From the Guidelines
A positive dengue IgG test result indicates that you have been infected with the dengue virus at some point in the past, and it does not necessarily mean you are currently sick with dengue fever. IgG antibodies typically develop about 7-10 days after infection and can remain in your bloodstream for years or even life 1. This positive result suggests you have immunity to the specific dengue serotype that infected you, but it does not protect you from the other three dengue serotypes. In fact, a second infection with a different serotype can potentially lead to more severe disease through a process called antibody-dependent enhancement. If you're experiencing current symptoms like fever, headache, muscle pain, or rash, additional testing like dengue IgM or NS1 antigen tests would be needed to determine if you have an active infection 1.
Some key points to consider:
- A positive IgG result alone is primarily useful for confirming past exposure or for epidemiological studies tracking dengue prevalence in communities.
- Dengue and Zika virus diagnostic testing employs both molecular and serologic methods, and testing for dengue virus also includes detection of NS1 antigen 1.
- The interpretation of test results should take into account the clinical presentation, epidemiologic history, and laboratory results, including NAAT, IgM antibody, and PRNT tests 1.
- It's essential to understand that there are four different dengue serotypes, and having antibodies to one type doesn't protect you from the others.
Overall, a positive dengue IgG test result provides valuable information about past exposure to the dengue virus, but it does not necessarily indicate current infection or immunity to all dengue serotypes.
From the Research
Interpretation of Positive Dengue Immunoglobulin G (IgG) Test Result
A positive Dengue Immunoglobulin G (IgG) test result can indicate:
- Past exposure to the dengue virus 2, 3, 4
- Current infection, especially in the absence of IgM antibodies or NS1 antigen 2
- Secondary dengue infection, as IgG antibodies are typically present in higher levels in secondary infections than in primary infections 3, 4
Key Findings
- A study published in the Iranian journal of microbiology found that a high IgG index value is more likely to indicate true dengue infection than past exposure 2
- Research published in the Revista da Sociedade Brasileira de Medicina Tropical found that positive IgG plus either positive or negative IgM results indicated recent secondary infections 3
- A study in the Journal of clinical microbiology found that a rapid immunochromatographic test for IgM and IgG antibodies to dengue viruses was able to distinguish between primary and secondary dengue virus infections 4
Diagnostic Considerations
- The presence of IgG antibodies can be used to diagnose dengue infection, but it is essential to consider the clinical context and other laboratory results, such as IgM antibodies and NS1 antigen 2, 5
- A positive IgG test result should be interpreted in conjunction with other diagnostic tests, such as complete blood picture (CBC) and NS1 antigen testing 5