Which diagnostic tests should be ordered for a patient with recurrent vaginal herpes simplex virus infection to confirm the diagnosis and screen for co‑existing sexually transmitted infections?

Diagnostic Testing for Recurrent Vaginal HSV

For a patient with recurrent vaginal herpes, obtain a swab from any active lesions for nucleic acid amplification testing (NAAT/PCR) with HSV typing, and simultaneously screen for co-existing sexually transmitted infections including chlamydia, gonorrhea, syphilis, and HIV. 1, 2

Primary Diagnostic Test for HSV Confirmation

NAAT/PCR with HSV typing is the gold standard for diagnosing recurrent genital herpes, providing >90% sensitivity and specificity even for ulcerative or healing lesions where viral culture performs poorly. 1, 3, 4 This test is critical because:

• HSV-2 recurs in 90% of patients within 12 months versus only 55% for HSV-1, making viral typing essential for accurate prognostic counseling. 1
• PCR consistently detects HSV at substantially higher rates than viral culture, particularly in recurrent episodes where viral load is lower. 3, 4, 5

Specimen Collection Technique

When active lesions are present:

• Open vesicles with a sterile needle and collect vesicular fluid with a cotton-wool or Dacron swab, then vigorously swab the base of the lesion to obtain epithelial cells. 6, 1, 7
• Collect specimens as early as possible in the disease course—vesicular lesions yield significantly higher positivity rates than ulcerative or crusted lesions. 1, 7
• For vaginal involvement without external lesions, collect specimens from the cervix and vaginal wall, as HSV can be isolated from these sites in 88% of women with genital herpes. 1

When Lesions Are Absent

Do not order HSV serology for routine diagnosis of recurrent genital herpes when no lesions are present, as type-specific antibody testing cannot distinguish active infection from past infection and has poor performance characteristics (HSV-1 EIA sensitivity only 70.2%; HSV-2 specificity only 39.8% for index values 1.1–2.9). 1

Mandatory Co-Infection Screening

All patients with genital HSV must be screened for other sexually transmitted infections, as genital ulcerations enhance HIV transmission and co-infections are common. 6, 2

Core STI Panel

• Chlamydia and gonorrhea NAAT from vaginal swab (preferred specimen for women). 6, 2
• Syphilis serology using reverse algorithm: treponemal-specific test (EIA/chemiluminescence) first, followed by RPR confirmation. 6, 2
• Fourth-generation HIV antibody/antigen test (detects infection 2–4 weeks post-exposure versus 3–6 weeks for antibody-only tests). 2
• Trichomonas vaginalis NAAT for sexually active women, especially those <25 years or with multiple partners. 2

Rationale for Comprehensive Screening

• HSV and Treponema pallidum can be recovered from the same lesion, and clinical differentiation is unreliable. 6
• 25–40% of genital infections remain unidentified despite testing, and many infections are acquired from asymptomatic partners. 6
• Inflammatory epithelium from HSV lesions increases HIV transmission risk, making HIV screening essential. 6

Special Populations Requiring Additional Testing

HIV-Positive Patients

Screen for all bacterial STIs (chlamydia, gonorrhea, syphilis, trichomoniasis) every 3–6 months, as co-infection dramatically increases HIV transmission risk. 2

Pregnant Women

• Universal screening for HIV, syphilis, and hepatitis B at first prenatal visit. 2
• Chlamydia and gonorrhea screening if <25 years or at increased risk. 2
• Repeat syphilis testing in third trimester and at delivery for high-risk women. 2

Follow-Up Testing Strategy

Retest for chlamydia and gonorrhea at 3 months after any positive result, regardless of whether partners were treated, due to reinfection rates of 25–40%. 2

Annual screening for chlamydia, gonorrhea, HIV, and syphilis is recommended for all sexually active women <25 years, with more frequent testing (every 3–6 months) for those with ongoing high-risk behaviors. 2

Common Pitfalls to Avoid

• Never rely on clinical diagnosis alone—80–90% of genital herpes progresses subclinically, and clinical findings are neither sensitive nor specific. 6
• Do not use viral culture as first-line testing—it is substantially less sensitive than NAAT, particularly for recurrent or ulcerative lesions. 1, 3, 4
• Do not order Tzanck smear—it has low sensitivity/specificity and cannot differentiate HSV from VZV. 7
• Do not skip extragenital testing in high-risk populations—rectal and pharyngeal infections are frequently asymptomatic. 6, 2
• Do not forget partner notification and treatment—most "treatment failures" are actually reinfections from untreated partners. 6, 2

Public Health Reporting

Syphilis, gonorrhea, chlamydia, and HIV are reportable diseases in all states; consult local health department for specific reporting requirements and partner services. 2