Over 170 HPV types have been identified and are referred to by number.〔.〕〔 Types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 68, 73, and 82 are carcinogenic〔.〕 "high-risk" sexually transmitted HPVs and may lead to the development of cervical intraepithelial neoplasia (CIN), vulvar intraepithelial neoplasia (VIN), penile intraepithelial neoplasia (PIN), and/or anal intraepithelial neoplasia (AIN). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Human papillomavirus」の詳細全文を読む スポンサード リンク
|