Harrison's Internal Medicine Chapter 124. Sexually Transmitted Infections: Overview and Clinical Approach Classification and Epidemiology Worldwide, most adults acquire at least one sexually transmitted infection (STI), and many remain at risk for complications. Each year, for example, an estimated million persons in the United States acquire a new genital human papillomavirus (HPV) infection, and many of these individuals are at risk for genital neoplasias. Certain STIs, such as syphilis, gonorrhea, HIV infection, hepatitis B, and chancroid, are most concentrated within "core populations" characterized by high rates of partner change, multiple concurrent partners, or "dense," highly connected sexual networks—., involving.
