Japanese B encephalitis

Meningoencephalitis

Terms to understand

• Encephalitis• Encephalopathy• Meningitis• Meningism • Myelitis • Radiculitis

Meningoencephalitis

• Acute inflammation of meninges & brain tissue

• CSF – pleocytosis• Gram stain & culture negative• Changes in MRI brain • Mostly self limiting

Etiology

• Enterovirus; coxsackie, polio, echo• Arbovirus; JEV, WNV, Dengue• Herpes virus; HSV1&2, VZ, EBV, CMV.• Others; mumps, measles, rabies, adenoV.• Bacteria; TB, mycoplasma, rickettsiae• Protozoa; acanthameba, toxoplasma

JEV

JEV

JEV

• Flavivirus• Spread by culex• Single stranded RNAV• 1955 in pondicherry• 2005; 1400 deaths in UP & Bihar

DYNAMICS OF JE TRANSMISSION

EnvironmentVector Mosquito

Host - Amplifying Host - Carrier

Victim-Accidental

Full Recovery

DeathRecovery with residual

complications

Subcutaneous injection

Regional lymph nodes

Extra neural Tissues Connective tissue Striated muscle Pancreas Adrenal Smooth muscle Efferent lymphatics

Thoracic duct

Plasma ViremiaReticuloendothelialcell clearance

Humoral antibody

Olfactory epitheliumVascular endothelium

Neural Parenchyma

Neurons, Glia(?)

CNS antibody

lymphocytes, macrophage

Cellular dysfunction Cellular lysisInflammation

?

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Pathogenesis

• Direct invasion & destruction by virus• Host reaction to viral antigens• Meningeal congestion• Mononuclear infiltration• Neuronal disruption• Neuronophagia, vasculitis• Demyelination [ADEM]

Structures affected

• HSV; temporal lobe• Arbovirus; entire brain• Rabies; basal parts• Varicella; cerebellum

Clinical features• Depends on parenchymal involvement• Preceding mild febrile illness & exantheme• Acute onset of high fever, headache,

irritability,lethargy,nausea,myalgia• Convulsions, stupor, coma• Fluctuating FND, emotional outburst• Ant.horn cell injuryflaccid paralysis [west

nile,entero virus]

DD

• Meningitis of various organisms

Clues in history

• Travel • Vaccination• Rash• Oral ulcers• Parotitis, orchitis• Dogbite• Pets

Clues in examination • Cranial N palsy; HSV, EBV, TB.• Ataxia; VZV, • AFP; polio, enteroV, tick borne.• Rash; VZV, typhus, mycoplasma• Parotitis; mumps,• LN; HIV, EBV, CMV, Rubella.• Dementia; HIV• Hydrophobia; rabies.

Diagnosis • CSF: lymphocytic predominance

Protein: normal, high in HSV Glucose: normal, low in mumps Culture of organism [entero V] Viral antigen by PCR Culture from NPswab, vesicle, feces, urine IgM, IgG titre

PLED in HSV

MRI brain (T2W image): right temporal lobe high signal in a patient with herpes encephalitis

Bilateral asymmetric thalamic hyper intensity

Substantia nigra involvement

Management

• Monitor GCS• ABC• Restrict IVF• Anticovulsants, antipyresis ,• Treat ICT• Moitor; glucose, BUN, elect, ABG, LFT,• Acyclovir

Infant < 1 yr Child 1-4 yrs > 4 years

EYES4 Open Open Open

3 To voice To voice To voice

2 To pain To pain To pain

1 No response No response No response

VERBAL5 Coos, babbles Oriented, speaks,

interacts, socialOriented and Alert

4 Irritable cry, consolable

Confused speech, disoriented, consolable

Disoriented

3 Cries persistently to pain

Inappropriate words, inconsolable

Nonsensical speech

2 Moans to pain Incomprehensible, agitated

Moans, unintelligible

1 No response No response No response

MOTOR6 Normal spontaneous

movementNormal spontaneous movement

Follows commands

5 Withdraws to touch Localizes pain Localizes pain

4 Withdraws to pain Withdraws to pain Withdraws to pain

3 Decorticate flexion Decorticate flexion Decorticate flexion

2 Decerebrate extension Decerebrate extension Decerebrate extension

1 No response No response No response

Bad Prognosis

• <3 yrs• GCS <6 for 4days• Hyponatremia

• 50-60% sequalae

Prevention

• Vaccine for jEV– Inactivated mouse brain Vaccine– Live attenuated SA-14-14-2 vaccine

• Mosquito control• Management of pigs

Thank you