Laura Moy

CRA

Papillomavirus Infections

Papillomaviruses are double-stranded, non-enveloped DNA viruses that belong to the Papovaviridae family.  They are small in size, about 55 nanometers (def).  Papillomaviruses are very common in humans, and can also be found in mammals and reptiles.  Human Papillomavirus (HPV) have over 200 genotypes and may be divided into (1) genotypes that infect the feet, (2) genotypes that infect the hands, (3) genotypes associated with anogenital (def) conditions, and (4) genotypes associated with various cancers. 

Epidemiologic statistics are limited because of the large number of genotypes that exist.  Many types of HPV are fought off by the immune system within 2 years and many are asymptomatic (def), which is why it is spread so easily and unknowingly. 

Genital HPV is the most common STI, or Sexually Transmitted Infection.  Its prevalence has increased dramatically in past decades, and it is estimated that 6.2 million people become infected every year.  HPV infects equal numbers of males and females, but females are more likely to show symptoms.  Only 1% to 5% of the U.S. population shows symptoms of HPV at any given time, but it is believed that 75% of sexually active people have had HPV at some point in their lives.

The most common cancer associated with HPV is cervical cancer.  There is strong evidence that HPV types 16 and 18 are associated with 90% of cervical cancer cases.   Most cases of cervical cancer occur during a woman’s midlife.  About 4,000 women die of cervical cancer per year.  Roughly 25% of mouth cancers, 35% of throat cancers, 40% of vulvar cancers, 40% of penile cancers, 70% of vaginal cancers, and 85% of anal cancers are associated with HPV. 

Papillomaviruses only replicate on surface tissues of the body.  Infection typically occurs on the mucosal epithelium (def) or skin of the airways, anus, mouth or genitals.  Human Papillomavirus transmission can occur by autoinoculation (def) (e.g. scratching common warts), direct contact with a person infected with HPV (skin contact or sexual acts), or indirect contact (e.g. plantar warts from shower floors).  The transmission of HPV between species is extremely rare. 

HPV is largely transmitted through anal and vaginal sex (though it can also be transmitted by oral sex) and the infected partner may not show any signs or symptoms.  It is possible (but rare) for women to transmit their HPV congenitally (def), and JORRP, or Juvenile Onset Recurrent Respiratory Papillomatosis, can then affect these children. 

Cutaneous (def) or common warts (or verrucae vulgaris) are usually seen on keratinzed (def) skin of the knees, fingers, hands or feet.  They look rough and scaly, and may be painful to the touch.  Plantar (or palmoplantar) warts are thick bumps on the hands and feet that can be difficult to treat.  Flat warts (or verrucae plana) usually appear as multiple discolored papules (def).   Oral warts are common, but easily overlooked as they are generally small and painless.  Throat warts may cause a condition called RRP (or Recurrent Respiratory Papillomatosis), which can cause airway blockages and a hoarse voice. 

A couple of genetic conditions involving Human Papillomavirus include Heck Disease and EDV.  Heck Disease (or Focal Epithelial Hyperplasia) is associated with genotypes 32 and 13 and causes oral infection.  EDV (or Epidermodysplasia Verruciformis) increases susceptibility of uncommon types of warts and can affect any part of the body.  This condition typically begins during childhood, but can also affect adult immunosuppressed (def) patients.  Individuals with untreated EDV are at greater risk for developing skin cancer. 

Most people (about 90%) that contract HPV genitally do not develop heath problems or symptoms because the immune system gets rid of it within 2 years.  Genital infections caused by certain genotypes of HPV can appear as a range of warty lesions on the genitals or anus, and may be visible within weeks or months of the sexual encounter with an infected person.  One papule or a group of papules (called condyloma acuminata) may develop into a large cauliflower-shaped mass.  Flat condylomata (def) growths have a white plaque, and giant condyloma (also called Buschke-Lowenstein tumors) resemble cauliflower but also form fistulas (def) and abscesses (def). 

Cervical and other HPV-linked cancers usually do not have signs or symptoms until they are advanced and spreading, which makes them difficult to recognize and treat.  Some general symptoms of these cancers include bleeding, raised lumps or bumps, discoloration, pelvic pain, painful urination, discharge, itching, and bowel changes. 

The only way to prevent Papillomavirus infections on the hands and feet is to avoid contact with the virus.  Precautions may be taken in moist places such as the gym, locker room, or pool area by wearing shoes or sandals.  Washing and sanitizing hands may help spread infection, as well as avoiding contact with existing warts on the body so that they do not spread to other parts of the body.  Warts on the hands and feet may be treated with over-the-counter treatments, usually consisting of salicylic acid that dissolves the protein keratin in thick skin.  Prescription treatments include Blenoxane and Aldara, and surgical removal is also an option.  RRP (causing throat warts) is not necessarily prevented by cesarean (def) delivery, so should instead be treated with medicines or surgery.

Recently, vaccines have been developed to prevent some common genotypes of Human Papillomavirus.  Gardasil is a vaccine designed for males and females ages 9 to 26 to help prevent genital warts.  It stimulates the body’s production of antibodies against infection as a preventive measure in case the body is exposed to the virus.  Cervarix is a vaccine designed for young females to protect against cervical cancers, but only those caused by genotypes 16 and 18.  These vaccines work best if the person gets all 3 injection doses (over a period of 6 months) before becoming sexually active. 

The best prevention for HPV is to avoid sexual activity.  There are no routine screenings that test for HPV-related conditions (except for cervical cancer), and there is no treatment for the Papillomavirus itself.  For the sexually active, condoms may not cover all areas that may be infected with HPV but they should still be used for every sex act.  Limiting the number of sex partners helps lower chances of getting HPV although having only one partner does not ensure avoidance of HPV.  Genital warts may be treated with medications such as Aldara, Condylox, and trichloroacetic acid, or by surgical removal.  About 30% of genital warts go away without treatment. 

Besides vaccines, prevention for cervical cancer also includes screening tests such as the Papanicolau test (or the Pap smear) and the HPV test, both of which may detect changes in cervical cells before they become cancerous.  Other than cervical cancer, there are no screening tests for HPV-related cancers.  Since these cancers have usually progressed by the time they are detected, treatment usually involves chemotherapy and radiation therapy.

Butel, Janet S.  “Papillomaviruses.”  Medical Microbiology.  4th ed.  The University of Texas Medical Branch at Galveston, 1996.  NCBI Bookshelf.  Web.  Retrieved April 12, 2010 from http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=mmed&part=A3498. 

CDC.  Centers for Disease Control and Prevention.  Human Papillomavirus (HPV).  Retrieved April 12, 2010 from http://www.cdc.gov/hpv/index.html. 

Shanley, John D.  Papillomavirus.  Nov. 16, 2009.  eMedicine.com.  Retrieved April 12, 2010 from http://emedicine.medscape.com/article/224516-overview.

Wikipedia contributors. "Papillomaviridae." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 2 Apr. 2010. Web. 12 Apr. 2010.