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ENCEPHALITIS: ORIGIN, DIAGNOSIS AND TREATMENT

Debayan Chakraborty*

West Bengal-713301.

E.mail: [email protected]

INTRODUCTION

Encephalitis is a vector borne disease caused by a group of B arbovirus (Flavivirus) and transmitted by culicine mosquitoes, notably C.tritaeniorhynchus, C.vishnui, C.gelidus and along with some anophelines.

It is now well-established that a substantial proportion of encephalitides are associated with auto-antibodies directed against the extracellular domains of cell-surface proteins which are critical in the regulation of neuronal excitability. These include LGI1, CASPR2, contactin-2 (VGKC-complex antibodies), and the NMDA, AMPA, and GABAB receptors.

HISTORY OF ENCEPHALITIS 1800s- recognized in Japan. 1924- Japan epidemic.6125cases,3797deaths 1935- virus isolated in brain Japanese patient who

died of encephalitis 1938- virus isolated from Culex mosquito in japan 1948- Japan outbreak 1949- korea outbreak Today- extreamely prevalent in South East Asia

30,000-50,000 cases reported year 2014.

CAUSES OF ENCEPHALOPATHY Hypoxic/ischaemic Metabolic (liver and renal failure, diabetes) Toxic (alcohol, drugs) Vascular (vasculitis, SLE, SAH, SDH, stroke,

Behcet’s) Epileptic (non-convulsive status) Nutritional deficiency Systemic infections (malaria) Traumatic brain injury Malignant hypertension Mitochondrial cytopathy (Reye’s and MELAS

syndromes) Hashimoto’s encephalopathy Paraneoplastic limbic encephalitis Neuroleptic malignant syndrome…….. (and more!)

PROGNOSIS IN HSE Mortality > 70% if untreated (20% with Rx) Poor prognostic factors

-Age > 60 yrs -GCS < 7 -Delay in starting acyclovir (esp > 2days)

2/3 rds pts have neuropsychiatric sequelae -69% memory impairment -45% personality/behavior change -41% dysphasia -25% epilepsy

CONCLUSION Some cases of encephalitis may be associated with autoantibodies to cell surface proteins. These syndromes have characteristic clinical features and often a good response to immunotherapies. As more antibody assays are developed, the spectrum of immunotherapy-responsive phenotypes will continue to expand.

REFERENCE

WHO-recommended standards for surveillance of selected vaccine-preventable diseases [http://www.who.int/vaccines

documents/DocsPDF06/843.pdf]

Davison KL, Crowcroft NS, Ramsay ME, Brown DW, Andrews NJ:Viral encephalitis in England,

1989–1998:what did we miss?Emerg Infect Dis2003, 9:234:240.