Early enteroviral meningitis can look bacterial in CSF because it may initially show a neutrophilic (PMN) pleocytosis. This usually shifts to lymphocyte predominance within 12 to 48 hours.

This can also occur with mumps and occasionally HSV/VZV meningitis, but the classic exam answer is early viral meningitis, especially enterovirus.

Do not rule out bacterial meningitis only because viral disease is suspected. Bacterial CSF is more likely with markedly low glucose, very high neutrophil count, high protein, positive Gram stain/culture, or a clinically toxic patient.