STD: Bacterial

Human papilloma virus (HPV) causes genital warts. There are over 100 subtypes of human papillomaviruses that cause warts, and each type causes warts in a specific part of the body. Over 30 subtypes of HPV cause warts in the anogenital area, and these subtypes are the ones that cause the STD genital warts. Only the HPV that causes genital infection is discussed in this section.

Determining exactly how many people are infected with HPV is difficult, since most infections cause little or no symptoms and frequently go undiagnosed. However, it is estimated that 20 to 40 million Americans were infected with the virus, making it the most frequent viral STD. Among people in the 20 to 24 age group, it is the fastest growing STD. Since HPV causes cervical cancer in women, one way to determine the disease burden is to track cases of cervical cancer. Cases of cervical cancer in the U.S. occur in 14,000 women a year and cause 5000 deaths a year.

Having multiple sexual partners, or having a single sexual partner who has had multiple sexual partners, puts one at higher risk for inoculation with HPV. In addition, adolescents and young adults are at high risk for the disease. These two factors are similar for all STDs. One reason that young women are at particularly high risk has to do with the lack of development of mature epithelium on the cervix. The presence of mature epithelium, a stratified squamous epithelium (versus the glandular endocervical lining called ectropion) is thought to be more protective against sexually transmitted diseases.

HPV itself is a small, double-stranded DNA virus of the papovaviridia family. It is transmitted from person to person during direct sexual contact in which there are microabrasions in the skin or mucosa. There are high rates of transmission following one single exposure. The incubation period of the virus is estimated to be 3 weeks to 20 months or longer, but is usually 4 to 8 weeks. The virus infects stratified squamous epithelial cells and epithelial basal cells found in skin and mucous membranes. It replicates in the nucleus of these cells. The course of the infection is different depending on the subtype of HPV (some are more virulent than others) and the immune status of the host.

HPV can cause benign, premalignant and malignant lesions in both women and men. Benign lesions are typically the visible warts, called condyloma. Condyloma can occur anywhere in the genital area: the vulva, vagina, cervix or anus in a woman, or on the penis, scrotum or anus of a man. Condyloma may be so small as to be invisible to the eye but can also be seen as flesh-colored or pink slightly raised bumps on the skin or mucosal. Some condylomas are almost flat, and are only minimally elevated. Condyloma can also grow to be quite large and can interfere with urination or defecation. They may also cause painful intercourse and itching in women. Men may complain of difficulty urinating or urethral discharge.

The risk of cancer from HPV infection is much higher in women than in men. Women are susceptible to malignant changes due to HPV on the vulva, vagina or on the cervix. Both men and women are at risk of anal cancer as well, if HPV has infected anal mucosa. Women (and men) are typically screened for skin and pigment changes at a health exam. Women also are screened for cervical cancer through the PAP Smear, which is recommended for all sexually active women. Often, women receive a diagnosis of HPV based on cellular changes detectable on their PAP Smears. Women (and less commonly, men) with diagnoses of HPV may be recommended to undergo colposcopy. Colposcopy is simply the use of a high-powered light and microscope to examine the affected tissue in more depth.

Treatment of genital HPV consists of chemical methods, freezing or laser treatment of the tissue infected with HPV. This is done to help any discomfort that might be present, reduce any disfigurement, and, most importantly, prevent the progression to cancer. No treatment will fully eradicate the virus from the host.