Worldwide, central nervous system infections such as inflammation of brain (encephalitis), inflammation of meninges (meningitis) and sudden onset of weakness of muscles which maybe infectious in origin result in significant illness and death and healthcare costs. Vast majority of central nervous system infections remain without an identifiable cause. There is also concern about new and emerging infections.

This study thus intends to fill in the gaps in knowledge with regards to central nervous system infections in Singapore to give a thorough description of burden of causes of central nervous system infections and detection of outbreaks of new pathogens. Patients suspected of central nervous system infection will be recruited from 5 restructured Singapore hospitals and their blood and other clinical specimens will be sent for testing. Patients will also be followed up to assess long term outcomes and socio-economic costs of these infections. This will help clinicians, policymakers and public health officials in estimating financial and societal costs of CNs infections in Singapore.

The study aims to:

1. To describe the epidemiology of CNS infections in Singapore.
2. To improve the diagnosis of aetiologies of CNS infections through a systematic clinical, laboratory and neuro-radiological evaluation and extensive diagnostic testing.
3. To evaluate the prognosis, long-term outcomes and socio-economic costs of CNS infections.
4. To establish an archive of biological tissues from patients with encephalitis and CNS infections that can be utilized for future testing for emerging novel pathogens or non-infectious aetiologies.

The study will recruit 400 patients over 2 years from 5 restructured hospitals in Singapore. As this is not a comparative study, sample size was not determined.

The study involves clinical and laboratory data collection. Data will also be collected on quality of life and for health economic analysis. The quality of data and its integrity will be periodically reviewed by the Principal Investigator and members of the study team. All samples stored will be de-identified and all data will be de-identified during analysis.

Inclusion Criteria:

1. Clinical suspicion for Central Nervous system (CNS) infections, OR

2. Any two of the following,

   1. Fever or history of fever (≥ 38 °C) during the presenting illness
   2. Seizures of new onset
   3. Focal neurological deficits
   4. Cerebrospinal fluid white cell count pleocytosis (> 4 White blood cells (WBC)/uL)
   5. Abnormal neuroimaging suggestive of CNS infection.
   6. Abnormal electroencephalogram (EEG) suggestive of CNS infection
   7. Depressed or altered level of consciousness, OR

3. No alternative aetiology for acute paralysis identified (e.g stroke, trauma, myopathy etc)

Exclusion Criteria:

1. Patient or next of kin unwilling to give consent
2. Patients with indwelling ventricular devices such as EVD (external ventricular drain), VP (ventriculo-peritoneal) shunts

Any patient admitted to the hospital and who meets clinical case definition will be recruited in the study.