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%
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
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
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
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