Diagnosis of Viral Meningitis Cerebrospinal fluid (CSF) analysis (cell count, protein, glucose) Polymerase chain reaction (PCR) of CSF and sometimes IgM Sometimes PCR and / or culture of blood, a throat swab, nasopharyngeal secretions, or stool Diagnosis of viral meningitis is based on analysis of CSF obtained by lumbar puncture (preceded by neuroimaging if increased intracranial pressure or a mass is suspected).