Next, 677,769 cases of gonorrhea were reported in 2020, up 45% from 2016, and 133,945 cases of primary and secondary syphilis, up 52% over the same period. In 2020, congenital syphilis was identified in 2,148 infants, up 235% from 2016. Chlamydia was the most common of these at 1.6 million cases, down 1.2% from 2016. The Centers for Disease Control (CDC) has determined that roughly 2.4 million non-HPV-related STIs were reported in the US in 2020. Worldwide, at least 291 million women have been infected with HPV. HPV types 6 and 11 are very common and are most closely associated with the formation of anogenital warts, while HPV types 16 and 18 are linked to the development of malignancy. HPV is a known cause of cervical and oropharyngeal cancer, but it has also been linked to other, relatively uncommon malignancies such as cancer of the anus, penis, vagina, and vulva. HPV is often asymptomatic, especially in men, but it may cause venereal and anogenital warts. It is so common that the CDC estimates that virtually all sexually active persons who are not vaccinated will become infected at some point. The most common STI in the United States by far is the human papillomavirus or HPV. At any given time, it is estimated that 80% of sexually active people are infected, including 42% of adults 18 to 59 years, while 7% will have oral HPV, and roughly 14 million new cases will be reported yearly. The most common and relevant STIs include the following: (See our companion reference Statpearls article on 'Hepatitis B.') The eight most common STDs include four curable infections (chlamydia, gonorrhea, syphilis, and trichomonas) and four that are treatable but incurable (hepatitis B, herpes simplex virus, HIV, and HPV). Male circumcision appears to significantly reduce the likelihood of acquiring several STIs, including human papillomavirus, genital herpes, and especially HIV, where the infective risk decreases by 50% to 60%.

Specific causative organisms are outlined below. Risk factors that increase the transmission of STIs include having unprotected sexual contact with multiple partners, having a history of STIs, sexual assault, use of alcohol, prostitution, having a sexual partner who has additional concurrent sexual contacts or a prior history of an STI, use of recreational drugs, and intravenous drug use. The presenting condition or disease depends on the specific organism, route, signs, and symptoms of the disease. STIs are more frequently underrecognized and have a higher incidence in medically underserved populations. The etiology of the most common STIs, including symptoms, physical findings, complications, and the burden they place on infected persons and their families, will be reviewed. Sexually transmitted infections (STIs) are a worldwide health problem and should be recognized by all public health agencies. The natural history and patterns of spread of the most common sexually transmitted infections will be discussed as well as disease prevention, evaluation, diagnosis, and treatment. STIs become a concern and burden on healthcare systems, as many infections go untreated and lead to potentially serious complications.

Sexually transmitted infections, previously known as sexually transmitted diseases, involve the transmission of an organism between sexual partners through different routes of sexual contact, either oral, anal, or vaginal. Physicians should use this article as a guide to further enhance their knowledge and help provide a better outcome for their patients.

What are sexually transmitted infections (STIs), and why are they important? This review will detail important points and reference important articles for physicians and other healthcare professionals to use in evaluating and treating patients with signs and symptoms suggestive of sexually transmitted infections.

Most common route of hiv transmission