CSF obtained in cases of suspected encephalitis, meningitis and meningoencephalitis—often reveals no evidence of bacteria and unremarkable white blood cell and red blood cell counts, protein and glucose levels. Such patients often are given the diagnosis of “viral meningitis” .
Investigators at the University Estadual de Campinas in Brazil studied CSF from 420 patients with acute neurological syndromes in whom bacterial and fungal cultures were negative.
Using a variety of nucleic acid amplification techniques, they looked for evidence of multiple viruses known to be capable of producing neurological diseases. To avoid contamination and improve accuracy, they used at least two negative controls; conducted each phase of the nucleic acid amplification procedure (NAAT) in different rooms; and included positive controls in each reaction. For HHV-6, only, they used nested PCR.
The results of the study are as follows:
- In this South American country, the most frequently-identified virus in CSF was dengue virus (16.0%).
- HHV-6 was the second most common virus (7.6%).
- Other viruses included: nonpolio enteroviruses (7.1%), Zika virus (5.0%), varicella-zoster virus (1.9%), Epstein-Barr virus (1.0%); yellow fever virus (0.7%); Herpes simplex virus 2 (0.5%); Herpes simplex virus 1 (0.2%); HSV-2 0.5%; human cytomegalovirus (0.2%).
- Meningitis and disturbed consciousness were the most common clinical diagnoses in people whose CSF contained HHV-6.
- When comparing the virus-positive patients to the virus-negative patients, there were no differences in white blood cell and red blood cell counts or the protein and glucose levels
This report adds to the evidence that nucleic acid amplification techniques can be valuable in the diagnosis of various neurological conditions, when conducted carefully to avoid both false positive and false negative results. The value of diagnosing the responsible viral etiologic agent more precisely—in terms of improved treatment and prognostic information—remains to be established in clinical studies.
Read the full article: Leon 2021