From the Research
False positive parvovirus B19 IgM results can occur due to several factors, and if suspected, confirmatory testing with parvovirus B19 DNA PCR is recommended. This approach directly detects viral genetic material rather than antibody response, providing a more accurate diagnosis 1. Additionally, testing for IgG antibodies can help determine if the infection is recent or past. Clinical correlation is essential, considering symptoms like rash, joint pain, or anemia alongside laboratory findings.
In pregnant women, where diagnosis accuracy is critical due to potential fetal complications, serial ultrasounds may be warranted even with uncertain serologic results. False positives are more common in patients with rheumatoid factor positivity, systemic lupus erythematosus, or other conditions causing polyclonal B-cell activation 2. The performance of parvovirus B19 IgM enzyme immunoassay has been evaluated, showing a sensitivity and specificity of detection of 89.1 and 99.4%, respectively, with no cross-reactivity observed with rubella or other viral disease IgM 3.
Some key points to consider in the diagnosis and management of suspected false positive parvovirus B19 IgM include:
- The use of parvovirus B19 DNA PCR as a confirmatory test
- Testing for IgG antibodies to determine the timing of the infection
- Clinical correlation with symptoms and other laboratory findings
- Consideration of the patient's immune status and potential for false positives due to cross-reactivity or other factors
- The importance of accurate diagnosis in high-risk groups, such as pregnant women and immunocompromised individuals, as highlighted in studies 4, 5.
If clinical suspicion remains high despite a questionable IgM result, consultation with infectious disease specialists may be beneficial for interpretation and management. This comprehensive approach ensures that patients receive appropriate care based on accurate diagnoses, minimizing the risk of morbidity, mortality, and impact on quality of life.