From the Guidelines
The false negative rate for Varicella Zoster Virus (VZV) PCR testing can occur, and a negative test result does not exclude the diagnosis of varicella encephalitis. This is because various factors can influence the accuracy of PCR testing, including the timing of sample collection, sample quality, and laboratory techniques 1. According to the guidelines, PCR can detect varicella zoster virus DNA, but a negative test result does not necessarily rule out the diagnosis of varicella encephalitis 1.
Some key points to consider when interpreting VZV PCR results include:
- The presence of CSF varicella zoster virus IgM antibodies may also be present in patients with a negative CSF varicella zoster virus PCR result 1
- The utility of PCR assays for the diagnosis of viral infections, including VZV, has been demonstrated, but false-negative results may occur if hemoglobin or other inhibitors are present in CSF 1
- In cases where VZV infection is strongly suspected clinically despite a negative PCR result, treatment should not be delayed, especially in high-risk patients
It is essential to consider these factors and the clinical presentation of the patient when interpreting VZV PCR results, as a negative result does not entirely exclude the diagnosis of varicella encephalitis 1.
From the Research
VZV PCR False Negative Rate
- The false negative rate of VZV PCR is not directly addressed in the provided studies 2, 3, 4, 5, 6.
- However, a study from 2004 3 compared the sensitivity of direct immunofluorescence, tissue culture, and nested multiplex PCR for detecting VZV in vesicle fluid specimens.
- The study found that PCR was the most sensitive method, detecting VZV in 87.6% of cases, while direct immunofluorescence and tissue culture detected VZV in 76.3% and 73.1% of cases, respectively 3.
- Another study from 2015 6 evaluated the prognostic value of qualitative PCR for VZV DNA in cerebrospinal fluid in patients with neurological manifestations of varicella.
- The study found that qualitative PCR for VZV DNA in cerebrospinal fluid had no prognostic value in patients with neurologic manifestations of varicella 6.
- There is no direct information on the false negative rate of VZV PCR in the provided studies, but the studies suggest that PCR is a sensitive method for detecting VZV 3, 6.