What are the pros and cons of Herpes Simplex Virus type 2 (HSV2) testing?

Pros and Cons of HSV-2 Testing

HSV-2 serologic testing can provide valuable diagnostic information for symptomatic individuals and select high-risk populations, but widespread screening is not recommended due to significant test limitations, particularly false-positive results at low index values that can cause unnecessary psychological harm and misdiagnosis. 1, 2

PROS of HSV-2 Testing

Diagnostic Clarity for Symptomatic Patients

• Establishes definitive diagnosis in persons with genital symptoms (classic or atypical) that could be consistent with genital herpes, allowing for appropriate treatment and counseling 1
• Provides type-specific information (HSV-1 vs HSV-2) which is critical for prognosis, as HSV-2 causes more frequent recurrences and subclinical shedding than genital HSV-1 3, 4
• High sensitivity of 92% means most infected individuals will be correctly identified 1

Risk Assessment and Prevention

• Identifies asymptomatic carriers who may unknowingly transmit infection to sexual partners 3, 5
• Allows for counseling about transmission risk, asymptomatic viral shedding, and the potential for recurrent episodes 2, 4
• Enables informed decision-making about suppressive antiviral therapy to reduce transmission risk to partners 3, 2

Targeted Screening Benefits for High-Risk Groups

• Particularly valuable for HIV-positive patients, men who have sex with men, and sexual partners of individuals with known genital herpes 2, 4
• Useful for pregnant women at risk of acquiring HSV close to delivery (though universal pregnancy screening is not recommended) 2, 4
• Helps identify individuals at high risk for STDs who are motivated to reduce sexual risk behavior 6

Long-term Health Management

• HSV-2 is a chronic infection impacting long-term sexual health, making accurate diagnosis important for ongoing management 1, 3
• Positive results persist indefinitely, providing permanent documentation of infection status 3

CONS of HSV-2 Testing

Significant Test Performance Limitations

• Index values of 1.1-2.9 have only 39.8% specificity, meaning more than 60% of low-positive results are false positives 1, 3
• Even index values ≥3.0 have only 78.6% specificity, with false positives documented even above 3.5 1
• Persons with HSV-1 infection are significantly more likely to have false-positive HSV-2 results, especially at low index values 1, 3
• In populations with 12% HSV-2 seroprevalence, the positive predictive value can be as low as 69% for some assays, meaning nearly one in three positive results would be falsely positive 7

Window Period and Timing Issues

• False-negative results occur during the window period of up to 12 weeks after acquisition, requiring repeat testing if recent exposure is suspected 1, 3, 2
• Cannot distinguish between recent and long-standing infections, limiting utility for determining timing of acquisition 3

Need for Confirmatory Testing

• Low positive results (index value <3.0) require confirmation with a second assay using different glycoprotein G antigen to avoid misdiagnosis 1, 3, 2
• Using Biokit HSV-2 rapid assay as confirmatory test improves specificity from 93.2% to 98.7%, but access may be limited 1, 3
• Western blot is the gold standard but has very limited availability in clinical settings 3, 2
• Many providers lack awareness of these limitations and give results without appropriate confirmation 1

Psychological and Social Harms

• False-positive results can cause significant psychological distress, relationship problems, and stigmatization 2
• Diagnosis of HSV-2 carries substantial social stigma even when asymptomatic 7
• May lead to unnecessary treatment and counseling based on incorrect results 1

Limited Clinical Utility in Certain Populations

• USPSTF recommends against screening asymptomatic adolescents and adults with low pretest probability (few lifetime partners, no known HSV-2 positive partners, no genital symptoms) 1, 2
• Universal screening of pregnant women is not recommended 1
• Serological tests alone cannot determine the etiology of a presenting genital lesion with certainty 3

Practical Access Issues

• Confirmatory testing methods (Biokit, Western blot) have limited availability in many clinical settings 1, 3
• Not all commercially available HSV assays perform equally, with some having particularly poor specificity 7
• Requires provider and patient awareness of assay limitations for appropriate interpretation 1

Key Clinical Pitfalls to Avoid

• Never rely on a single positive result with index value <3.0 without confirmatory testing 1, 3
• Do not test within 12 weeks of potential exposure without planning for repeat testing if negative 1, 2
• Avoid widespread screening in low-risk asymptomatic populations where false positives will outnumber true positives 1, 2
• Ensure patients understand test limitations before ordering, particularly the possibility of false-positive results 1