The US Preventive Services Task Force (USPSTF) has released new recommendations advising against screening for genital herpes simplex virus (HSV) in asymptomatic adolescents and adults, including pregnant women.
The report was released August 2 and updates the 2005 USPSTF recommendations, drawing on "substantial" new evidence about the accuracy of screening tests for HSV-2 infection and "limited" new evidence about its harms and benefits.
"The USPSTF concludes with moderate certainty that the harms outweigh the benefits for population-based [HSV-2] screening in asymptomatic adolescents and adults, including those who are pregnant," the report reads.
Genital HSV infection affects about 15.5% of the US population between ages 14 to 49 years (about one in six people), according to estimates from the Centers for Disease Control and Prevention (CDC) quoted in the report.
Two subtypes of genital herpes infection exist: HSV-1 and HSV-2, the latter of which most commonly causes genital herpes in the United States. Although rates of genital herpes resulting from HSV-1 are increasing in the United States, no screening test exists for this subtype.
RTI International–University of North Carolina Evidence-based Practice Center prepared the report under contract from the Agency for Healthcare Research and Quality (AHRQ). They conducted an evidence review using PubMed/MEDLINE, the Cochrane Library, EMBASE, and trial registries of studies published in English from inception through March 2016. The search identified 18 relevant studies evaluating the benefits and harms of screening and prevention for genital HSV. Recommendations focus on the accuracy of currently available screening tests, effectiveness of early detection and treatment, potential harms of screening and treatment, and net benefit vs potential harms of screening.
Accuracy of Current Tests
The USPSTF concluded there is "adequate" evidence to suggest "no greater than small" potential benefit for screening for genital HSV-2 in asymptomatic adolescents and adults.
Evidence suggests currently available screening tests have low specificity and high false-positive rates. HerpeSelect (Focus Diagnostics), the most widely available screening test in the United States, has a pooled estimate of sensitivity of 99% (95% CI, 97% - 100%) and a pooled estimate of specificity of 83% (95% CI, 72% - 90%). The other available test, Biokit HSV-2 Rapid Test (Biokit USA), has a joint estimate of sensitivity of 84% (95% CI, 73% - 91%) and specificity of 95% (95% CI, 93% - 97%). Its positive predictive value in the general US population may be as low as 75%. The HerpeSelect test has a positive predictive value as low as 50%, meaning that about one in every two tests would be false positives.
No confirmatory test is widely available, and the gold standard Western blot can only be done at a single research lab (the University of Washington Clinical Virology Laboratory).
No studies have looked at the accuracy of HSV screening tests in pregnant women.
Effectiveness of Early Detection and Treatment
Current evidence does not support a benefit for antiviral medication in asymptomatic HSV-2 infection, according to the report. Because of its relatively short asymptomatic period (studies suggest that up to 85% of asymptomatic individuals diagnosed with HSV-2 become symptomatic within 6 months of testing), opportunities for interrupting the transmission cycle and changing the disease course with screening and early treatment are limited.
The USPSTF also found "inadequate" evidence to determine whether suppressive antiviral therapy can decrease the rate of HSV-2 transmission in couples in which one partner is infected and the other is not.
Vertical transmission from an infected mother to her infant during vaginal delivery can be limited by intervention, such as caesarean delivery for women with active genital HSV lesions. Although rare, neonatal HSV infection can cause substantial morbidity and mortality. The effectiveness of antiviral therapy in decreasing vertical transmission of HSV has not been studied in pregnant women and their partners.
Potential Harms of Screening
The large number of false positives expected could result in psychological harms, including anxiety, distress, and relationship difficulties. Antiviral medications also carry potential harms.
To decrease the risk for sexually transmitted infections, the USPSTF recommended "intensive" behavioral counseling for all sexually active adolescents and at-risk adults.
Net Benefit vs Harms of Screening
The USPSTF concludes with "moderate certainty" that the harms outweigh the benefits of screening for genital HSV infection in asymptomatic adolescents and adults, including pregnant women.
"Serologic screening for HSV-2 infection is associated with psychological harms and false-positive test results, particularly in populations that have a low prevalence of HSV-2. Evidence on the benefit of preventive antiviral medications for reducing viral shedding or improving health outcomes (e.g., reducing symptom occurrences) in asymptomatic adults who screen positive for HSV-2 is uncertain. We found no evidence evaluating preventive interventions in pregnant women or adolescents," the report concludes.
The review was funded by the AHRQ.
"Serologic Screening for Genital Herpes Infection: U.S. Preventive Services Task Force Draft Recommendation Statement." AHRQ. Published online August 2, 2016. Full text
