Sexually transmitted diseases (STDs) are the infections and resulting clinical syndromes caused by >25 infectious organisms.
Sexual activity is the predominant mode of transmission, through genital, anal, or oral mucosal contact.
STDs are among the most common infectious diseases. Annually, an estimated 448 million infections occur worldwide, and 19 million infections occur in the United States. Some STDs are more prevalent in developing countries (chancroid, lymphogranuloma venereum, granuloma inguinale [donovanosis]) or in specific regions (gonorrhea with treatment failure and decreased susceptibility to cephalosporins in East Asia) and may be imported into developed countries by travelers returning from such locales.
Casual sexual relationships occur frequently during travel to foreign countries; 5%–50% of travelers report casual sex with a new partner while abroad. In addition, commercial sex in various destinations, such as Southeast Asia, attracts many foreign travelers. Commercial sex workers in some regions have high rates of STDs, including HIV, and travelers who have sex with them risk acquiring these infections.
Knowledge of the clinical presentation, frequency of infection, and antimicrobial resistance patterns is needed to manage STDs that occur in travelers. Assessing risk for men who have sex with men is important because of the recent increased rates of infectious syphilis, gonorrhea with treatment failure and decreased susceptibility to cephalosporins, and lymphogranuloma venereum in various geographic locations.
Many infections may be asymptomatic (chlamydia, gonorrhea), so screening for these infections at anatomic sites of contact and serologic testing for syphilis should be encouraged among travelers who present in clinic concerned they may have acquired an STD. Any traveler who might have been exposed and who develops vaginal, urethral, or rectal discharge, an unexplained rash or genital lesion, or genital or pelvic pain should be advised to cease sexual activity and promptly seek medical evaluation.
Some systemic infections are acquired through sexual transmission (hepatitis A, hepatitis B, hepatitis C, HIV, syphilis). Because many travelers do not volunteer a history of sexual contact during travel, clinicians should inquire about sexual exposures when caring for returned travelers.
Genital ulcer evaluation should include a serologic test for syphilis, a culture or PCR testing for genital herpes, and a culture for chancroid (if exposure occurred in areas where chancroid is more common, such as Africa, Asia, and Latin America). Lymphadenopathy can accompany genital ulceration with these infections, as well as with lymphogranuloma venereum and donovanosis. Lymphogranuloma venereum should be suspected in a traveler with tender unilateral inguinal or femoral lymphadenopathy or proctocolitis. If painful perianal ulcers are present or mucosal ulcers are detected on anoscopy, a diagnosis of genital herpes or lymphogranuloma venereum should be considered. Genital and lymph node specimens should be tested for Chlamydia trachomatis by culture, direct immunofluorescence, or nucleic acid testing. Donovanosis is endemic in India, Papua New Guinea, central Australia, and southern Africa and is diagnosed with a crush tissue preparation from the lesion.
Testing specimens from the anatomic site of exposure with nucleic acid amplification testing or culture can detect C. trachomatis and Neisseria gonorrhoeae. Culture and antibiotic susceptibility testing should be considered when gonorrhea is suspected, because of geographic differences in antimicrobial susceptibility. Various diagnostic methods are available to identify the cause of an abnormal vaginal discharge, including microscopic evaluation and pH testing of vaginal secretions, DNA probe-based testing, nucleic acid amplification testing, and culture. Anyone who seeks evaluation or treatment for STDs should be screened for HIV infection.
Evaluation, management, and follow-up of STDs should be based on standard guidelines (CDC and the World Health Organization), and the prevalence of antimicrobial resistance in different geographic areas should be considered. Early detection and treatment are important. STDs can often result in serious and long-term complications, including pelvic inflammatory disease, infertility, stillbirths and neonatal infections, genital cancers, and an increased risk for HIV acquisition and transmission.
The prevention and control of STDs are based on education, counseling, early identification, and treatment. Specific messages to avoid acquiring or transmitting STDs should be part of the health advice given to travelers. Abstinence or mutual monogamy is the most reliable way to avoid acquiring and transmitting STDs.
For people whose sexual behaviors place them at risk for STDs, correct and consistent use of the male latex condom can reduce the risk of HIV infection and many common STDs, including chlamydia, gonorrhea, and trichomoniasis. Preventing lower genital tract infections might reduce the risk of pelvic inflammatory disease in women. Condoms might protect against genital herpes, syphilis, and chancroid, although data are limited. Only water-based lubricants (such as K-Y Jelly or glycerin) should be used with latex condoms because oil-based lubricants (such as petroleum jelly, shortening, mineral oil, or massage oil) can weaken latex condoms. Spermicides containing nonoxynol-9 are not recommended for STD/HIV prevention, as nonoxynol-9 can increase the risk of HIV transmission. Contraceptive methods that are not mechanical barriers do not protect against HIV or other STDs.
Prompt evaluation of sexual partners is necessary to prevent reinfection and disrupt transmission of many STDs. Preexposure vaccination is among the most effective methods for preventing some STDs. Two human papillomavirus (HPV) vaccines are available and licensed for girls and women aged 9–26 years to prevent cervical precancers and cancers: the quadrivalent HPV and the bivalent HPV vaccine. The quadrivalent vaccine also prevents genital warts and is recommended for boys and men aged 9–26 years as well as girls and women (see the Human Papillomavirus section in this chapter). Preexposure vaccination against hepatitis A and B is recommended, as these infections can be sexually transmissible. Hepatitis A vaccine is recommended for all unvaccinated injection drug users and sexually active men who have sex with men. Hepatitis B vaccine is recommended for all unvaccinated men who have sex with men, as well as people who have a history of an STD, have had >1 sexual partner in the previous 6 months, use injection drugs, or have a sex partner who uses injection drugs. However, all travelers should be considered candidates for both these vaccines. Travelers, particularly those at high risk for acquiring HIV infection (such as men who have sex with men), may consider discussing preexposure prophylaxis with their health care provider (see www.cdc.gov/hiv/prep).
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