Human papillomavirus (HPV) - virus, infection, symptoms and cervical cancer
HPV and Common Warts
The strains of HPV that cause common warts are mildly contagious and are more likely to spread to different locations on a person’s body rather than to other people. These strains include
- HPV-2, HPV-4, and HPV-7, which cause the raised, rounded warts commonly found on the hands and fingers
- HPV-3 and HPV-7 cause flat, round warts that typically grow on the face and backs of the hands
- HPV-1, which causes plantar warts on the plantar surfaces, or soles, of the feet
Common warts typically do not cause symptoms other than their appearance, which people tend to find cosmetically displeasing. Numerous products and methods are available to remove them. Over time, most warts left on their own gradually recede and disappear as the IMMUNE SYSTEM dispenses with the virus that causes them. Plantar warts, because they are on the walking surface of the foot, often become painful. Plantar warts are also more commonly spread among people, typically via exposure in locker rooms and shower rooms where people walk barefoot.
Genital HPV Infection
Genital HPV INFECTION is the most common of the SEXUALLY TRANSMITTED DISEASES (STDS) in the United States, causing new infection in over 5 million people each year. More than 20 million people currently have HPV infections. More than 40 strains of HPV cause genital HPV infection. These strains are contagious among people and spread via sexual contact (vaginal intercourse, anal intercourse, and oral sex). Some strains produce no symptoms.
HPV-6 and HPV-11 produce fleshy growths, often called genital warts, at the sites where the virus enters the body. Commonly genital warts grow on the tip of the PENIS, on the VULVA and at the opening of the VAGINA, and around the ANUS. Genital warts may also grow within the vagina and on the CERVIX in women and on the SCROTUM in men. Genital HPV may infect the MOUTH and THROAT through oral sex, though this is much less common than genital infection.
Women may first learn they have genital HPV infection during a ROUTINE MEDICAL EXAMINATION when the health-care provider detects genital warts inside the vagina and on the cervix. The gynecologist may perform COLPOSCOPY, an examination of the interior vagina with a specialized microscope, for further diagnostic assessment and to remove tissue samples (biopsy). Genital warts turn white after a few minutes when dabbed with a mild acetic acid solution (vinegar), providing the doctor with a quick diagnostic assessment. Laboratory examination of tissue samples from the growths can confirm the diagnosis.
Because genital warts continue to grow, which both cultivates and sheds the virus, doctors recommend treatment to remove them. Treatment options include medications, cryosurgery (freezing), electrocautery (burning), and laser therapy. Genital warts tend to recur, however, as long as the HPV infection remains present in the body.
|TOPICAL MEDICATIONS TO TREAT HPV GENITAL WARTS|
|bichloracetic acid (BCA)||5-fluorouracil cream|
|imiquimod cream||podofilox solution|
|podophyllin solution||trichloroacetic acid (TCA)|
Most HPV strains that cause genital infection do not produce symptoms. Many of these asymptomatic infections are benign (harmless) and go away in two or three years. Other genital HPV infections cause molecular changes in the cells of tissues. The tissues most commonly affected are the walls of the vagina and the cervix. These changes, called DYSPLASIA, are detectable only through microscopic examination of cells such as the doctor collects for a routine PAP TEST. Though often dysplasia resolves over time without treatment, it may progress to cancer. Doctors generally treat dysplasia to remove the risk for such progression.
Genital HPV Infection and Cancer
In recent years researchers have discovered that nearly all primary cervical cancer tumors contain one or more of 13 strains of HPV. Further, primary cervical cancer rarely occurs in women who have never had HPV infection. Cancer experts now believe HPV infection is the cause of primary cervical cancer. HPV types 16, 18, 31, 33, 39, 45, 51, 52, 56, 58, 59, 68, and 69 are the causative strains; HPV-16 and HPV-18 together account for about 85 percent of cervical cancers. Though these strains of HPV cause cervical cancer, only a small percentage of women infected with them develop cervical cancer. Routine Pap tests are a woman’s best defense against HPV infection leading to cervical cancer because the changes in cells takes place slowly over years. Detecting and treating cervical or vaginal dysplasia eliminates the risk for the cells to continue a transition to cancer.
Preventing HPV Infection
Because human papillomaviruses are so prevalent, avoiding infection is difficult. Minimizing touch with common warts and treating them while they are small reduces the risk for spreading them to other parts of the body. Wearing shower sandals in locker rooms and public showers reduces the risk for contracting HPV-1 infection, which causes plantar warts.
Because of the risk for infection with one of the HPV strains linked with cancer, prevention measures are particularly important for genital HPV infection. Using latex condoms during all sexual activity greatly reduces the likelihood of contact with genital warts as well as with infected tissues that do not show symptoms. Annual Pap tests are essential for sexually active women. Men and women who have multiple sex partners have increased risk for genital HPV infection.
In 2006 the US Food and Drug Adminstration (FDA) approved the first vaccine to prevent infection with HPV types 6, 11, 16, and 18 in women. Administered as three injectons over 6 months, the vaccine appears to be highly effective with minimal side effects. However, the vaccine does not benefit women who already have HPV infection. Health experts recommend women through age 26 receive the HPV vaccine and girls receive HPV vaccine at age 11 or 12.