Sexually transmitted diseases

The term ‘sexually transmitted diseases (STDs)' refers to a number of distinct infections caused by a variety of organisms, including bacteria, viruses, protozoa, and ectoparasites, which are typically transmitted through sexual contact and result in an array of clinical manifestations. The clinical syndromes associated with infection by one or more of these organisms can range from asymptomatic infection to severe life-threatening disease. The acquisition and transmission of STDs depend primarily on sexual behavior, but some infections, such as hepatitis B and cytomegalovirus, can also be acquired through nonsexual contact in areas with poor living conditions. Some can be transmitted from mother to child during pregnancy and childbirth, and can be sometimes associated with significant infant morbidity and mortality. Others, including syphilis and human immunodeficiency virus (HIV), can be transmitted through blood products and organ transplantation. Over the last two decades, there have been tremendous advances in our understanding of STDs. These include recognition of new pathogens, new clinical syndromes, emerging antimicrobial resistance, the increasing importance of viral pathogens, and a better understanding of the epidemiology of many STDs, and progress has been made in the field of prevention including vaccine development. This article summarizes some important epidemiological trends among the more common STDs, and reviews the clinical syndromes, diagnosis, treatment, and pathogenesis of selected STDs.