Transmission Sexually transmitted HPV is divided into two categories: low-risk and high-risk. Low-risk HPVs<unk> warts on or around the genitals. Type 6 and 11<unk> 90% of all genital warts and recurrent respiratory papillomatosis that<unk>  benign tumors in the air passages. High-risk HPVs<unk> cancer and consist of about a dozen identified types. Types 16 and 18 are responsible for causing most of HPV-caused cancers. These high-risk HPVs<unk> 5% of the cancers in the world. In the United States, high-risk HPVs<unk> 3% of all cancer<unk>  in women and 2% in men. Risk factors for persistent genital HPV infections, which increases the risk for developing cancer, include early age of first sexual intercourse, multiple partners, smoking, and immunosuppression. Genital HPV is spread by sustained direct skin-to-skin contact, with vaginal, anal, and oral sex being the most common methods. Occasionally it can spread from a mother to her baby during pregnancy. HPV is difficult to remove via standard hospital disinfection techniques, and may be transmitted in a healthcare setting on re-usable gynecological equipment, such as vaginal ultrasound transducers. The period of communicability is still unknown, but probably at least as long as visible HPV lesions persist. HPV may still be transmitted even after lesions are treated and no longer visible or present. Perinatal Although genital HPV types can be transmitted from mother to child during birth, the appearance of genital HPV-related diseases in newborns is rare. However, the lack of appearance does not rule out asymptomatic latent infection, as the virus has proven to be capable of hiding for decades. Perinatal transmission of HPV types 6 and 11 can result in the development of juvenile-onset recurrent respiratory papillomatosis (JORRP). JORRP is very rare, with rates of about 2<unk>  per 100,000 children in the United States. Although JORRP rates are substantially higher if a woman presents with genital warts at the time of giving birth, the risk of JORRP in such<unk>  is still less than 1%. Genital infections Genital HPV infections are transmitted primarily by contact with the genitals, anus, or mouth of an infected sexual partner. Of the 120 known human papilloma viruses, 51 species and three subtypes infect the genital mucosa. Fifteen are classified as high-risk types (16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 68, 73, and 82), three as probable high-risk (26, 53, and 66), and twelve as low-risk (6, 11, 40, 42, 43, 44, 54, 61, 70, 72, 81, and 89). Condoms do not completely protect from the virus because the areas around the genitals including the inner thigh area are not covered, thus exposing these areas to the infected person's skin. Hands Studies have shown HPV transmission between hands and genitals of the same person and sexual partners. Hernandez tested the genitals and dominant hand of each person in twenty-five heterosexual couples every other month for an average of seven months. She found two couples where the man's genitals infected the woman's hand with high-risk HPV, two where her hand infected his genitals, one where her genitals infected his hand, two each where he infected his own hand, and she infected her own hand. Hands were not the main source of transmission in these twenty-five couples, but they were significant. Partridge reports men's fingertips became positive for high risk HPV at more than half the rate (26% per two years) as their genitals (48%). Winer reports 14% of fingertip samples from sexually active women were positive. Non-sexual hand contact seems to have little or no role in HPV transmission. Winer found all fourteen fingertip samples from virgin women negative at the start of her fingertip study. In a separate report on genital HPV infection, 1% of virgin women (1 of 76) with no sexual contact tested positive for HPV, while 10% of virgin women reporting non-penetrative sexual contact were positive (7 of 72). Shared objects Sharing of possibly contaminated objects, for example, razors, may transmit HPV. Although possible, transmission by routes other than sexual intercourse is less common for female genital HPV infection. Fingers-genital contact is a possible way of transmission but unlikely to be a significant source. Blood Though it has traditionally been assumed that HPV is not transmissible via blood—as it is thought to only infect cutaneous and mucosal tissues—recent studies have called this notion into question. Historically, HPV DNA has been detected in the blood of<unk>  cancer patients. In 2005, a group reported that, in frozen blood samples of 57 sexually naive pediatric patients who had vertical or transfusion-acquired HIV infection, 8 (14.0%) of these samples also tested positive for HPV-16. This seems to indicate that it may be possible for HPV to be transmitted via blood transfusion. However, as non-sexual transmission of HPV by other means is not uncommon, this could not be definitively proven. In 2009, a group tested Australian Red Cross blood samples from 180 healthy male donors for HPV, and subsequently found DNA of one or more strains of the virus in 15 (8.3%) of the samples. However, it is important to note that detecting the presence of HPV DNA in blood is not the same as detecting the virus itself in blood, and whether or not the virus itself can or does reside in blood in infected individuals is still unknown. As such, it remains to be determined whether HPV can or cannot be transmitted via blood. This is of concern, as blood donations are not currently screened for HPV, and at least some organizations such as the American Red Cross and other Red Cross societies do not presently appear to disallow HPV-positive individuals from donating blood. Surgery Hospital transmission of HPV, especially to surgical staff, has been documented. Surgeons, including urologists and/or anyone in the room, is subject to HPV infection by inhalation of noxious viral particles during electrocautery or laser ablation of a condyloma (wart). There has been a case report of a laser surgeon who developed extensive laryngeal papillomatosis after providing laser ablation to patients with anogenital condylomata. Virology Cryo-electron microscopy structure of the HPV type 16 viral capsid protein. Rendered from HPV infection is limited to the basal cells of stratified epithelium, the only tissue in which they replicate. The virus cannot bind to live tissue; instead, it infects epithelial tissues through micro-abrasions or other epithelial trauma that exposes segments of the basement membrane. The infectious process is slow, taking 12–24 hours for initiation of transcription. It is believed that involved antibodies play a major neutralizing role while the virions still reside on the basement membrane and cell surfaces. HPV lesions are thought to arise from the proliferation of infected basal keratinocytes. Infection typically occurs when basal cells in the host are exposed to the infectious virus through a disturbed epithelial barrier as would occur during sexual intercourse or after minor skin abrasions. HPV infections have not been shown to be cytolytic; rather, viral particles are released as a result of degeneration of desquamating cells. HPV can survive for many months and at low temperatures without a host; therefore, an individual with plantar warts can spread the virus by walking barefoot. HPV is a small double-stranded circular DNA virus with a genome of approximately 8000 base pairs. The HPV life cycle strictly follows the differentiation program of the host keratinocyte. It is thought that the HPV virion infects epithelial tissues through micro-abrasions, whereby the virion associates with putative receptors such as alpha integrins, laminins, and annexin A2 leading to entry of the virions into basal epithelial cells through clathrin-mediated endocytosis and/or caveolin-mediated endocytosis depending on the type of HPV. At this point, the viral genome is transported to the nucleus by unknown mechanisms and establishes itself at a copy number of 10-200 viral genomes per cell. A sophisticated transcriptional cascade then occurs as the host keratinocyte begins to divide and become increasingly differentiated in the upper layers of the epithelium. Evolution The phylogeny of the various strains of HPV generally reflects the migration patterns of Homo sapiens and suggests that HPV may have diversified along with the human population. Studies suggest that HPV evolved along five major branches that reflect the ethnicity of human hosts, and diversified along with the human population. Researchers initially identified two major variants of HPV16, European (HPV16-E), and Non-European (HPV16-NE). More recent analyses based on thousands of HPV16 genomes show that indeed two major clades exist, that are further subdivided into four lineages (designated A-D) and even further subdivided into 16 sublineages (A1–4, B1–4, C1–4 and D1–4). The A1-A3 sublineages constitute the European variant, A4 the Asian variant, B1-B4 the African type I variant, C1–C4 the African type II variant, D1 the North American variant, D2 the Asian American type I variant, D3 the Asian American type II variant. The various lineages and sublineages have different oncogenic capacity, where overall, the non-European lineages are considered to increase the risk for cancer. Although HPV16 is a DNA virus, there are signs of recombination among the different lineages. Based on
causes of Cervical cancer
risks of Appendix cancer
medical cause of Cervical cancer
risks of Vaginal yeast infection
causes of Endometritis
risks of Pelvic inflammatory disease
types of Skin cancer
symptom of Cervical cancer