Human papillomavirus infections: Epidemiology, pathogenesis, and therapy

Background: Human papillomaviruses (HPV) are common human pathogens and are classified into more than 80 different types. These viruses produce benign warts in many cases and aggressive squamous cell carcinomas in other cases. Objective: The goal of this review is to update the reader on the epidemiology, pathogenesis, and therapy of HPV infections. Nonanogenital warts are transmitted by skin-to-skin contact while anogenital warts are usually transmitted sexually. Both types of warts produce much morbidity but rarely undergo malignant transformation. They are commonly treated with surgical or cytodestructive therapy, but immunomodulatory agents, such as imiquimod, have been proven to be very effective in anogenital warts and are being evaluated in nonanogenital warts. Other types of HPV have marked oncogenic potential such that over 99% of all cervical cancers and over 50% of other anogenital cancers are due to infection with oncogenic HPV. Many cofactors, such as cigarette smoking, genetics, and helper viruses, have potential roles in HPV oncogenesis, but their relative contributions are poorly understood. Other control measures for warts and HPV-associated cancers are under study, but the greatest future potential may be from the development of prophylactic and therapeutic vaccines. Conclusions: Infection with HPV is very prevalent as are the clinical manifestations of this family of pathogens. Improved therapies for warts (e.g., imiquimod) have recently become available. Vaccines for HPV offer hope for future interventions for warts as well as for prevention of anogenital malignancies.