Optimal Timing for HSV Antibody Testing
The best time to check for HSV antibodies is approximately 12 weeks after potential exposure, as antibodies take 6-12 weeks to develop in sufficient quantities for accurate detection. 1
Understanding HSV Antibody Development Timeline
- HSV-specific IgG antibodies typically develop within several weeks of infection and persist indefinitely, making them useful for determining past exposure 2
- The "window period" for antibody development is approximately 6-12 weeks after exposure, during which false-negative results are common 1
- IgM antibodies appear earlier in infection but have limitations in diagnostic accuracy and interpretation 3
Testing Recommendations by Antibody Type
HSV IgG Testing
- Wait at least 12 weeks after suspected exposure for optimal sensitivity of HSV IgG testing 2
- HSV IgG antibodies persist for life after infection, making them reliable markers of past exposure 4
- Type-specific HSV IgG tests can differentiate between HSV-1 and HSV-2 infections 2
HSV IgM Testing
- HSV IgM antibodies typically peak approximately 1 week after the onset of symptoms 5
- IgM testing has limited utility due to:
Special Testing Considerations
- For suspected HSV encephalitis where CSF PCR was not performed acutely, a CSF sample should be collected approximately 10-14 days after illness onset for HSV-specific IgG antibody testing 6
- Intrathecal synthesis of HSV-specific IgG antibodies is normally detected after 10-14 days of illness, peaks after one month, and can persist for several years 6
- For suspected recent HSV infection with negative initial serology, repeat testing should be performed after the 12-week window period 2
Interpretation of Results
- Low positive HSV-2 IgG results (index values 1.1-2.9) have poor specificity (39.8%) and may require confirmation with a second test using a different glycoprotein G antigen 2
- Higher index values (≥3.0) for HSV-2 IgG have improved specificity (78.6%) 2
- False positives are more common in individuals with HSV-1 infection, especially with low index values 2
Common Pitfalls in HSV Antibody Testing
- Testing too early (before 12 weeks) can lead to false-negative results 1
- Relying solely on IgM for diagnosis has poor negative predictive value (85%) 3
- Serological tests alone cannot determine the etiology of a presenting genital lesion with certainty 2
- Commercial HSV-2 serologic tests have significant specificity limitations, especially at lower index values 2
Remember that antibody testing should be performed in conjunction with clinical evaluation, and consultation with specialists in microbiology, virology, or infectious diseases is recommended when interpreting results 6.