: Encephalitis or myelitis is defined as the inflammatory or infectious involvement of the cerebral parenchyma or spinal cord. When an infectious origin is suspected, the germ is not always identified. Next-generation sequencing could be used to correct an etiological diagnosis of these severe conditions in Guadeloupe. The rate of cases for which the infectious agent is not identified encourages continued diagnostic efforts, with the objective of identifying new pathogens or emerging pathogens, some of which may be more specific in the tropics.

Encephalitis or myelitis is defined as the inflammatory or infectious involvement of the cerebral parenchyma or spinal cord. When an infectious origin is suspected, the germ is not always identified. In Guadeloupe, a region exposed to arboviruses, these infectious agents are among the causes of acute infectious attacks of the central nervous system. Other bacteria, parasites, or poorly known fungal agents may be responsible for these conditions. An observational study, retrospective over a period of 4 years, carried out at University Hospital of Guadeloupe, on cases of acute infectious attacks of the central nervous system, showed that the pathogen was not found in 45% of cases. Next Generation Sequencing (NGS) allows DNA or RNA sequencing faster and more accurately than other routine methods (serology / PCR). This technique could be used to correct an etiological diagnosis concerning these severe conditions in Guadeloupe, as part of a prospective study. Indeed, we find in the literature, more and more examples of patients suffering from these conditions of origin called "indeterminate", for which an etiological diagnosis is made thanks to the NGS, and sometimes a suitable curative treatment undertaken in the course of. A study of this type would be necessary to obtain exhaustive epidemiological data and to improve understanding of these severe pathologies, the consequences of which, in the short and long term, represent real public health issues. The main objective of the study is to describe, prospectively, the etiologies of acute encephalitis and myelitis at the University Hospital of Guadeloupe by carrying out diagnostic methods which may include NGS in patients without etiological diagnosis after having benefited from a first-line assessment. The secondary objectives are to describe the clinical, paraclinical and epidemiological characteristics of these conditions, and to describe long term outcomes

Inclusion Criteria:

• We selected the following eligibility criteria for patients with acute encephalitis:

  • Patient of at least 28 days of life
  • With acute onset of symptoms for more than 24 hours
  • A major criterion among the following:

• a disorder of consciousness or alertness

• memory disorder

• lethargy

• modification of personal or behavioral disorder, irritability

• confusion, disorientation in time or space

  - At least two of the following minor criteria:

• temperature above 38 ° C

• new onset focal neurological deficit

• epileptic crisis

• biological abnormality of CSF (≥ 5 Leukocytes / mm3, protein ≥ 0.40 g / L)

• partial or general epileptic seizure (s) not attributable to pre-existing epileptic disease and / or a recent focal neurological symptom

• brain imaging suggestive of encephalitis, with EEG abnormalities suggestive of encephalitis

  • And absence of alternative diagnosis (intoxication, metabolic encephalopathy)
  • Persons affiliated or benefiting from a social security scheme;
  • Having given free, informed, written and signed consent by the patient or his legal representative (no later than the day of inclusion and prior to any review required by the research);

• Eligibility criteria for Acute Transverse Myelitis Patients:

  • Patient of at least 28 days of life
  • Acute onset of symptoms for more than 24 hours
  • Medullary focal abnormality, responsible for motor, sensory or autonomic symptoms
  • contrast enhancement on bone marrow MRI and / or abnormal CSF (≥ 5GB / mm3, protein uptake ≥ 0.40 g / L)
  • Evolution between nadir and maximum symptoms, less than 4 weeks
  • Persons affiliated or benefiting from a social security scheme;
  • Having given free, informed, written and signed consent by the patient or his legal representative (no later than the day of inclusion and prior to any review required by the research);

Exclusion Criteria:

• Primary vasculitis of the central nervous system or a documented specific impairment in an autoimmune condition
• Cerebral thrombophlebitis if not associated with encephalitis
• Meningitis without clinical or paraclinical argument for cerebral parenchymal involvement
• Pyogenic abscess
• Cerebral or spinal abscess
• Tumoral or hematological pathology of the central nervous system
• Toxic or metabolic encephalopathy
• Transverse myelitis with vascular or traumatic origin
• Known chronic infection with HTLV virus

Patients with suspected acute infectious encephalitis and / or myelitis, according to the clinical and paraclinical criteria described in recommendations of the International Encephalitis Consortium in 2013 and the by the Transverse Myelitis Consortium Working Group in 2002