2. INTRODUCTION
Japanese encephalitis (JE)is the most important cause of viral
encephalitis in Asia. Recent literature maintains that there are
nearly 68,000 clinical cases of JE occur each year,with up to
20,400 deaths globally. (Bulletin of WHO ,October 2011). And
again among survivors 20-30% suffer with permanent intellectual,
behavioural, or neurological problems such as paralysis,
recurrent seizures or the inability to speak. The disease is
predominantly found in rural and peri-urban areas, where people
live in closely with vertebrates.
5. *CAUSATIVE AGENT
-It is caused by a group of B arbovirus(flavi virus).
-The virus causing Japanese encephalitis is transmitted
to man by mosquitoes belonging to the culex
ritaeniorhynchus and culex vishnui groups, which breed
particularly in flooded rice fields.
-These culicines are normally zoophilic ,ie,they prefer to
take blood meals from animals.
6. *HOST
-All ages and both sexes are affected.
-The most affected group is children below the age of 15
years.
-Pigs are amplifying hosts: the virus reproduces in pigs
and infects mosquitoes while taking blood meals, but
does not cause disease.
7. -The natural maintenance reservoir: birds of the family
Ardeidae(herons and egrets).Although they do not
demonstrate clinical disease, they do generate high
viraemias up on infection.
-Humans are considered a dead -end host.
8. *ENVIRONMENT
- prilmarily the JE virus transmission occurs in rural agricultural
areas ,often associated with rice production and flooding irrigation.
- In some areas of Asia,this conditions can occur near urban centers.
-In temperate areas of Asia, JE virus transmission shows seasonal
trend. Human disease usually peaks in the summer and fall.
-In the subtropics and tropics ,transmission can occur constantly,
often with a peak during the rainy season.
9. TRANSMISSION
JE virus is transmitted to humans through the bite of
infected culex species mosquitoes, particularly culex
triaeniorhynchus.
11. CLINICAL FEATURES
-The prodromal period may last for many days and is
characterized by fever, headache, nausea, diarrhea,
vomiting and myalgia.
-Mental status may be altered ranging from mild
confusion to overt coma. Seizures are common among
infected especially in children.
-headache and meningismus are found among adults.
12. -Tremor or other involuntary movements may be present.
- A syndrome of Acute Flaccid Paralysis (AFP).
- Fever disappear by the second week, and
choreoathetosis or extrapyramidal symptoms may
develop.
13. LABORATORY DIAGNOSIS
Serum or cerebrospinal fluid (CSF) is tested to find
specific IgM antibodies of JE virus. IgM antibodies are
usually detectable 3-8 days after onset of illness and
continuous for 30-90 days.
14. 1. DETECTION OF ANTIBODIES FROM SERUM
Antibodies are detected from serum by
Hemagluttination Inhibition Test(HIT), Complement
Fixation Test (CFT),Neutralization Test(NT) and
immune diffusion.
15. 2. DETECTION OF ANTIGEN FROM CSF
Antigen detection tests are;
-Immuno Fluorescent Assay (IFA)
- Reverse Passive Haemagglutination Test (RPHA).
16. PREVENTION AND CONTROL
Early diagnosis is based on recognizing the clinical
symptoms and referring the patient to hospital. Community
should be educated about this.
People can suspect JE and seek hospital care based on:
●Fever, loss of consciousness or altered behaviour for 1 hour
to 4 days.
●Symptoms like abnormal movements and posture,squint, fits
and paralysis.
17. While shifting the patient to hospital:
● Maintain calm,quiet, dark environment.
● Do not fiddle the patient much.
● Facilitate clearance of secretions nose and mouth by
turning the head to one side.
18. VACCINATION
Inactivated JE vaccine - JENVAC
The Vero cell - derived purified inactivated JE vaccine JENVAC was
introduced by India in October, 2013. Earlier the vaccine was
imported from China.
Mass vaccination compaigns JENVAC can be administered
as a single dose during epidemics.
As a part of the National Immunization Programme in endemic
regions - JENVAC is given in 2 doses as a routine immunization .
19. ●Inactivated, Vero cell derived, alum - adjuvanted vaccine (SA
14 - 14-2 strain).Primary immunization consists of two
intramuscular doses, 4 weeks apart, booster is recommended
after 1year. First dose at 9 months is recommended by IAP.
●Inactivated Vero cell-derived vaccines (Beijing-1 strain).
Primary immunization, three doses at a days 0,7 and 28 or
two doses given preferably 4 weeks apart (0.25 mL for
children <3years, 0.5 mL for all other ages).First booster is
given at 12-14 months after primary immunization and after
that every 3 years.
20. SURVEILLANCE
The component of JE surveillance consists of three major areas;
•Clinical surveillance through early diagnosis and management
of JE patients at primary health centers.
•Vector surveillance in risk areas of JE to assess the vector
behaviour and strengthen the system accordingly.
•Sero- surveillance to monitor JE specific antibodies in sentinel
animals or birds as well to recognize high risk areas.
21. VECTOR CONTROL INTERVENTION STRATEGIES
■ Alternate wet and dry irrigation (AWDI)
As recognized ,flooded rice fields have been the ideal
breeding place for several mosquito species including those
that transmit JE. The alternate wetting and drying of paddy
fields, helps in interfering with the development of the
mosquito from larvae and pupae to adult which in turn helps
as a technique to control the mosquito of JE.
22. BIOLOGICAL CONTROL STRATEGIES
Natural fishes like Gambusia affinis, Tilapia spp,
Poeciliareticulata or cyprinidae, killfish, nematodes and
crustaceans are used in biological control.
CHEMICAL CONTROL
Deltamethrin,organophosphates and carbamates are used
to control vectors.
23. HEALTH EDUCATION
■Educate community on cause,spread, prevention and
management of JE.
■Involve community members to keep the surroundings clean.
■Engage community in the activities like filling pools ,draining
of accumulated water weekly,lowering water levels in rice
fields etc that would cut down the mosquito breeding places.
24. PERSONAL PROTECTIVE MEASURES
●Wear full sleeved clothes.
●Use of mosquito coils.
burn neem leaves around the house.
●Avoid water stagnation.
26. MANAGEMENT
●There is no specific treatment available. Most often
hospitalized patients are managed with feeding ,airway
management, and anticonvulsants for seizure control.
●in rare cases ,relapses occur months after the recovery.
These patient's may require long term care and
rehabilitation.
●In case of increased intracranial pressure manitol is used.
27. CONCLUSION
Japanese encephalitis is a disease with high mortality
and leaves behind a cripping disability. It can be
prevented by the effective use of vaccine as well by
vector control and environmental modification.
