Table 1.

Case definitions.

Condition	Case definition
Encephalitis	Encephalopathy (altered mental function or change in personality) for >24 hours with no other cause identified and at least two of the following:
	1. ≥ 5 × 106/L leucocytes (WBC) in cerebrospinal fluid (CSF)
	2. new onset of seizures,
	3. new onset of focal neurology,
	4. documented fever >38°C before or within 24 hours after hospitalisation,
	5. EEG findings suggestive of encephalitis and/or
	6. MRI/CT findings suggestive of encephalitis
Aseptic meningitis (ASM)	1. Clinical signs of meningitis (headache, neck stiffness, photophobia and/or fever),
	2. ≥ 5 × 106/L leucocytes in CSF and
	3. culture and microscopy negative CSFa

^aFor patients treated with antibiotics prior to LP, a negative bacterial PCR for common causes of bacterial meningitis was required.