Japanese encephalitis is a mosquito-borne viral disease that affects humans and animals. It is caused by the Japanese encephalitis virus and transmitted by Culex mosquitoes. The virus is maintained in an enzootic cycle between mosquitoes and amplifying hosts like pigs and wading birds. Humans and horses are incidental dead-end hosts. Most human infections are asymptomatic, but severe cases can cause encephalitis with high mortality and neurological sequelae. Diagnosis involves virus isolation from CSF or serum antibody detection. There is no treatment other than supportive care. Prevention strategies include vector control, vaccination of pigs and humans, and personal protective measures. In India, the government conducts JE surveillance, diagnosis,

1. MD.KABIUL AKHTER ALI
Vector Borne Disease Consultant
NVBDCP, NRHM
District Heath & Family Welfare Samiti
Uttar Dinajpur

2. Overview
Economic impact
History
Epidemiology
Transmission
Clinical Signs
Diagnosis and Treatment
Disease in Humans
Prevention and Control
Actions to Take/Program mode

3. Japanese Encephalitis
Flaviviridae
Flavivirus
The name is derived from
the Latin ‘flavus’
Flavus means “yellow”
 Refers to yellow fever virus
Enveloped
Single stranded RNA virus
Morphology not well defined

4. History
 1870s: Japan
 “Summer encephalitis” epidemics
1924: Great epidemic in Japan
 6,125 human cases; 3,797 deaths
1935: Virus first isolated
 From a fatal human encephalitis case
1938: Isolated from Culex tritaeniorhynchus
1952: First evidence of J E
1955:First case in India
1958:First viral isolation in India
1973:First outbreak inBankura/Burdwan
1978:widespread occurance/monitoring NMEP
Initiation of immunisation –killed mouse brain vaccine

5. Economic Impact
Animals
Porcine
 High mortality in piglets
Equine
 Up to 5% mortality rate
Humans
 Cost for immunization and medical treatment

6. Geographic Distribution
Endemic in temperate and
tropical regions of Asia
Reduced prevalence in Korea Japan
Japan China
Has not occurred in U.S. India Philippine
s
Indonesia

7. Morbidity/Mortality
Swine
High mortality in piglets
Death rare in adult pigs
Equine
Morbidity: 2%, during an outbreak
Mortality: 5%
Humans
Mortality: 5-40%
Serious neurologic sequelae: 45-70%

8. Transmission
Vector-borne disease
Enzootic cycle
Mosquitoes: Culex species
 Culex vishnuii/pseudovishnui/tritinorinchus
 Paddy fields
Reservoir/Amplifying hosts
 Pigs, bats
 Ardeid (wading) birds
 Possibly reptiles and amphibians
Incidental hosts
 Horses, humans,(dead end)

10. Global Problem
Leading cause of viral encephalitis
3 billion live in endemic areas
50000 cases reported annually
10-15 thousand deaths annually
INDIA-33o million live in endemic areas in 15
states/ut
135 districts are affected

11. Clinical Signs: Swine
Incubation period not known
Exposure early in pregnancy more harmful
Birth of stillborn or mummified fetuses
Piglets: Neurological signs, death
Boars: Infertility, swollen testicles

12. Post Mortem Lesions
Horses
Non-specific
Nonsuppurative
meningoencephalitis
Swine
Fetuses
 Mummified and dark in appearance
 Hydrocephalus
 Cerebellar hypoplasia
 Spinal hypomyelinogenesis

13. Differential Diagnosis
Equine
 Other viral encephalitides, Hendra, rabies,
neurotoxins, toxic encephalitis
Swine
Myxovirus-parainfluenza 1, coronavirus, Menangle
virus, porcine parvovirus

14. Sampling
Before 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 disease

15. Diagnosis
Clinical
Horses: Fever and CNS disease
Swine: High number of stillborn piglets
Laboratory Tests
Definitive: Viral isolation
 Blood, spinal cord, brain, CSF
Rise in titer
 Neutralization, HI, IF, CF, ELISA
 Cross reactivity of Flaviviruses

16. Treatment
No effective treatment
Supportive care

17. Clinical Signs-Humans
Incubation period: 5 to 15 days
Most asymptomatic or mild signs
Children < 15 years and Elderly
At highest risk for severe disease
 Elderly: High case fatality rate (30%)
 For every case 200-1000 undetected/asymptomatic cases
 Disease clinical perspective divided into
mild/moderate/severe/asymptomatic cases

18. Clinical Signs: Severe
Acute encephalitis
Headache, high fever, stiff neck, stupor
Severe encephalitis
Paralysis, seizures, convulsions, coma, and death
Neuropsychiatric sequelae
45-70% of survivors
In utero infection possible
Abortion of fetus

19. Post Mortem Lesions
Pan-encephalitis
Infected neurons scattered
throughout CNS
Occasional microscopic
necrotic foci
Thalamus generally severely
affected

20. Diagnosis and Treatment
Clinical
Laboratory Tests
Tentative diagnosis
 Antibody titer: HI, IFA, CF, ELISA
 JE-specific IgM in serum or CSF
Definitive diagnosis
 Virus isolation: CSF sample, brain
No specific treatment
Supportive care

21. Public Health Significance
Strengthening of surveillance
Capacity building for diagnosis/case management to
reduce fatality
Clinical laboratory support/adequacy of medicines in
hospitals
Vector surveillance strengthening
Focused IEC for early reporting
Increasing indigenous capacity of vaccine production

22. Disinfection
Biosafety Level 3 precautions
Chemical
Ethanol, glutaraldehyde, formaldehyde
Sodium hypochlorite (bleach)
Iodine, phenols, iodophors
Physical
Deactivation at 133oF (for 30 minutes)
Sensitive to ultraviolet light and gamma radiation

23. Prevention
Vector control
 Eliminate mosquito breeding areas
 Adult and larvae control( chemical larvicides, Biolarvicides,
larvivorous fish)
 Environmental management
Vaccination
 Equine and swine
 Humans
Personal protective measures
 Avoid prime mosquito hours/IVM
 Space spray-Fogging with pyrethrum/malathion
 Use of repellants /ITN/curtains

24. Prevention(Program mode)
Strengthening JE surveillance- identifying /setting of
50 sentinel sites
12 Apex Referral laboratories(Diagnosis)
Guidelines for AES/JE surveillance
VBD Control Surveillance Unit at BRD Medical
College Gorakhpur
Sub office ROHFW Lucknow at Gorakhpur
NIV Pune unit at BRD Medical College
Gorakhpur(funded by GOI/ICMR)

25. Vaccination
Live attenuated vaccine
Used in equine and swine
Successful for reducing incidence
Inactivated vaccine (JE-VAX)/SA 14-14-2 Chinese-
Single dose IM(Children 1-15 years)
 Used for human beings
 2006-11 districts in 4 states(Assam,Karnataka,WB &UP)
 2007 – Expanded to 27 districts in 9 states
 2008- 23 districts in 9 states covered
 Left out and new cohorts covered in routine immunisation

26. THANK YOU