Understanding genital warts: epidemiology, pathogenesis, and burden of disease of human papillomavirus

As the most commonly sexually transmitted disease worldwide, human papillomavirus (HPV) infections are associated with significant morbidity and mortality. HPV infections most commonly affect young adults, women under 25 in particular. The most common risk factor for HPV infection in both sexes is a high number of lifetime sexual partners, whereas leading protective factors include circumcision, consistent condom use, and abstinence. Over 100 HPV types have been identified to date and are classified according to their level of oncogenic potential. HPV types 6 and 11 are responsible for approximately 90% of genital warts; HPV types 16 and 18 are responsible for 70% of invasive cervical cancers. External genital warts (EGWs) are the most common clinical manifestation of nononcogenic HPV infection. Coinfection with multiple HPV types is possible and may combine both low- and high-risk types, even in cases of genital warts. HPV infections are DNA viruses transmitted through skin-to-skin contact, invading the basal epithelial cells via microtears and evading the host immune response. Although non-life threatening, even low-risk HPV-type infections such as EGW carry a substantial psychosocial and economic burden. Stressors include the shame and embarrassment related to diagnosis, as well as the inconvenience and discomfort of treatment and the fear of recurrence, transmission, and the possible threat of cancer. Costs relate to routine screening for cervical cancer, treatment of genital warts, and the management and follow-up of malignancies.