HPV

HPV
Synonyms	Human papillomavirus infection
Caption	Transmission electron micrograph of HPV virions.
Field	Infectious disease, gynecology, dermatology
Symptoms	None, warts, cancer
Complications	Cervical cancer, anal cancer, oropharyngeal cancer, others
Duration	Months to years
Causes	Human papillomavirus spread by direct contact
Risks	Sexual contact, many partners, early age, smoking, immunosuppression
Diagnosis	Pap test, HPV test, tissue biopsy
Prevention	HPV vaccines, condoms, not having sex
Treatment	Cryotherapy, surgical removal, topical medications
Medication	Imiquimod, podophyllin
Prognosis	Usually good; cancer risk with persistent infection
Frequency	Most common sexually transmitted infection globally

HPV. Human papillomavirus is a group of more than 200 related DNA viruses, making it the most prevalent sexually transmitted infection worldwide. Certain high-risk types are the primary cause of several significant cancers, including nearly all cases of cervical cancer, while low-risk types primarily cause benign skin and mucous membrane growths. The discovery of the viral etiology of cervical cancer by Harald zur Hausen was pivotal, leading to his receipt of the Nobel Prize in Physiology or Medicine in 2008 and the subsequent development of preventive HPV vaccines.

Overview

The International Agency for Research on Cancer classifies several high-risk types as Group 1 carcinogens. Persistent infection with these types can lead to cellular changes, or dysplasia, which may progress to malignancies in areas like the cervix, vulva, vagina, penis, anus, and oropharynx. The World Health Organization estimates that HPV is responsible for approximately 5% of all cancers globally, with a particularly high burden in regions with limited access to screening and vaccination programs. The virus's lifecycle is tightly linked to the differentiation of epithelial cells in the skin and mucosa.

Types and classification

HPV types are numerically designated based on genetic sequence differences in the L1 capsid gene. Over 40 types typically infect the anogenital region. High-risk, or oncogenic, types include HPV16 and HPV18, which are responsible for about 70% of cervical cancers worldwide, as well as types 31, 33, 45, 52, and 58. Low-risk types, such as HPV6 and HPV11, are predominantly associated with anogenital warts and a benign condition known as recurrent respiratory papillomatosis. The International Committee on Taxonomy of Viruses oversees the formal classification of these papillomaviridae.

Transmission and risk factors

Transmission occurs primarily through intimate skin-to-skin contact, most commonly during vaginal, anal, or oral sex. The Centers for Disease Control and Prevention notes it can also spread through non-penetrative sexual activity. Key risk factors include a high number of sexual partners, early age of first sexual intercourse, co-infection with other agents like HIV or Chlamydia trachomatis, immunosuppression (e.g., post-organ transplant or with HIV/AIDS), and tobacco smoking. The virus can also be transmitted perinatally from mother to infant during childbirth.

Symptoms and health effects

Most infections are asymptomatic and cleared by the immune system within two years. When symptoms occur, they are type-specific. Low-risk infections may cause genital warts (condylomata acuminata) or warts on the hands and feet (plantar warts). High-risk infections are usually silent until they cause precancerous lesions, which can develop into invasive cancers over decades. The most significant health effect is cervical cancer, but HPV also causes a substantial proportion of anal, oropharyngeal, penile, vaginal, and vulvar cancers.

Diagnosis and screening

There is no routine test for the virus itself in asymptomatic individuals. Screening focuses on detecting cellular changes caused by high-risk types. The primary method is the Papanicolaou test (Pap smear), often combined with DNA testing for high-risk HPV types (co-testing). The U.S. Preventive Services Task Force provides guidelines for screening intervals. For visible anogenital warts, diagnosis is usually clinical. Suspicious lesions are confirmed via biopsy and histopathological examination, which may show features of koilocytosis. Colposcopy is used for magnified examination of the cervix following an abnormal screening test.

Prevention and vaccination

Primary prevention is achieved through prophylactic vaccination. Major vaccines include Gardasil and Cervarix, which protect against high-risk types 16 and 18, and Gardasil 9, which protects against five additional high-risk types and the main low-risk types. The Advisory Committee on Immunization Practices recommends routine vaccination for adolescents. Secondary prevention involves regular cervical screening per guidelines from organizations like the American Cancer Society. Other measures include consistent condom use, which reduces but does not eliminate risk, and male circumcision, which has been shown to lower transmission rates.

Treatment and management

There is no treatment for the virus itself; management targets the lesions it causes. For external anogenital warts, options include patient-applied therapies like imiquimod or podophyllotoxin, or provider-administered cryotherapy, trichloroacetic acid, or surgical removal. Precancerous cervical lesions (cervical intraepithelial neoplasia) may be treated with procedures like loop electrosurgical excision procedure (LEEP) or cold knife conization. Treatment for HPV-related cancers involves standard oncology modalities such as surgery, radiation therapy, and chemotherapy, often guided by institutions like the National Comprehensive Cancer Network. Follow-up after treatment for precancer involves intensified surveillance with Pap tests and HPV tests. Category:Sexually transmitted diseases and infections Category:DNA viruses Category:Gynaecologic cancer