Genital Warts 

Until the 19th century, genital warts (GWs) were believed to be a form of syphilis or gonorrhea. The viral etiology of warts was established in 1907 by inoculation of wart filtrates into skin, inducing papillomas at the injection site. Today, condyloma acuminatum, or genital warts, generally is recognized as benign proliferations of the anogenital skin and mucosa that result from infection with human papillomavirus (HPV). The HPV family has at least 84 well-documented genotypes. Some believe that the number of HPV types has already approached 130 or more. Despite the generally benign nature of the proliferations, certain types of HPV can place patients at a high risk for anogenital cancer.^{[1, 2, 3]}

The link between cervical cancer and genital warts was first reported in a Rochester, Minnesota population-based cohort study in 1981.^[2] In 1983, HPV type 16 was implicated in the cause of cervical cancer.

Genital warts are a result of HPV infection, which is believed to be acquired by inoculation of the virus into the epidermis via defects in the epithelium (eg, maceration of the skin). Autoinoculation of virus into opposed lesions is common. Spread of HPV infection is usually through skin-associated virus and not from blood-borne infection. Probably, cell-mediated immunity (CMI) plays a significant role in wart regression; patients with CMI deficiency are particularly susceptible to HPV infection and are notoriously difficult to treat.^[4]

Frequency

United States

Epidemiological studies show genital warts to be the most common sexually transmitted diseases (STDs). The population-based incidence of genital warts was estimated at 106 cases per 100,000 population in Rochester, Minnesota (from 175-1978)^[5] and 160 cases per 100,000 population in Manitoba, Canada (in 1992),^[6] with the highest incidence rate in residents aged 20-24 years.

Figures from 5 Blue Cross/Blue Shield Health Plans projected an incidence of 105 cases per 100,000 population (in 2004).^[7] They estimated 340,000 cases nationwide in 2004, with an economic burden of more than $220 million (USD).^[7] These incidence figures were different from data collected from STD clinics and private practitioners’ offices. Using data from these sources, the US Centers for Disease Control and Prevention (CDC) suggested a much higher estimate of more than 6 million new patients a year in the United States (in 2008) and a prevalence of more than 20 million. For comparison, the CDC estimated 1.6 million people have genital herpes and 1.2 million people have chlamydia/gonorrhea.

According to the "National Disease and Therapeutic Index: United States, 1966–2007, the Initial visits to physicians' offices for STD," the increasing trend of HPV infection, after peaking at 351,000 visits in 1987, went down in the following 10 years. Unfortunately, the increasing trend resumed again and reached the highest level ever in 2006 (422,000 visits) before dropping down to 315,000 in 2007.

International

Genital warts have affected as many as 30 million individuals worldwide.

Mortality/Morbidity

Although anogenital warts generally are benign, their significance is drawn from the increased risk of malignancy secondary to HPV infection. Specifically, HPV types 16, 18, 45, 31, 33, 58, and 52 are associated with the greatest prevalence of anogenital malignancy. Infectivity of anogenital warts may be up to two thirds of sexual contacts. High concordance for the same HPV type has been found among sexual partners.

As many as 20% of patients with genital warts have other sexually transmitted diseases concurrently (Rochester, Minnesota).^[7] In an Australian sexual health clinic, 5% of genital wart patients were found to also have chlamydia and/or gonorrhea.^[8]

Race

In the United States, African Americans have a rate of HPV infection that is 1.5 times higher than their white counterparts.

Sex

In a well-defined population study, the female-to-male ratio has been reported to be 1.4:1.^[5] The CDC reports have demonstrated that this disease affects females more frequently than males.

Age

The highest incidence of genital warts consistently is found in young adults aged 15-25 years. This observation tends to hold true even after adjustment for lifetime number of sexual partners, which itself is a significant risk factor for HPV infection. In a population study, 80% of the individuals who were affected were aged 17-33 years.^[5]