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Sexually Transmitted Diseases

Chlamydia trachomatis: This is the most common bacterial STI. In women, the infection is usually silent or mild, but long-term consequences are great. Infection of the fallopian tube leads to recurrent pelvic inflammatory disease (PID) by endogenous flora, chronic pelvic pain, ectopic pregnancy, and infertility. In men, approximately half have symptomatic urethritis and this is the most common cause of epididymitis in young men. Complications include conjunctivitis and reactive arthritis. Treatment with single-dose azithromycin or doxycycline for 1 week is effective in over 95%. Screening asymptomatic women in primary care who have risk factors such as age <25>[8] Screening young symptomatic men at risk is recommended for primary prevention for women.[9] Nucleic-acid amplification (NAAT) has remarkably simplified screening, but has been slow in introduction in industrialized countries and too expensive for routine use in developing countries.

  • Neisseria gonorrhoeae: Symptoms are like those of C trachomatis, but more severe. Community surveys show a "substantial pool of asymptomatic infections in men and women."[10] NAAT testing has shown the reduced sensitivity of culture in some settings, but culture is still the most common method for detection due to low cost and for sensitivity testing. Quinolone resistance is well established, especially in the Asia-Pacific region;[11] the use of ceftriaxone or cefixime is increasingly required.

  • Mycoplasma genitalium: Growing evidence suggests this as a cause of urethritis in men and cervicitis and PID with tubal infertility in women.[12] The suggestion is "a new chlamydia," but this conclusion may be premature. Prevalence is 2-10% and higher in sexual partners of infected persons. NAAT is the only practical diagnostic test.

  • Trichomonas vaginalis: Prevalence rates are highly variable in different populations, most infections are asymptomatic, PCR testing is much more sensitive than microscopy, and major complications include its possible association with preterm birth and promotion of HIV transmission. A trial to determine potential benefit of screening and treating asymptomatic pregnant women to prevent preterm birth was negative.[13]

  • Treponema pallidum: New diagnostic tests include multiple enzyme immunoassay (EIA) tests that are more sensitive and specific than standard tests.[14,15] A multiorganism polymerase chain reaction (PCR) for genital ulcers (for detection of herpes simplex virus [HSV], Haemophilus ducreyi and T pallidum) has been developed, but is not commercially available.[16] There is nothing new in treatment.

  • Human papillomavirus (HPV): A study of US women aged 18-35 years undergoing routine gynecologic care showed an annual incidence of 32% for high risk (type 16, 18, 31 and 45) HPV infection with a median time to spontaneous clearance of 10 months.[17] The prevalence of HPV antibodies is much higher in women than men.[18] Nearly all cervical cancer is associated with HPV,[19] but there appears to be a need for cofactors such as other STIs, increased parity, long-term oral contraception, and/or smoking. A monovalent vaccine to HPV 16 showed success in trials of multivalent vaccine are under way.[20]

  • HSV: Over 25% of the US population harbor genital HSV; most deny symptoms but learned to recognize typical lesions, so the term "undiagnosed HSV" is preferred to "asymptomatic HSV."[21] Global seroprevalence of HSV-2 in adults is 10% to 40%[22] and this is now recognized as probably the most common cause of genital ulcers in developing countries.[23] Type-specific HSV-2 serology is commercially available, but is used as a public health measure; use for routine screening is considered controversial. HSV-2 transmission can be reduced two thirds by educating patients about recognition of clinical symptoms,[24] and it was reduced by 77% with suppressive antiviral treatment.[25]

The major advance in diagnostic studies includes the extensive use of NAATs for STI detection. This development, along with prevalence rates and new treatment directions for the major STDs, are summarized in table 7.

summarizes the estimated direct cost for STI according to Eng and Butler, editors of The Hidden Epidemic: Confronting Sexually Transmitted Diseases.[26]