SCREENINGS AND PREVENTIVE MEASURES
The U.S. Preventive Services Task Force (USPSTF) recommends that sexually active women younger than 25 years of age (including adolescents) have systematic annual screening for chlamydia, HIV, and gonorrhea (USPSTF recommendations for STI screening available at http://www.ahrq.gov/clinic/uspstf08/methods/stinfections.htm). Routine screening for herpes is not recommended because of potential high false-positive rates in low-risk populations.
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Chlamydia and gonorrhea infection rates are highest among females aged 15 to 19 years because adolescents, particularly those younger than the age of 15 years, are at high risk of acquiring STIs. Although biological factors such as cervical ectopy and lower levels of secretory immunoglobulin A (IgA), a local protective antibody in cervical mucus, have been postulated to contribute to this susceptibility, the evidence is not conclusive.
3,4 Recurrent acquisition of STIs is common among adolescents, with many being reinfected within a few months of the index infection. It is estimated that 40% of the reported incidences of chlamydia and gonorrhea occur in adolescents previously infected with the organisms.
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In one study of sexually active adolescent women ages 14 to 17 years, 25% of the adolescents acquired their first STI (most commonly chlamydia) by the age of 15 years, and the median time interval between the first occurrence of intercourse and the first diagnosed STI was 2 years.
6 STI screening for urban adolescent girls is recommended within the first year of sexual intercourse. Most adolescents in the United States can consent to the confidential diagnosis and treatment of STIs without parental consent or knowledge. There are a few states that require parental notification.
Many screening interventions have demonstrated a decline in chlamydial infections and the incidence of PID.
7 Interval screening times for STIs vary. For patients with no history of an STI, the screening interval is based on changes in risk factor(s) or number of sexual partners. It is recommended that women with newly diagnosed chlamydial, gonococcal, or
Trichomonas infections should be rescreened in 3 months to test for new asymptomatic infections. A patient’s sexual history should be included in the screening process to assess individual risk factors for STIs (see
Table 6.11 for the required components of a sexual history for STI screening).
Although the burden of STIs is found primarily in younger populations, STI screenings are also recommended for older women who engage in high-risk sexual behavior. Postmenopausal women may not perceive themselves to be at risk for STIs although there is evidence that STI rates are increasing among older adults. Recent studies have found that the number of STIs among people older than age 45 years in the United Kingdom nearly doubled from 1996 to 2003.
8 From 2004 to 2009 in the United States, the rates of chlamydia infections in women aged 45 to 54 years increased from 23 to 39.3 per 100,000 individuals, whereas syphilis increased from 4.6 to 8.5.
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Patient education and counseling are important tools for preventing STIs. Client-centered counseling in which a patient’s personal risk factors, situations in which the risk(s) occur, and having the patient or client set personal goals are effective in STI prevention. Training in client-centered counseling is available through the Centers for Disease Control and Prevention (CDC)
STD/HIV Prevention Training Centers (http://www.stdhivpreventiontraining.org). Abstinence and a reduction in the number of sexual partners are also reliable methods to avoid STIs. Counseling that encourages abstinence from sexual intercourse during the course of therapy for an STI is recommended.
Consistent use of male condoms reduces the risk for some STIs, including chlamydia, gonorrhea, trichomoniasis, HSV-2, and HPV-associated diseases.
10 In one prospective study among newly sexually active women in college, consistent and correct condom use was associated with a 70% reduction in risk for HPV transmission.
11 Although data are limited, the female condom also reduces the risk of STIs.
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Although proper condom use is effective at preventing STIs, they are not 100% effective at preventing transmission. The rate of condom breakage has been reported to be 0.5 to 3.7% in several prospective studies, and inexperienced users may contribute to condom failure.
13,14 There are two general categories of nonlatex condoms available in the United States. The first type is made of polyurethane or other synthetic material, can be substituted for latex condoms by those with latex allergies, and provides protection against sexually transmitted diseases (STDs)/HIV and pregnancy equal to that of latex condoms.
15 Compared to latex condoms, pregnancy rates among women whose partners use polyurethane or other synthetic condoms are similar, but the polyurethane or other synthetic condoms are more expensive and are reported to have higher slippage and breakage rates than latex condoms.
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The second category of latex condom alternatives is natural membrane condoms (often referred to as natural or “lambskin” condoms). Lamb cecum is often the source for these condoms, and although the pores in these condoms do not allow sperm to pass through, they are more than 10 times the diameter of the HIV virus and 25 times the diameter of the HPV virus. Viral STIs can be transmitted despite use of these condoms, and they are not recommended for the prevention of STIs.
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Condoms lubricated with spermicides are no more effective than other lubricated condoms in protecting against the transmission of HIV and other STDs. Frequent use of nonoxynol-9 (N-9) may actually enhance susceptibility to HIV infection by causing a breakdown of the mucosal barrier.
17 Therefore, use of condoms lubricated with N-9 is not recommended for STD/HIV prevention.
The cervical diaphragm demonstrated effectiveness in reducing cervical gonorrhea, chlamydia, and trichomoniasis transmission in observational studies.
18 Diaphragms alone should not be relied upon for the prevention of HIV transmission. The vaginal contraceptive sponge offers some protection against cervical gonorrhea and chlamydia although use of the sponge has been associated with candidiasis. Vaginal spermicides containing N-9 are not effective in preventing cervical gonorrhea, chlamydia, or HIV.
Pre-exposure vaccination is one of the most effective methods for preventing transmission of several STIs. Hepatitis A virus (HAV), hepatitis B virus (HBV), and some types of HPV can all be effectively prevented with pre-exposure vaccination. Hepatitis A pre-exposure vaccination is recommended for men who have sex with men (MSM), intravenous drug users, and HIV-infected patients. Two vaccines against some types of HPV are available and are discussed more fully in
Chapter 5, Abnormal Cervical Cytology and Human Papillomavirus. The 2006 Advisory Committee on Immunization Practices (ACIP) recommends universal hepatitis B immunization for all unvaccinated adults being evaluated for STIs. Vaccine trials for other STIs are being conducted.
Reporting and notification practices are instrumental in the management of STIs. All states require mandatory reporting of the major STIs to local and state health departments. Syphilis, gonorrhea, chlamydia, chancroid, acute hepatitis B and C, HIV, and AIDS are reportable diseases in every state. Reporting can be carried out by the provider and/or by the testing laboratory depending on state requirements. Clinicians should be aware of local reporting guidelines or should seek out local health departments or state STD programs for guidelines. Disease reporting can also assist in the management of sexual partners. When STI infection is suspected in a patient, all sexual partners should be notified, examined, and treated for the STD. According to the CDC, data are limited as to whether partner notification effectively decreases exposure to STDs or if it reduces the incidence and prevalence of these infections in a community.1 Treatment of partners, however, does decrease the risk of reinfection for the patient, so providers should at least encourage persons with STDs to notify their sex partners and urge them to seek medical evaluation and treatment.
1 When a partner is unlikely to seek treatment for an STD, partnerdelivered patient medication (PDPM) can be used. In three clinical trials, the PDPM approach resulted in reduced prevalences of chlamydia (20%) and gonorrhea (50%) at follow-up.
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21 However, this approach has been criticized because the sexual partner does not receive counseling or screening for other STIs. Clinicians should be aware that PDPM is not legal in all states in the United States.