Herpes Testing
Understanding the HSV IgG Blood Test
The IgG blood test is commonly used to diagnose herpes simplex virus (HSV) infections. Rather than detecting the virus itself, this test identifies IgG antibodies, which are immune proteins your body produces in response to the HSV infection.
What Does an IgG Test Detect?
Antibodies, such as IgG, are created by the immune system to target specific pathogens like viruses or bacteria. HSV IgG antibodies are produced when a herpes infection occurs and remain in the body for life, serving as markers of both current and past infections.
- HSV-1: Typically associated with cold sores.
- HSV-2: Primarily causes genital herpes.
The HSV IgG test is most commonly used to confirm genital herpes but is not recommended as a routine screening test for the general population. It is, however, advised for pregnant women at risk of genital herpes, as treatment can reduce the risk of transmission to the baby.
Key Points About HSV IgG Testing
-
Timeframe for Antibody Detection
IgG antibodies take about 3–6 weeks after the initial infection to reach detectable levels. Testing too early may result in a false-negative result. -
Testing Guidelines
The Centers for Disease Control and Prevention (CDC) advises against HSV testing for asymptomatic individuals, as it does not alter sexual behavior or significantly reduce transmission rates. -
Accuracy in Differentiating HSV Types
The IgG test is preferred over other antibody tests because it accurately distinguishes between HSV-1 and HSV-2 infections.
IgG vs. IgM Antibody Tests
In addition to IgG testing, an IgM test is sometimes used to detect HSV. Here’s how they differ:
- IgG Antibodies:
- Develop more slowly but remain in the body for a lifetime.
- Useful for identifying past or long-term infections.
- IgM Antibodies:
- Appear early during active or recent infections.
- Disappear within a few weeks, making them less useful for diagnosing past infections.
Interpreting Combined IgG and IgM Results
- Positive IgG and IgM: Likely indicates a new infection.
- Positive IgG only: Indicates a long-standing infection present for at least two months.
- Positive IgM only: Suggests a recent infection.
Note: Between 30% and 70% of people with recurrent infections may also test positive for IgM.
HSV IgG Test Results
Your test results will generally fall into one of three categories:
- Positive: IgG antibodies are detected, indicating a current or past HSV infection.
- Negative: No IgG antibodies are detected, meaning you have likely never been infected with HSV.
- Equivocal: Results are unclear; a repeat test may be recommended after 4–6 weeks.
Accuracy and Limitations of the IgG Test
-
False-Negative Results:
If the test is conducted too soon after exposure, IgG antibodies may not have developed yet, leading to a false-negative result. -
False-Positive Results:
Occasionally, a test may incorrectly report the presence of antibodies, suggesting an infection when none exists.
If your results seem inconsistent with your symptoms or potential exposure, your healthcare provider may suggest additional testing or a repeat IgG test to confirm the diagnosis.
Next Steps After Testing
- If your IgG test is positive, your doctor will review your medical history and symptoms to confirm the diagnosis.
- For equivocal results or suspected recent exposure, a follow-up test may be needed.
Treatment options vary based on whether the infection is active or recurrent. Managing HSV includes antiviral medications to reduce symptom severity, frequency of outbreaks, and the risk of transmission.
By understanding the purpose and limitations of the HSV IgG test, you can work with your healthcare provider to ensure accurate diagnosis and effective management of herpes simplex virus infections.
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Biomarkers included in this panel:
This assay utilizes recombinant type-specific antigens to differentiate HSV-1 from HSV-2 infections. A index positive result cannot distinguish between recent and past infection. If recent HSV infection is suspected but the results are negative or eq
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