Japanese encephalitis (JE) is a viral disease transmitted by Culex mosquitoes that infects humans and animals. It is a major public health problem in Asia, where an estimated 50,000 cases and 10,000 deaths occur annually. The virus is maintained in a cycle between mosquitoes and amplifying hosts like pigs and wading birds. Mosquitoes become infected by feeding on infected hosts and transmit the virus to humans and horses. The virus enters through the mosquito bite and travels to the brain, where it can cause neurological damage and symptoms ranging from fever and headache to convulsions and coma. Prevention strategies focus on mosquito control through spraying and reducing breeding habitats, as well as vaccines for humans.

1. JAPANESE ENCEPHALITIS

2. INTRODUCTION
• Definition:
JE is an acute arboviral infection of horses,
pigs and humans. It’s a zoonotic disease i.e.
infecting mainly animals and incidentally man.

3. ARBOVIRUSES (ABV)
• Viruses of vertebrates biologically transmitted
by hematophagus insect vectors
• Special characteristic: Ability to multiply in
arthropods

4. AETIOLOGY
• Zoonotic disease
• Family: Flaviviridae

5. JE - GLOBAL SCENARIO
• Major public health disease in Asia
• Virus first isolated in Japan in 1935
• As per WHO estimates 50 thousand serious
cases and 10 thousand deaths each year
• Disease is prevalent in Indian Sub-continent,
Nepal, India, Sri Lanka and some areas in
Bangladesh
5

6. Global scenario contd…,
 Other SE Asian countries reporting cases
include:
• Myanmar, Thailand, Cambodia, China
• Indonesia, Laos, Vietnam, Malaysia,
Philippines, Taiwan,
• Hong Kong and
• Korea

7. POND HERON

8. LIFE CYCLE OF JAPANESE ENCEPHALITIS

9. Mosquito Vectors
• C. tritaeniorhynchus
• C. vishnui
• C. gelidus

10. Culex tritaeniorhynchus
(Cx vishnui group)

11. Breeding Habitat
• Rice fields
• Shallow pools
• Ditches

12. A TYPICAL BREEDING HABITAT FOR MOSQUITOES

13. DYNAMICS OF JE TRANSMISSION
13
Environment
Vector Mosquito
Host - Amplifying Host - Carrier
Victim-Accidental
Full Recovery Death
Recovery with
residual
complications

14. PATHOGENESIS
Virus enters the body through the bite of the insect
vector - mosquitoes
↓
After multiplication in local & regional LN, viremia of
varying duration ensues
↓
Virus is transported to target organ (brain) via blood
↓
Virus proliferate & damage the neuronal tissue,
thereby elicits nervous manifestations

15. JE IN MAN : CLINICAL FEATURES
•Incubation Period - 5 to 15 days
Course of disease- 3 stages
a} Prodromal stage: Fever, headache, GIT disturbances
malaise. Duration- 1 to 6 days.
b} Acute encephalitic stage: Fever, 38 to 40.7°C,
nuchal rigidity, focal CNS signs, convulsion & altered
sensorium progressing to coma
c} Late stage and sequelae: neurological signs

16. Treatment
• No clearly effective antiviral agent exists.
• Therapy for symptomatic Japanese
encephalitis virus (JEV) infection is supportive.
• Patients often require feeding, airway
management and anticonvulsants for seizure
control

17. PREVENTION AND CONTROL
 Vector control reduces transmission
IN AFFECTED VILLAGES:
-Aerial or ground fogging with ultra low volume
insecticides(eg.Malathion,Fenitrothion)
-Indoor residual spray - Spraying should cover vegetation around
houses, breeding sites & animal shelters
IN UNINFECTED VILLAGES:
- Those falling within 2-3 km radius of infected villages should
also receive spraying as a preventive measure
 Use of mosquito nets should be advocated

18. AGRICULTURAL PRACTICES :
- water management practice of Paddy
cultivation-
At least one dry day every week - conserve
water, reduce larval population,increase rice
grain yield
Using neem products as fertilizers will also
reduce the mosquito population

19. Vaccines
▪ Three types of JE vaccine in large scale use are:
1. Mouse brain derive, purified & inactivated
vaccine
2. Cell culture derived inactivated vaccine
3. Cell culture derived, live attenuated vaccine –
SA-14-14-2 strain

20. THANK YOU