Sexually Transmitted Infections

CDC Yellow Book 2024

Posttravel Evaluation

Author(s): Hilary Reno, Laura Quilter

More than 2 dozen bacterial, viral, and parasitic pathogens can cause sexually transmitted infections (STIs). STIs are among the most common infectious diseases reported worldwide. In 2018, ≈26 million new STI cases were reported in the United States; and in 2016, ≈376 million cases of chlamydia, gonorrhea, syphilis, and trichomonas were reported globally. STIs can be transmitted from person to person during sexual activity involving anal, genital, or oral mucosal contact.

Epidemiology

Casual sex during travel is common; a systematic review showed a 35% prevalence. In addition, some people travel for sex tourism (see Sec. 9, Ch. 12, Sex & Travel). Sex partners abroad might include commercial sex workers among whom STI prevalence is elevated. International travel was an independent risk factor for chlamydia infection in a study conducted at one sexual health clinic. Among travelers, documented risk factors for acquiring STIs or HIV include alcohol and other drug use, longer duration of travel, male gender, and increased number of new partners.

Before travel, counsel travelers at risk of engaging in condomless sex to have condoms available, and provide guidance regarding other risk-modifying behaviors. Providers caring for returning travelers should know where to find current information about global epidemiology and antimicrobial resistance patterns of STIs from national and international public health authorities, such as the Centers for Disease Control and Prevention (CDC) Antibiotic-Resistant Gonorrhea website and World Health Organization (WHO), Gonococcal Antimicrobial Resistance (AMR) Surveillance Programme.

The epidemiology and clinical presentations of common bacterial, viral, and parasitic STIs are shown in Table 11-13, Table 11-14, and Table 11-15, respectively. Ask returning travelers about sexual activity during their trip, and include specific questions about region of travel, sexual partners, types of sexual exposure, and condom use. Assessing risk in men who have sex with men (MSM) is important because they have elevated rates of certain infections, including chlamydia, gonorrhea, lymphogranuloma venereum, and syphilis. Screen travelers seeking an evaluation for STI or with evidence of STI for other common STIs as well as HIV. For patients with HIV infection, provide information on HIV care and treatment services if they are not already receiving care.

Table 11-13 Epidemiology, clinical manifestations, diagnosis, & treatment of select bacterial STIs

STI CAUSATIVE ORGANISM	GEOGRAPHIC DISTRIBUTION	TYPICAL CLINICAL PRESENTATION (OFTEN ASYMPTOMATIC)	INCUBATION PERIOD	DIAGNOSIS	FIRST-LINE THERAPY
Chancroid Haemophilus ducreyi	Regional (Africa, Asia, Caribbean)	Irregular, painful genital ulcer Tender, suppurative inguinal lymphadenopathy	4–7 days	Culture with specialized media	Azithromycin 1 g PO ×1 OR Ceftriaxone 250 mg IM ×1 OR Ciprofloxacin 500 mg PO BID ×3 d OR Erythromycin base 500 mg PO TID ×7 d
Chlamydia Chlamydia trachomatis	Worldwide	Cervicitis Urethritis	7–21 days	NAAT	Doxycycline 100 mg PO BID ×7 d OR Azithromycin 1 g PO ×1
Gonorrhea Neisseria gonorrhoeae	Worldwide	Cervicitis Urethritis	1–14 days	NAAT	Ceftriaxone 500 mg IM ×1
Granuloma inguinale (donovanosis) Klebsiella granulomatis	Southern Africa Australia India Papua New Guinea	Extensive genital ulcerations with granulation and easy bleeding Tender lymphadenopathy	4–28 days	Microscopy shows Donovan bodies in macrophages	Azithromycin 1 g PO weekly ×3 weeks or until resolution OR Azithromycin 500 mg PO daily ×3 weeks or until resolution
Lymphogranuloma venereum Chlamydia trachomatis serovar L1-3	Worldwide	Self-limited ulcer Tender inguinal lymphadenopathy Proctocolitis	3–30 days	NAAT, serology	Doxycycline 100 mg PO BID ×21 d
Syphilis Treponema pallidum	Worldwide	Primary syphilis Typically painless (can be painful) genital ulcer Regional lymphadenopathy Secondary syphilis Maculopapular skin rash	10–90 days	Darkfield microscopy (primary infection) Serology	Benzathine penicillin G 1°, 2°, and early latent infection: 2.4 MU IM ×1 Late latent infection or latent syphilis of unknown duration: 2.4 MU IM weekly ×3 weeks

Abbreviations: BID, twice daily; IM, intramuscularly; MU, million units; NAAT, nucleic acid amplification testing; PO, orally; STI, sexually transmitted infection; TID, 3 times daily.

Table 11-14 Epidemiology, clinical manifestations, diagnosis & treatment of select viral STIs

STI CAUSATIVE ORGANISM	GEOGRAPHIC DISTRIBUTION	TYPICAL CLINICAL PRESENTATION (OFTEN ASYMPTOMATIC)	INCUBATION PERIOD	DIAGNOSIS	FIRST-LINE THERAPY
Hepatitis A Hepatitis A virus	Worldwide	Anorexia Fatigue Jaundice Malaise	28 days	Serology	Supportive care (see Sec. 5, Part 2, Ch. 7, Hepatitis A)
Hepatitis B Hepatitis B virus	Worldwide	Anorexia Fatigue Jaundice Malaise	60–150 days	Serology	Several options available (see Sec. 5, Part 2, Ch. 8, Hepatitis B) Consult with an expert
Hepatitis C Hepatitis C virus	Worldwide	Anorexia Fatigue Jaundice Malaise	15–50 days	Serology	Several options available (see Sec. 5, Part 2, Ch. 9, Hepatitis C) Consult with an expert
Herpes simplex Herpes simplex virus (HSV)	Worldwide	≥1 typically painful (can be painless) genital ulcers	2–7 days	Culture or PCR	Acyclovir 400 mg PO TID ×7–10 d OR Valacyclovir 1 g PO BID ×7–10 d OR Famciclovir 250 mg PO TID ×7–10 d
Genital warts Human papillomavirus (HPV)	Worldwide	Warts	14–240 days	Clinical or pathologic	Topical therapy or removal of lesions

Abbreviations: BID, twice daily; IM, intramuscularly; PCR, polymerase chain reaction; PO, orally; STI, sexually transmitted infection; TID, 3 times daily.

Table 11-15 Epidemiology, clinical manifestations, diagnosis & treatment of select parasitic STIs

STI CAUSATIVE ORGANISM	GEOGRAPHIC DISTRIBUTION	TYPICAL CLINICAL PRESENTATION (OFTEN ASYMPTOMATIC)	INCUBATION PERIOD	DIAGNOSIS	FIRST-LINE THERAPY
TRICHOMONIASIS Trichomonas vaginalis	Worldwide	Vaginal discharge, itching	5–28 days	NAAT	Metronidazole Females: 500 mg PO BID ×7 d Males: 2 g PO ×1 OR Tinidazole 2 g PO ×1 (both females & males)

Abbreviations: BID, twice daily; NAAT, nucleic acid amplification testing; PO, orally; STI, sexually transmitted infection

Clinical Presentation

Because many infections are asymptomatic, assess for chlamydia, gonorrhea, HIV, and syphilis in returning travelers who had sex outside of a monogamous relationship while traveling. Advise any traveler who develops STI symptoms (e.g., rectal, urethral, or vaginal discharge; unexplained rash or genital lesion; genital or pelvic pain) following a sexual exposure to abstain from sex and seek prompt medical evaluation.

Human papillomavirus (HPV) infection is commonly acquired ≤2 years of sexual debut and usually clears spontaneously. Although most STIs involve the genital tract, some (e.g., gonorrhea, herpes, syphilis) also cause disseminated disease. Consider STIs in returning travelers, because infection can result in serious and long-term complications including adverse birth outcomes, cancer (anal and cervical), infertility, pelvic inflammatory disease, and an increased risk for HIV acquisition and transmission.

Mpox

Although not considered an STI, transmission of mpox virus during the 2022 multinational outbreak has been associated with close skin-to-skin contact, including that which occurs during sex. Moreover, some patients have presented with physical findings and/or symptoms that could be consistent with an STI (e.g., anogenital lesions, proctitis, dysuria). In some instances, this has resulted in misdiagnosis and delays in initiating proper medical management. In other cases, patients have been co-infected with mpox virus and an STI. For details on the transmission, epidemiology, and management of mpox during the 2022 mpox outbreak, see Sec. 5, Part 2, Ch. 22, Smallpox & Other Orthopoxvirus-Associated Infections; Sec. 9, Ch. 12, Sex & Travel; and the CDC mpox website.

Treatment

Base STI evaluation, management, and follow-up on the most recent national and international guidelines from CDC and WHO. Because of limited availability of diagnostic testing in many countries, WHO follows a syndromic approach to STI management; in the United States, therefore, following CDC treatment guidelines is preferred. Consider drug resistance if an infection does not respond to first-line therapy. This is particularly relevant in travelers who have a persistent gonococcal infection, given the global spread of multidrug-resistant Neisseria gonorrhoeae.

Prevention

Prevention and control of STIs is based on accurate risk assessment, counseling and education, early identification of asymptomatic infection, and effective treatment of travelers; prompt evaluation and treatment of sex partners also is necessary to prevent reinfection and to disrupt STI transmission. As part of pretravel advice, include specific messages and strategies on how to avoid acquiring or transmitting STIs. Abstinence or mutual monogamy between uninfected partners is the most reliable way to avoid acquiring and transmitting STIs.

For people whose sexual behaviors place them at risk for STIs, correct and consistent use of external or internal latex condoms can reduce the risk for HIV infection and other STIs, including chlamydia, gonorrhea, and trichomoniasis. Preventing lower genital tract infections might reduce the risk for pelvic inflammatory disease in female patients. Correct and consistent use of latex condoms also reduces the risk of chancroid, genital herpes, HPV infection, and syphilis. Advise travelers to use only water-based lubricants with latex condoms, because oil-based lubricants (e.g., massage oil, mineral oil, petroleum jelly, shortening) can weaken latex. Also remind travelers that contraceptive methods that are not mechanical barriers (e.g., oral contraceptives) do not protect against HIV or other STIs, and that spermicides containing nonoxynol-9 do not prevent HIV or STIs.

Preexposure vaccination is among the most effective methods for preventing certain STIs. HPV vaccines, for example, are available and licensed for people ≤45 years of age. Both hepatitis A and hepatitis B can be transmitted sexually (see Sec. 5, Part 2, Ch. 7, Hepatitis A, and Sec. 5, Part 2, Ch. 8, Hepatitis B). The Advisory Committee on Immunization Practices (ACIP) recommends hepatitis B vaccination for all adults aged 19–59 years, and hepatitis A vaccine for MSM. Travelers at risk of acquiring HIV infection might benefit from preexposure prophylaxis (see Sec. 5, Part 2, Ch. 11, Human Immunodeficiency Virus / HIV, and HIV: Pre-Exposure Prophylaxis (PrEP).

CDC Sexually Transmitted Diseases (STDs) website

The following authors contributed to the previous version of this chapter: Jodie Dionne-Odom, Kimberly Workowski

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