1. Introduction Japanese encephalitis virus (JEV) is a mosquito borne encephalitis caused by group B arbovirus (flavivirus) and transmitted by Culex mosquitoes. It is a zoonotic disease,i.e. infecting mainly animals and incidentally man. JE is the leading cause of viral encephalitis in asia and occurs in almost all Asian countries. Largely as a result of immunization, its incidence has been declining in japan, the Korean peninsula and in some regions of china, but the disease is increasingly reported from Bangladesh, India, Nepal, Pakistan, northern Thailand and Viet Nam. World Encephalitis Day is celebrated on 22nd February every year by raising awareness about encephalitis. 2. Magnitude of problem JE is the leading cause of viral encephalitis in Asia and occurs in almost all Asian countries. Increasing no of cases are reported from Bangladesh, India, Nepal, Pakistan ,Thailand and Vietnam. Estimated 50,000 case occur globally each year, with 10,000 deaths and nearly 15,000 disabled. About 85% cases are children of less than 15 years of age.  More than 3 billion people are at risk of developing the disease. 3. Global Scenario Major epidemics were reported from Japan (1871 and 1924), northern Vietnam (1965), Thailand (1969, 1970), India (1973), Nepal (1978) and from Sri Lanka (1985-87). At present, the geographic range of JEV infection extends from eastern to Southeast Asia and northern Australia, and to southern Asia. However, it is likely to increase in Bangladesh, Cambodia, Indonesia, Laos, Myanmar, North Korea, Pakistan, Philippines and other countries because of population growth, intensified rice farming, pig rearing, and the lack of vaccination programs and surveillance. 4. Risk Factors Common risk factors in the development of Japanese encephalitis are: Residents or military in Southeast Asia and Western Pacific regions Summer season Outdoor recreational activities Accommodations in endemic areas that lack air conditioning, bed nets, or window screens Contact with: Mosquitos, Birds , Pigs 5. Agent Factor JEV is transmitted to humans through bites from infected mosquitoes of the Culex species (mainly Culex tritaeniorhynchus). The virus exists in a transmission cycle between mosquitoes, pigs and/or water birds (enzootic cycle). 6. Host factor Pigs and aquatic birds (mainly herons and egrets of the Ardeidae family) are the natural hosts for the virus. Pigs are considered amplifying hosts since they allow manifold virus multiplication without suffering from disease and maintain prolonged viraemia . In endemic areas, most people are infected below the age of 15 years. In hyper – endemic areas, half of all Japanese encephalitis cases occur before the age of four years, and almost all before 10 years of age. 7. Mode of Transmission JE virus is transmitted to humans through the bite of infected Culex species mosquitoes, particularly Culex tritaeniorhynchus. The virus is maintained in a cycle between mosquitoes and vertebrate hosts.

1. Japanese Encephalitis
Presented by : Shreya Yadav
Sandip kumar Sah
Srijana Belbase
B.Sc.MLT(3rd Sem) , Nobel College

2. CONTENT
 Introduction
 History
 Magnitude of problem
 Current scenario
 Risk factors
 Epidemiological situation in nepal
 Agent, Host, Environment
 Mode of transmission
 Signs and Symptoms

3.  Clinical features
 Diagnosis
 Treatment
 Preventions and Controls
 Vaccination
 Policy of Government of Nepal

5. INTRODUCTION
Japanese encephalitis virus (JEV) is a mosquito borne
encephalitis caused by group B arbovirus (flavivirus) and
transmitted by Culex mosquitoes.
It is a zoonotic disease,i.e. infecting mainly animals and
incidentally man.
JE is the leading cause of viral encephalitis in asia and occurs in
almost all Asian countries. Largely as a result of immunization, its
incidence has been declining in japan, the Korean peninsula and in
some regions of china, but the disease is increasingly reported
from Bangladesh, India, Nepal, Pakistan, northern Thailand and
Viet Nam.
World Encephalitis Day is celebrated on 22nd February every
year by raising awareness about encephalitis.

6. HISTORY
Genetic studies, suggest that JEV originated from an ancestral
virus in the area of malay of Archipelago.
Clinical recognition dates back to 19th century - 1st clinical case in
1871, at Japan.
1924, a severe epidemic was reported from japan.
1934, Hyashi reproduced the disease in monkey by intra-cerebral
inoculation.
1935, JE virus was isolated from human brain in Tokyo, japan, and
its virological and serological Prototype, Nakayama strain, was
established.

7. Magnitude of problem
JE is the leading cause of viral encephalitis in Asia and occurs in
almost all Asian countries.
Increasing no of cases are reported from Bangladesh, India,
Nepal, Pakistan ,Thailand and Vietnam.
Estimated 50,000 case occur globally each year, with 10,000
deaths and nearly 15,000 disabled.
About 85% cases are children of less than 15 years of age.
More than 3 billion people are at risk of developing the disease.

8. Global Scenario
Major epidemics were reported from Japan (1871 and 1924),
northern Vietnam (1965), Thailand (1969, 1970), India (1973),
Nepal (1978) and from Sri Lanka (1985-87).
At present, the geographic range of JEV infection extends from
eastern to Southeast Asia and northern Australia, and to southern
Asia.
However, it is likely to increase in Bangladesh, Cambodia,
Indonesia, Laos, Myanmar, North Korea, Pakistan, Philippines and
other countries because of population growth, intensified rice
farming, pig rearing, and the lack of vaccination programs and
surveillance.

10. Nepal Scenario
• As a concentrated Japanese encephalitis (JE) control measure,
phase-wise mass vaccination campaigns were started in 2006 and
were completed in 31 high-risk districts by 2011.
• JE vaccine was introduced in phase-wise manner in the routine
immunization of these 31 districts by 2012. After these measures
were taken, JE burden reduced significantly in Nepal.
• However, over the years, as identified by surveillance, JE was
reported from other districts of Nepal as well. Following mass
vaccination campaign in the remaining districts in 2016, JE vaccine
was introduced in the routine immunization of all remaining 44
districts in July 2016.
• As shown in Figure, JE burden in Nepal has reduced significantly
in 2019 compared to the initial years when surveillance was
started.

12. • It shows that 65 districts have reported AES cases in FY
2076/2077. Out of these 65 districts, five districts (Kaski, Siraha,
Saptari, Sunsari, Sankhuwasaba) have reported higher number of
AES cases (between 51-100), and three districts (Morang, Sunsari,
Kathmandu) have reported the highest (> 100).
• In total, 917 AES cases were reported. Among the total reported
AES cases, only 65 (7.08%) were laboratory confirmed for JE.
• This is a major reduction compared to the years before JE
vaccination was started when around 50% of the AES cases were
positive for JE. The majority of laboratory confirmed JE cases (21
out of 65; 32.30%) were reported from Province-1.

15. Risk Factors
Common risk factors in the development of Japanese encephalitis
are:
Residents or military in Southeast Asia and Western Pacific
regions
Summer season
Outdoor recreational activities
Accommodations in endemic areas that lack air conditioning, bed
nets, or window screens
Contact with: Mosquitos, Birds , Pigs

16. Epidemiological situation in Nepal
Appear in Nepal in the late 1970s. The first clinical diagnosis of
JEV infection was done in 1978 . Since then, JE has been endemic
in Terai region of Nepal.
Terai is a tropical, low land plains of Nepal bordering India which is
experiencing larger outbreaks in every 2-5 years.
A total 26,667 cases and 5,381 deaths occurred from JE in Nepal
within the 25 year period (from 1978 to 2003) with 20.2% average
case fatality rate.
Though it is mainly a disease of children, JE has been confirmed in
all age groups in Nepal and higher cases reported in males than in
females. JE has a typical seasonal pattern of outbreak in Nepal.

17. Agent Factor
JEV is transmitted to humans through bites from infected
mosquitoes of the Culex species (mainly Culex tritaeniorhynchus).
The virus exists in a transmission cycle between mosquitoes, pigs
and/or water birds (enzootic cycle).

18. Host factor
Pigs and aquatic birds (mainly herons and egrets of the Ardeidae
family) are the natural hosts for the virus.
Pigs are considered amplifying hosts since they allow manifold
virus multiplication without suffering from disease and maintain
prolonged viraemia .
In endemic areas, most people are infected below the age of 15
years.
 In hyper – endemic areas, half of all Japanese encephalitis cases
occur before the age of four years, and almost all before 10 years
of age.

19. Environmental factors
Environmental factors related to transmission of JE are related
principally to temperature and humidity conditions conducive to
breeding and survival of the vector.
 In tropical and subtropical areas, transmission intensifies in the
rainy season. In temperate locations, transmission usually starts in
April and may last until October.
Habitats supporting the transmission cycle of JE virus are
principally in rural, agricultural locations.
 In many Asian countries, major outbreaks of JE occur at intervals
of 2 - 15 years.

20. Mode of Transmission
JE virus is transmitted to humans through the bite of
infected Culex species mosquitoes, particularly Culex
tritaeniorhynchus.
The virus is maintained in a cycle between mosquitoes
and vertebrate hosts, primarily pigs and wading birds.
 Humans are incidental or dead-end hosts, because they usually
do not develop high enough concentrations of JE virus in their
bloodstreams to infect feeding mosquitoes.
JE virus transmission occurs primarily in rural agricultural areas. In
temperate areas of Asia, JE virus transmission is seasonal. Human
disease usually peaks in the summer and fall. In the subtropics
and tropics, transmission can occur year-round, often with a peak
during the rainy season.

22. Signs and Symptoms
Most JEV infections are mild (fever and headache). In children,
gastrointestinal pain and vomiting may be the dominant initial
symptoms.
Severe disease is characterized by rapid onset of high fever,
headache, neck stiffness, disorientation, coma, seizures, spastic
paralysis and ultimately death.
The case-fatality rate can be as high as 30% among those with
disease symptoms. Of those who survive, 20%–30% suffer
permanent intellectual, behavioural or neurological sequelae such
as paralysis, recurrent seizures or the inability to speak.

24. Clinical feature
Incubation period of Japanese encephalitis ranges from 5 to 15
days.
The illness has three stages:-
a) Prodromal stage: with fever, headache, vomiting, and other
nonspecific symptoms.
b) Acute encephalitic stage: with convulsions, coma, and signs of
raised intracranial tension.
c) Later Stage: Persistence of signs of CNS injury such as Mental
impairment, Increased deep Tendon reflexes, Paralysis either of
the upper or lower motor neuron type, Speech impairment,
Epilepsy, Abnormal movements, Behavior abnormalities.

26. Diagnosis
 A laboratory test is required in order to confirm JEV infection and to
rule out other causes of encephalitis.
Specimen: Virus could be isolated from brain tissue, blood, or
cerebrospinal fluid (CSF) of humans.
Microscopic observation: To confirm JE, microscopic observation
can be implemented through use of JEV specific monoclonal
antibodies for detection via immunofluorescence or
immunohistochemistry.

27. Reverse-transcription polymerase chain reaction (RT-
PCR) can detect JE viral RNA in clinical samples or
cell culture fluid using primers based on conserved
sequences specific to JEV.
The WHO manual for laboratory diagnosis of JEV
recommends testing for JEV-specific IgM antibody in a
single sample of cerebrospinal fluid (CSF) or serum,
using an IgM-capture ELISA is the gold standard for
detection.

28. Treatment
No specific treatments have been found to benefit patients with JE,
but hospitalization for supportive care and close observation is
generally required.
Mostly Less than 1% of people infected with Japanese encephalitis
(JE) virus develop clinical illness.
Treatment is symptomatic. Rest, fluids (hydrated), and use of pain
relievers and medication to reduce fever (Paracetamol) may
relieve some symptoms.

29. Prevention and Control
Japanese encephalitis virus is spread to people through the bite of
an infected mosquito. Mosquitoes bite during the day and night.
The best way to prevent Japanese encephalitis virus infection is to
protect from mosquito bites.
Use insect repellent, wear long-sleeved shirts and pants, treat
clothing and gear, using mosquito nets, and get vaccinated before
traveling.
 Permethrin-treated mosquito nets provide more protection than
untreated nets.
Safe and effective JE vaccines are available to prevent disease.

30. Even if the number of JE-confirmed cases is low, vaccination
should be considered where there is a suitable environment for JE
virus transmission.
Thus, vaccination of humans should be prioritized over vaccination
of pigs and mosquito control measures.
WHO recommends having strong JE prevention and control
activities, including JE immunization in all regions where the
disease is a recognized public health priority, along with
strengthening surveillance and reporting mechanisms.

31. There are 4 main types of JE vaccines currently in use: inactivated
mouse brain-derived vaccines, inactivated Vero cell-derived
vaccines, live attenuated vaccines, and live recombinant (chimeric)
vaccines.
To reduce the risk for JE, all travellers to Japanese encephalitis-
endemic areas should take precautions to avoid mosquito bites.
 Personal protective measures and mosquito elimination are the
most important.

32. Vaccination
Mass JE vaccination campaigns are first conducted in endemic
districts where, all children in the age group of 1 to 15 years will be
vaccinated
Later, JE vaccination is introduced into the routine immunization
schedule of that district
2 doses, 0.5 ml, subcutaneously…
1st dose along with measles vaccine at 9 months of age
2nd dose along with the booster dose of measles at 18-24 months
of age.

33. • Inactivated Vero cell culture-derived Japanese encephalitis (JE)
vaccine (manufactured as IXIARO) is the only JE vaccine licensed
and available in the United States. This vaccine was approved in
March 2009 for use in people aged 17 years and older and in May
2013 for use in children 2 months through 16 years of age.
• Other JE vaccines are
manufactured and used in
other countries but are not licensed
for use in the United States.

37. Goal of Government
The goal of the Programme is to reduce morbidity, mortality and
disability in children due to JE/AES.
To achieve Japanese Enchephalitis Elimination.

38. Objective
(i) to strengthen and expand JE vaccination in affected districts
(ii) to strengthen surveillance, vector control, case management and
timely referral of serious and complicated cases
(iii) to increase access to safe drinking water and proper sanitation
facilities to the target population in affected rural and urban
areas
(iv) to estimate disability burden due to JE/AES, and to provide for
adequate facilities for physical, medical, neurological and social
rehabilitation
(v) to improve nutritional status of children at risk of JE/AES

39. Policy of Government of Nepal
Through surveillance and immunization, Nepal has made
remarkable progress against JE in the past few decades.
However, JE continues to spread to additional districts in Nepal—
including those in the hills and mountains, which may prove more
difficult to reach. The Nepal Ministry of health is continuing to
improve its JE prevention and control program in the following
ways:
1. Expanding JE vaccination to additional districts
 In 2015, Nepal applied for funding from Gavi to expand its JE
vaccination program to 47 of the 75 districts in Nepal.

40.  These campaigns began in May 2016 with the aim of vaccinating
an additional four million children in 44 districts in Nepal and
intensifying coverage in three Terai districts with existing routine JE
immunization.
 Eventually, the country plans to expand JE into the routine
immunization program nationwide.
2. Balancing JE vaccines with other new vaccines
 In addition to adding JE vaccine to its EPI schedule in 2006, Nepal
also added pentavalent vaccine in 2009, inactivated polio vaccine
in 2014, and pneumococcal conjugate vaccine in 2015.

41.  Through careful planning and evidence-based decision making,
Nepal continues to coordinate JE vaccination alongside an
everexpanding list of other lifesaving vaccines and maximize
protection of its children.
3. Ensuring continued safety of JE vaccines
 The WHO position paper on JE vaccines states that CD-JEV has
an acceptable safety profile and studies evaluating CD-JEV in
Nepal found the vaccine to be safe.

42.  To ensure continued safety, Nepal’s EPI has plans to intensify and
strengthen safety surveillance in all districts with JE vaccination
through the central and district immunization safety committees.
4. Improving JE awareness through education
 Education about JE and the availability of vaccines helps increase
community demand for JE vaccines, which can improve
vaccination coverage.
 A 2012 survey of pig farmers in Nepal found that, although they
are at high risk for JE, only 42 percent of the farmers had heard of
JE, and none were vaccinated against it.

43.  By continuing to improve JE awareness through education, the
Nepal MOH aims to increase the reach and sustainability of JE
vaccination to all those at risk.
5. Identification of epidemic prone areas
 And preparedness by early recognition and identification of JE in
peripheral health services; early diagnosis and timely management
of the disease, anti-vector measures (fogging/ULV spraying) in
epidemic foci; developing the necessary nursing care in hospitals.

44. 6. Japanese Encephalitis Control
 Programs such as behavioral change communications (BCC),
surveillance, supply of necessary drugs, diagnosis and treatment,
disease infection risks minimization, mapping of risk-prone areas
and the people, and strengthening of the drugs procurement
system will be launched.

45. PATH’s role in Nepal’s JE program
 Funded by the Bill & Melinda Gates Foundation, PATH’s work to
combat JE provided technical assistance to Nepal, from strategy
development through program implementation and evaluation. In
addition, PATH helped negotiate the low, public-sector price for
CD-JEV, which allowed Nepal to purchase the vaccine for its JE
immunization program.

47. REFERENCES
• https://www.who.int/news-room/fact-sheets/detail/japanese-
encephalitis
• https://www.cdc.gov/japaneseencephalitis/symptoms/index.html
• https://medgag.com/book/parks-textbook-preventive-social-
medicine-25th-edition/
• http://dohs.gov.np/annual-report-2076-77-2019-20/