The Herpes Simplex Virus (HSV) is a highly common infection, existing in two primary forms: HSV-1 (oral cold sores) and HSV-2 (genital herpes). Despite its widespread prevalence, routine screening for HSV in asymptomatic individuals is not standard medical practice in the United States. This absence from typical STI panels is due to technical limitations of the available tests and a lack of clear public health utility in widespread screening. Both the Centers for Disease Control and Prevention (CDC) and the U.S. Preventive Services Task Force (USPSTF) recommend against population-based screening for HSV in people without symptoms.
Understanding the Available HSV Tests
Medical professionals use two approaches to test for HSV. Viral detection is used when a patient has active symptoms like blisters or sores. This involves swabbing the lesion, and tests like Nucleic Acid Amplification Testing (NAAT) directly detect the virus itself, confirming an active infection. While highly accurate for diagnosing an outbreak, these tests cannot determine past exposure if no lesions are present.
The second method is serology, a blood test that looks for antibodies to HSV-1 and HSV-2. Antibodies are immune system proteins produced in response to infection and typically persist for life. Serology, specifically the type-specific IgG antibody test, determines if a person has been previously exposed to the virus, even if they are asymptomatic. This serology test is the focus of the debate regarding routine screening.
Technical Limitations of Antibody Screening
The primary barrier to routine screening is the imperfect nature of standard antibody tests in a broad population. A major technical issue is cross-reactivity, where the test may confuse antibodies for different types of herpes or react to other viruses. This leads to a significant rate of false-positive results, particularly with low-titer results. The USPSTF estimates that nearly one out of every two diagnoses for HSV-2 using widely available serologic tests in the U.S. primary care population could be false.
Another limitation is the “window period” between initial infection and the development of detectable antibodies. It typically takes 12 to 16 weeks after exposure for antibody levels to be reliably detected. A test performed too early can produce a false-negative result, incorrectly reassuring a recently infected person. Furthermore, a positive serology test confirms past exposure but cannot determine whether the infection was acquired recently or decades ago, complicating counseling and patient management.
Lack of Public Health Utility in Routine Screening
Beyond technical flaws, medical organizations argue that routine HSV screening offers little public health benefit. Unlike curable STIs such as chlamydia or syphilis, there is no treatment that eliminates the virus from the body. For an asymptomatic person, a positive diagnosis often does not change the disease course, as antiviral medication is typically reserved for managing outbreaks or reducing transmission risk.
Diagnosing an asymptomatic person carries a substantial risk of psychological harm due to the stigma surrounding herpes. A positive result can cause significant anxiety and distress, potentially impacting personal relationships, which often outweighs the minor clinical benefit. The high cost of population-wide screening and follow-up testing is not justified when actionable information is minimal. Since early detection does not lead to a cure, it is less valuable than screening for other STIs where early treatment is curative.
When Medical Professionals Do Recommend HSV Testing
Despite the recommendation against routine screening, testing for HSV is strongly recommended in specific clinical situations. The most common reason is when a patient presents with symptoms, such as unexplained sores or blisters, requiring a sample taken directly from the lesion to confirm the diagnosis. Targeted antibody screening is also appropriate for individuals with known exposure risk, including those whose partners have been diagnosed or who have multiple sexual partners. Testing is also important during pregnancy for women at risk of acquiring the infection late in gestation, due to the risk of transmission to the neonate.