Sexually Transmitted Diseases

These diseases are incurable, but during the 1980s and 1990s, many technological advances led to improved diagnostic tools, thus enabling a clearer understanding of the distribution of these diseases in the world. For some of the viral STDs, therapies to minimize symptoms exist. Hepatitis B virus (HBV), which is often but not always sexually transmitted, is the only STD for which an effective vaccine has been developed and is readily available.

Herpes simplex virus (HSV) infection. Herpes (from the Greek, to creep) is another STD with a long history. There are two major types of HSV: HSV-1 and HSV-2. Genital herpes, the clinical condition, is most often caused by HSV-2, and caused much less frequently by HSV-1. A prior history of HSV-1 appears to increase the risk of acquiring HSV-2. Herodotus, a Roman physician, described cold sores (from HSV-1) in the second century, and genital herpes was first described by John Astruc, a French physician in the eighteenth century, Shortly thereafter, other physicians noted that genital herpes often afflicted a patient shortly after the onset of syphilis or gonorrhea. Genital herpes results in painful ulcers that last about ten to fourteen days; both men and women can be affected. These ulcers can be treated by antiviral agents to ease discomfort and shorten periods of symptoms, but the infection persists in the body and symptoms are likely to reoccur. HSV-2 is most frequently transmitted by viral shedding from ulcers during sex, but transmission can occur even when no genital ulcer is evident. It can be acquired by the infant from its mother during child birth.

Both HSV-1 (much lower worldwide prevalence) and HSV-2 are widespread throughout the world. Surveys conducted in the United States have led to the approximation that about 20 percent of persons fifteen to seventy-four years of age have antibodies to HSV-2. From a survey conducted in the United States in the early 1990s, it was approximated that 31 million persons living in the United States are infected, as determined by the prevalence of serum antibodies, and it is estimated that approximately 20 to 25 percent of persons living in the United States will contract diagnosable (via symptoms) genital herpes sometime in their lives. Numerous studies have associated the presence of HSV-2 with the lifetime number of sex partners, history of other STDs, and age at first sex (i.e., sexual debut).

Several studies have linked HSV-2 with genital cancers in women (Holmes et al. 1999), and this is an area of intense epidemiological and clinical research. Unlike gonorrhea and syphilis, HSV seems to be distributed homogeneously in the sexually active population. Together with syphilis and chancroid, genital herpes forms a group of diseases called genital ulcer disease because of the dermatological eruptions they can cause. Patients with symptomatic genital herpes can be treated topically with acylovir to moderate severity and duration of symptoms. Most often, genital herpes is a fairly benign STD; however, it can be of urgent concern during pregnancy when there can be danger of transmission of the infection to the newborn. Neonatal herpes causes frequent morbidity and even mortality, but infants who are delivered by cesarean section avoid risk of transmission, as do infants born to women with no recent symptomatic outbreaks.

Human papillomavirus infection (HPV). This disease, most often manifested as genital warts, is the most common viral STD. Although case surveillance of HPV is relatively poor worldwide, physicians report seeing increases in numbers of cases. The wart (condyloma acuminata) that is seen in about 30 percent of all HPV patients is usually a small, pimply tumor, pigmented or nonpigmented, with fingerlike projections. In women with HPV, it is commonly seen in the lower genital tract; in men, it can appear at various sites in the genital region. The presence of HPV in the cervix and vulva is cause for concern. Certain HPV DNA types have been found in more than 90 percent of patients with certain forms of genital tract cancer, and it is therefore thought that the HPV infections caused by these HPV DNA types are precursors of later cancers in women. Although the clinical management of HPV varies greatly, several therapies, including physical agents (e.g., electrocautery) and immunotherapy, are available and widely used.

HIV and other STDs. HIV (technically, also an STD when it is, in fact, sexually transmitted) and AIDS disproportionately affected white homosexual and bisexual men in the early stages of the epidemic (early 1980s) in the United States, but as the epidemic was spread and diagnosed around the world, the epidemiology of the disease varied by geographical region, influenced greatly by cultural differences. In the United States, the epidemic later appeared in subpopulations of injecting drug users, most of whom were members of racial/ethnic minorities. Since 1989, the group in the United States showing the greatest increase in reported HIV infection has been the group infected through heterosexual transmission, especially in subpopulations in which STDs are most prevalent (Wasserheit 1994). Persons with STDs, especially those infected with genital ulcer disease, appear to be at elevated risk for acquiring an HIV from an infected sex partner. A person who is co-infected (HIV and an STD) is also more likely to transmit HIV to a sex partner than one who is infected with HIV alone. Thus, an important strategy for modulating the HIV epidemic throughout the world is the successful prevention of all STDs and the successful treatment of curable STDs.