JAPANESE ENCEPHALITIS

JAPANESE ENCEPHALITISMD.KABIUL AKHTER ALI Vector Borne Disease Consultant NVBDCP, NRHMDistrict Heath & Family Welfare Samiti Uttar Dinajpur OverviewEconomic impactHistoryEpidemiologyTransmissionClinical SignsDiagnosis and TreatmentDisease in HumansPrevention and ControlActions to Take/Program mode

2Japanese Encephalitis

FlaviviridaeFlavivirusThe name is derived from the Latin flavus Flavus means yellowRefers to yellow fever virus EnvelopedSingle stranded RNA virusMorphology not well defined

3History1870s: JapanSummer encephalitis epidemics1924: Great epidemic in Japan6,125 human cases; 3,797 deaths1935: Virus first isolatedFrom a fatal human encephalitis case1938: Isolated from Culex tritaeniorhynchus1952: First evidence of J E1955:First case in India1958:First viral isolation in India1973:First outbreak inBankura/Burdwan1978:widespread occurance/monitoring NMEPInitiation of immunisation killed mouse brain vaccine4Economic ImpactAnimalsPorcineHigh mortality in pigletsEquineUp to 5% mortality rateHumansCost for immunization and medical treatment

5Geographic DistributionEndemic in temperate and tropical regions of AsiaReduced prevalence in JapanHas not occurred in U.S.

JapanChinaKoreaIndonesiaIndiaPhilippines6Morbidity/MortalitySwineHigh mortality in pigletsDeath rare in adult pigsEquineMorbidity: 2%, during an outbreakMortality: 5% HumansMortality: 5-40%Serious neurologic sequelae: 45-70%

7TransmissionVector-borne diseaseEnzootic cycleMosquitoes: Culex speciesCulex vishnuii/pseudovishnui/tritinorinchusPaddy fieldsReservoir/Amplifying hostsPigs, batsArdeid (wading) birdsPossibly reptiles and amphibiansIncidental hostsHorses, humans,(dead end)

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9Global ProblemLeading cause of viral encephalitis3 billion live in endemic areas50000 cases reported annually10-15 thousand deaths annuallyINDIA-33o million live in endemic areas in 15 states/ut135 districts are affectedClinical Signs: SwineIncubation period not knownExposure early in pregnancy more harmful Birth of stillborn or mummified fetuses Piglets: Neurological signs, deathBoars: Infertility, swollen testicles

11Post Mortem LesionsHorsesNon-specificNonsuppurative meningoencephalitisSwineFetusesMummified and dark in appearanceHydrocephalusCerebellar hypoplasiaSpinal hypomyelinogenesis

12Differential DiagnosisEquine Other viral encephalitides, Hendra, rabies, neurotoxins, toxic encephalitisSwineMyxovirus-parainfluenza 1, coronavirus, Menangle virus, porcine parvovirus13SamplingBefore collecting or sending any samples, the proper authorities should be contacted

Samples should only be sent under secure conditions and to authorized laboratories to prevent the spread of the disease14DiagnosisClinicalHorses: Fever and CNS disease Swine: High number of stillborn pigletsLaboratory TestsDefinitive: Viral isolationBlood, spinal cord, brain, CSFRise in titerNeutralization, HI, IF, CF, ELISACross reactivity of Flaviviruses15Treatment No effective treatmentSupportive care

16Clinical Signs-HumansIncubation period: 5 to 15 daysMost asymptomatic or mild signsChildren < 15 years and ElderlyAt highest risk for severe diseaseElderly: High case fatality rate (30%)For every case 200-1000 undetected/asymptomatic casesDisease clinical perspective divided into mild/moderate/severe/asymptomatic cases17Clinical Signs: SevereAcute encephalitis Headache, high fever, stiff neck, stuporSevere encephalitisParalysis, seizures, convulsions, coma, and deathNeuropsychiatric sequelae45-70% of survivorsIn utero infection possibleAbortion of fetus18Post Mortem LesionsPan-encephalitisInfected neurons scattered throughout CNSOccasional microscopic necrotic fociThalamus generally severely affected

19Diagnosis and TreatmentClinicalLaboratory TestsTentative diagnosisAntibody titer: HI, IFA, CF, ELISAJE-specific IgM in serum or CSFDefinitive diagnosisVirus isolation: CSF sample, brainNo specific treatmentSupportive care20Public Health SignificanceStrengthening of surveillanceCapacity building for diagnosis/case management to reduce fatalityClinical laboratory support/adequacy of medicines in hospitalsVector surveillance strengtheningFocused IEC for early reportingIncreasing indigenous capacity of vaccine production

21DisinfectionBiosafety Level 3 precautionsChemicalEthanol, glutaraldehyde, formaldehydeSodium hypochlorite (bleach)Iodine, phenols, iodophorsPhysicalDeactivation at 133oF (for 30 minutes)Sensitive to ultraviolet light and gamma radiation22PreventionVector controlEliminate mosquito breeding areasAdult and larvae control( chemical larvicides, Biolarvicides, larvivorous fish)Environmental managementVaccinationEquine and swineHumansPersonal protective measuresAvoid prime mosquito hours/IVMSpace spray-Fogging with pyrethrum/malathionUse of repellants /ITN/curtains23. Prevention(Program mode)Strengthening JE surveillance- identifying /setting of 50 sentinel sites12 Apex Referral laboratories(Diagnosis)Guidelines for AES/JE surveillanceVBD Control Surveillance Unit at BRD Medical College GorakhpurSub office ROHFW Lucknow at GorakhpurNIV Pune unit at BRD Medical College Gorakhpur(funded by GOI/ICMR)VaccinationLive attenuated vaccineUsed in equine and swineSuccessful for reducing incidenceInactivated vaccine (JE-VAX)/SA 14-14-2 Chinese-Single dose IM(Children 1-15 years)Used for human beings2006-11 districts in 4 states(Assam,Karnataka,WB &UP)2007 Expanded to 27 districts in 9 states2008- 23 districts in 9 states coveredLeft out and new cohorts covered in routine immunisation

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