HPV VIRUS

 The Papillomavirus article covers the general biological features of human and animal papillomaviruses.

Human papillomavirus (HPV) is a 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. While the majority of the nearly 200 known types of HPV cause no symptoms in most people, some types can cause warts (verrucae), while others can – in a minority of cases – lead to cancers of the cervix, vulva, vagina, and anus (in women) or cancers of the anus and penis^[1] (in men). It can also cause cancers of the head and neck (tongue, tonsils and throat).^[1] Recently, HPV has been linked with an increased risk of cardiovascular disease.^[2]

More than 30 to 40 types of HPV are typically transmitted through sexual contact and infect the anogenital region. Some sexually transmitted HPV types may cause genital warts. Persistent infection with "high-risk" HPV types — different from the ones that cause skin warts — may progress to precancerouslesions and invasive cancer.^[3] HPV infection is a cause of nearly all cases of cervical cancer.^[4] However, most infections with these types do not cause disease.

Most HPV infections in young females are temporary and have little long-term significance. Seventy percent of infections are gone in 1 year and ninety percent in 2 years.^[5] However, when the infection persists — in 5% to 10% of infected women — there is high risk of developing precancerous lesions of the cervix, which can progress to invasive cervical cancer. This process usually takes 10–15 years, providing many opportunities for detection and treatment of the pre-cancerous lesion. Progression to invasive cancer can be almost always prevented when standard prevention strategies are applied, but the lesions still cause considerable burden necessitating preventive surgeries, which do in many cases involve loss of fertility.

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 invited 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 reduced the incidence and fatalities of cervical cancer in the developed world, but even so there were 11,000 cases and 3,900 deaths in the U.S. in 2008. Cervical cancer has substantial mortality in resource-poor areas; worldwide, there are an estimated 490,000 cases and 270,000 deaths each year.^[6][7]

HPV vaccines (Cervarix and Gardasil), which prevent infection with the HPV types (16 and 18) that cause 70% of cervical cancer, may lead to further decreases

Oral infection

A review of scientific studies in healthy subjects has found carcinogenic HPV in 3.5% of the studies subjects and HPV16 in 1.3%.^[65] Men have higher prevalence of oral HPV than women.^[9]

Oral HPV infection is associated with HPV-positive oropharyngeal cancer. Odds of oral HPV infection increases with the number of recent oral sex partners or open-mouthed kissing partners.^[66]Nonsexual oral infection through salivary or cross transmission is also plausible

Throat cancer

In recent years, the United States has experienced an increase in the number of cases of throat cancer caused by the human papillomavirus (HPV) Type 16. Throat cancers associated with HPV have been estimated to have increased from 0.8 cases per 100,000 people in 1988 to 2.6 per 100,000 in 2004.^[88] Researchers explain this recent data by an increase in oral sex. Moreover, findings indicate this type of cancer is much more prevalent in men than in women, something that needs to be further explored.^[89] Currently, two immunizations, Gardasil and Cervarix, are recommended to girls to prevent HPV related cervical cancer but not as a precaution against HPV related throat cancer.

Treatment

There is currently no specific treatment for HPV infection.^[1][72][79] However, the viral infection, more often than not, clears by itself.^[80] According to the Centers for Disease Control and Prevention, the body’s immune system clears HPV naturally within two years for 90% of cases.^[1] However, experts do not agree on whether the virus is completely eliminated or reduced to undetectable levels, and it is difficult to know when it is contagious.^[