What is the diagnostic workup for Herpes Simplex Virus (HSV) infection?

From the Guidelines

The diagnosis of Herpes Simplex Virus (HSV) infection should involve a combination of clinical evaluation and laboratory testing, with the preferred diagnostic test being nucleic acid amplification test (NAAT) or polymerase chain reaction (PCR) testing of fluid collected from active vesicles or ulcers, as it has a sensitivity and specificity of >90% 1. When diagnosing HSV infection, the following steps should be taken:

• For suspected HSV lesions, NAAT/PCR testing is the preferred method, as it is more sensitive than viral culture and can detect viral DNA even when the virus cannot be isolated in culture 1.
• If NAAT/PCR is not available, viral culture can be used, but it is less sensitive and may require further investigation through serology if results are negative 1.
• Serologic testing may be useful to detect HSV-1 or HSV-2 antibodies, with type-specific glycoprotein G-based assays being preferred for their ability to distinguish between HSV-1 and HSV-2, but it is essential to note that these tests have limitations, including false-negative results for HSV-1 and false-positive results for HSV-2 1.
• The Tzanck smear and direct immunofluorescence assay are not recommended for diagnosis of HSV genital ulcer disease due to their lack of sensitivity 1. Key considerations in the diagnosis of HSV infection include:
• Timing of testing: testing should ideally be performed within 48-72 hours of lesion appearance before healing begins to avoid false negatives 1.
• Sample collection: adequate sample collection is crucial to avoid false negatives 1.
• Test characteristics: providers should be aware of the test characteristics of HSV NAATs that are performed in their clinical setting, including sensitivity and specificity 1.

From the Research

Diagnosis Workup for HSV

The diagnosis workup for Herpes Simplex Virus (HSV) involves various laboratory and point-of-care techniques. The following are some of the key methods used:

• Type-specific testing: to distinguish HSV-1 from HSV-2, which is essential for prognosis and counseling 2, 3
• Polymerase Chain Reaction (PCR): a highly sensitive and specific method for detecting HSV DNA in clinical samples, particularly in cases of central nervous system infections or genital herpes 2, 3, 4, 5
• Viral culture: although traditionally used for diagnosing genital herpes, it has a lower sensitivity compared to PCR 2
• Antigen detection: using immunofluorescence or enzyme immunoassay, which can be employed for detecting HSV antigens in clinical samples 2, 3
• Type-specific serology: based on glycoprotein G, which is useful for detecting asymptomatic individuals, but not recommended for widespread screening 2, 3
• Point-of-care techniques: such as microfluidics-based tests, which enable on-spot testing and rapid diagnosis 6

Laboratory Techniques

Laboratory techniques for diagnosing HSV include:

• Biochemical assays: such as enzyme-linked immunosorbent assay (ELISA) 5
• Microscopy: for detecting HSV-infected cells 6
• Nucleic acid amplification: such as PCR, which is a highly sensitive and specific method for detecting HSV DNA 2, 3, 4, 5

Point-of-Care Techniques

Point-of-care techniques for diagnosing HSV include:

• Microfluidics-based tests: which enable on-spot testing and rapid diagnosis 6
• Rapid diagnostic tests: which can provide quick and accurate results, but may have lower sensitivity and specificity compared to laboratory-based tests 6