From the Guidelines
Quantitative testing for herpes, specifically nucleic acid amplification test (NAAT) or polymerase chain reaction (PCR), is the recommended diagnostic approach for detecting HSV-1 or HSV-2 from a genital ulcer/lesion/suspected HSV outbreak, due to its high sensitivity and specificity, as reported in the 2022 study published in Clinical Infectious Diseases 1.
Key Considerations for Quantitative Testing
- The test should be performed on active lesions within the first 48 hours of an outbreak for optimal results.
- Real-time PCR is the most common quantitative test, which can detect and quantify HSV-1 and HSV-2 viral loads from lesion swabs, blood, cerebrospinal fluid, or other specimens.
- Quantitative testing is particularly valuable for diagnosing herpes encephalitis, neonatal herpes, and in immunocompromised patients where viral load monitoring guides treatment decisions.
Comparison with Other Diagnostic Methods
- HSV culture is less sensitive than NAAT/PCR and should only be used if NAAT/PCR is not available due to cost or laboratory limitations 1.
- Serologic assays can be used to diagnose HSV-1 and HSV-2 infection, but they have limitations, such as false-positive or false-negative results, and should be used in conjunction with NAAT/PCR or other diagnostic methods 1.
- Type-specific HSV serologic assays can differentiate between HSV-1 and HSV-2 infection, but they may not be as sensitive or specific as NAAT/PCR 1.
Clinical Implications
- Quantitative testing provides information about viral burden, which helps clinicians assess disease severity and treatment response.
- The test typically reports results in copies/mL, with higher viral loads generally correlating with more severe symptoms.
- Clinicians should be aware of the test characteristics of HSV NAATs that are performed in their clinical setting and use assays that differentiate between HSV-1 and HSV-2 infection to provide patients with information regarding expected natural history of genital herpes 1.
From the Research
Quantitative Testing for Herpes
- There are various antiviral drugs available for the treatment of herpes simplex and varicella-zoster virus infections, including aciclovir, valaciclovir, and famciclovir 2, 3, 4.
- These drugs have been shown to be effective in reducing the severity and duration of symptoms, as well as preventing the development of complications such as postherpetic neuralgia 2, 3.
- However, the development of resistance to these drugs is a concern, particularly in immunocompromised patients 5, 4.
- Genotypic testing and molecular biology-based systems can be used to diagnose and manage infections caused by drug-resistant viruses 5.
- New antiviral drugs, such as helicase-primase inhibitors, are being developed and show promise in treating herpes simplex and varicella-zoster virus infections 4, 6.
- The use of these new drugs may help to overcome the limitations of currently available treatments, including their low efficacy in controlling pain and postherpetic neuralgia development 4.
Laboratory Diagnosis
- Laboratory diagnosis of herpes simplex and varicella-zoster virus infections can be performed using various methods, including genotypic testing and molecular biology-based systems 5.
- These methods can help to identify drug-resistant viruses and guide treatment decisions 5.
- Next-generation sequencing can be used to detect heterogeneous viral populations and monitor the development of resistance over time 5.
Treatment Options
- Treatment options for herpes simplex and varicella-zoster virus infections include antiviral drugs such as aciclovir, valaciclovir, and famciclovir 2, 3, 4.
- New antiviral drugs, such as helicase-primase inhibitors, are being developed and show promise in treating these infections 4, 6.
- The choice of treatment will depend on the severity and duration of symptoms, as well as the presence of any underlying medical conditions 2, 3, 4.