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  • All sexually transmitted diseases (STDs) have subclinical or latent periods, and patients may be asymptomatic.

  • Simultaneous infection with several organisms is common.

  • All patients who seek STD testing should be screened for syphilis and HIV.

  • Partner notification and treatment are important to prevent further transmission and reinfection of the index case.


The most common STDs are gonorrhea,* syphilis,* HPV-associated condyloma acuminatum, chlamydial genital infections,* herpesvirus genital infections, trichomonas vaginitis, chancroid,* granuloma inguinale, scabies, louse infestation, and bacterial vaginosis (among women who have sex with women). However, shigellosis*; hepatitis A, B, and C*; amebiasis; giardiasis*; cryptosporidiosis*; salmonellosis*; and campylobacteriosis may also be transmitted by sexual (oral-anal) contact, especially in men who have sex with men. Ebola virus and Zika virus have both been associated with sexual transmission. Both homosexual and heterosexual contact are risk factors for the transmission of HIV (see Chapter 31). All STDs have subclinical or latent phases that play an important role in long-term persistence of the infection or in its transmission from infected (but largely asymptomatic) persons to other contacts. Simultaneous infection by several different agents is common.

Infections typically present in one of several ways, each of which has a defined differential diagnosis, which should prompt appropriate diagnostic tests.

A. Genital Ulcers

Common etiologies include herpes simplex virus, primary syphilis, and chancroid. Other possibilities include lymphogranuloma venereum (see Chapter 33), granuloma inguinale caused by Klebsiella granulomatis (see Chapter 33), as well as lesions caused by infection with Epstein-Barr virus and HIV. Noninfectious causes are Behçet disease (see Chapter 20), neoplasm, trauma, drugs, and irritants.

B. Urethritis With or Without Urethral Discharge

The most common infections causing urethral discharge are Neisseria gonorrhoeae and Chlamydia trachomatis. N gonorrhoeae and C trachomatis are also frequent causes of prostatitis among sexually active men. Other sexually transmitted infections that can cause urethritis include Mycoplasma genitalium and, less commonly, Ureaplasma urealyticum and Trichomonas vaginalis. Noninfectious causes of urethritis include reactive arthritis with associated urethritis.

C. Vaginal Discharge

Common causes of vaginitis are bacterial vaginosis (caused by overgrowth of anaerobes such as Gardnerella vaginalis), candidiasis, and T vaginalis (see Chapter 18). Less common infectious causes of vaginitis include HPV-associated condylomata acuminata and group A streptococcus. Noninfectious causes are physiologic changes related to the menstrual cycle, irritants, and lichen planus. Even though N gonorrhoeae and C trachomatis are frequent causes of cervicitis, they rarely produce vaginal discharge.

*Reportable to public health authorities.


All persons who seek STD testing should undergo routine screening for HIV infection, using rapid ...

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