Central Nervous System Infections in Denmark

Definitions of central nervous system infections: For all cases with unproven aetiologies no alternative diagnosis than CNS infection is thought more likely after completed multidisciplinary diagnostic work-up. Viral meningitis inclusion criteria \- All patients have to have a clinical presentation consistent with non-bacterial meningitis (e.g. headache, neck stiffness, photo- or phonophobia, fever) and Cerebrospinal fluid leukocytes\>10 cells/ml Patients with viral meningitis with undetermined pathogen have to have: * CSF leukocytes\> 10/mL and no other more probable diagnosis assessed by the local investigator. In case of doubt, patients are discussed with the DASGIB secretary and chair or at meetings. Bacterial meningitis inclusion criteria - All patients have to have a clinical presentation consistent with bacterial meningitis (e.g. headache, neck stiffness, fever, altered mental status) and Proven bacterial aetiology (CSF or blood culture/DNA based technology or antigen tests) Patients with bacterial meningitis in whom the bacteria cannot not be cultured or identified by DNA-based technologies have to have: \- CSF leukocytes\> 10/mL and no other more probable diagnosis assessed by the local investigator. In case of doubt, patients are discussed with the DASGIB secretary and chair or at meetings. Encephalitis inclusion criteria - All patients have to have a clinical presentation consistent with encephalitis (e.g. headache, fever, focal neurological deficit,…