Which laboratory finding is typically seen in meningitis caused by viral infections?

In cases of viral meningitis, a hallmark laboratory finding is the lymphocytic predominance of white blood cells (WBCs) in the cerebrospinal fluid (CSF). Unlike bacterial meningitis, where neutrophils are typically elevated, viral infections usually lead to an increase in lymphocytes. This shift in the type of white blood cells reflects the body's immune response to viral pathogens.

In viral meningitis, while there may be a moderate increase in the overall WBC count, the predominance of lymphocytes is particularly significant. This finding helps differentiate viral causes of meningitis from bacterial and other types of meningitis, which is critical for appropriate diagnosis and treatment.

The laboratory findings associated with viral meningitis also characteristically show a normal glucose level and only mildly elevated protein levels compared to the pronounced changes seen in bacterial infections. This context reinforces why the lymphocytic predominance is a key identifier of viral meningitis.