EPIDEMIOLOGY OF JAPANESE ENCEPHALITIS AND CONTROL MEASURES

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EPIDEMIOLOGY OF JAPANESE ENCEPHALITIS AND CONTROL
MEASURES
Dr.I.Selvaraj, I.R.M.S B.SC., M.B.B.S., ( M. D
COMMUNITY MEDICINE )., D.P.H., D.I.H., P.G.C.H
FW (NIHFW, NEW DELHI) Sr.D.M.O (ON STUDY
LEAVE) INDIAN RAILWAY MEDICAL SERVICE
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Seen in picture is a man rushing his child to
a hospital in Ghorakpur, Uttar Pradesh.)
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Doctors look at a child who is being treated for
Japanese Encephalitis at a hospital in Lucknow,
India, Thursday, Sept. 8, 2005. The
death toll from an outbreak of Japanese
Encephalitis in northern India has reached nearly
600, as another 53 people died overnight.
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• Japanese Encephalitis is a viral zoonotic disease
  of Public health importance, because of its
  epidemic potential and high case
  mortality rate. 
• It is a mosquito borne zoonotic disease.  
• The virus infects mainly animals through
  migrating birds.  Pig is the amplifier host. 
  Man is affected incidentally.  
• J.E. is primarily a disease of rural,semi urban,
  agricultural areas where vector mosquitoes
  proliferate in close association
  with pigs and other animal reservoirs. 
• Man to man transmission is not possible. 
• The detection of cases are difficult due to the
  disease apparent and in apparent nature.
• Once the human is infected with the disease it
  leads to death in most of the
  cases. 
• If survive the patient will be with severed
  physical and neurological complications.

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Japanese Encephalitis is a mosquito-borne viral
infection that occurs chiefly in three areas (1)
China and Korea, (2) the Indian sub-continent
consisting of India, parts of Bangladesh,
southern Nepal, and Sri Lanka, and (3) the
southeast Asian countries of Burma, Thailand,
Cambodia, Laos, Vietnam, Malaysia, Indonesia and
the Philippines. Japanese Encephalitis also may
occur with a lower frequency in Japan, Taiwan,
Singapore, Hong Kong, and eastern Russia.
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• The virus was isolated for the first time in the
  world from a post-mortem human brain in Japan in
  1933
• JE was clinically diagnosed for the first time in
  India in 1955 at Vellore, erstwhile North Arcot
  district of Tamil Nadu.
• Approximately 3 billion people and 60 of the
  world's population live in endemic region
• 50,000 cases with 10,000 deaths were notified
  annually from a wide geographic range.
• In India there was a rise of JE incidence in
  1980s and has dropped significantly and
  maintained till 1995
• . The major outbreaks coincided with the heavy
  rainfall and or floods.
• In India, JE is considered mainly as a pediatric
  problem.

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JE OUTBREAK INDIA

• Nagpur (1954-1955)
• North Arcot , Madras (1955)
• Agra,U.P- 1958
• W.Bengal 1973
• TN, KA,WB,AP,Bihar,Assam,U.P-1977-1979
• Goa, Kerala, Haryana (samuel et.al.2000) .
• 1145 cases of Japanese encephalitis have been
  reported from 14 districts of Uttar Pradesh
  Province, India from 29 July to 30 August 2005.
  About one-fourth of these (n296) have died. 90
  cases from the adjoining districts of Bihar have
  also been admitted to the hospitals in Uttar
  Pradesh.

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Children romp in a rice field near Rakshwapar
village in the northern Indian state of Uttar
Pradesh, a bowl-shaped breeding ground for
mosquitos that spread Japanese encephalitis.
This year has been exceptionally rainy, leaving
mosquito-friendly pools of water everywhere. At
least 850 people, mostly children, have already
died from the incurable disease.
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AREA OF HIGH OCCURRENCE IN
INDIA

• The three southern states of Tamil Nadu (TN),
  Andra Pradesh, Karnataka were reporting higher
  incidence.
• JE is emerging as a public health problem in
  Kerala
• In a few villages of Cuddalore district of Tamil
  Nadu, a known JE-endemic area (Chidambaram,
  Virudhachalam, Thittakudi)

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TAMILNADU

• In the early 80s cases were reported from
  Tamilnadu in the following revenue districts
  Tiruvannamalai, Dharmapuri, Namakkal,
  Trichirapalli, Dindigul, Theni,
  Madurai,Virdhunagar, Tirinelveli,  and Tuticorin.
• However for the past 5 years sporadic cases are
  reported from Villupuram, Cuddalore,and
  Perambalur districts only.

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Incidence of Japanese Encephalitis - Tamil Nadu
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• The viruses responsible for these diseases are
  classified as arbovirus and these diseases are
  collectively called as arbovirus encephalitis.
• JEV is related to St. Louis encephalitis virus,
  Murray Valley virus and West Nile virus.
• The virus is antigenically related to several
  other flaviviruses including dengue virus.
• JE virus is a member of the family Flaviviridae.
• I t is a single stranded RNA virus.
• It has three proteins
• A) envelope protein
• B) core protein
• C) membrane protein

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Culex mosquito biting human.
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FEMALECULEX QUINQUEFASCIATUS
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Image Culex mosquito laying eggs.(Photograph by
Richard G. Weber)
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VECTORS

• JEV can be transmitted by mosquitoes in the
  genera Culex
• major vectors for JEV transmission in India
  belong to Culex vishnui subgroup which comprises
  of Cx. pseudovishnui colles.
• Though JEV has been isolated from 16 species of
  mosquitoes, the majority of the isolations are
  from Cx. vishnui complex, which breed extensively
  in rice eco system.
• The disease occurrence coincide with the rainy
  season
• The predominant mosquito species involved in JEV
  transmission breed in rice fields and water
  surfaces.
• The birds (egrets, pond herons, paddy birds)
  which a have role in JEV transmission have close
  link with rice fields and water.
• . Among the vertebrate hosts, though the cattle
  populations do not circulate the virus (dead
  end), they support the mosquito species by
  providing blood meal to them.
• . Establishment of pig forms for economical
  reasons are related to human activities in the
  country side.
• Building reservoirs and canals for agricultural
  purposes may harbor potentials for JEV
  transmission.

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• Cx. tritaeniorhynchus -TN, KA, KL
• Cx. vishnui - TN, KA, WB
• Cx. Pseudovishnui - KA, GOA
• Cx. bitaeniorhynchus - KA, WB
• Cx. epidesmus - WB
• Cx. fuscocephala - TN, KA
• Cx. gelidus - TN, KA
• Cx. quinquefasciatus - KA
• Cx. whitmorei - TN,KA, AP, WB
• An. barbirostris - WB
• An. paeditaeniatus - KA
• An. Subpictus - TN, KA, KL
• Ma. annulifera - KL, ASSAM
• Ma. indiana - KL
• Ma. uniformis - KA, KL

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• Man is an incidental and dead-end host.
• Man-to-man transmission does not occur in nature.
  
• Cattle also act as dead-end host in the
  transmission cycle.
• From Ardeid birds, JE infection is transmitted
  by mosquitoes to pigs/ducklings.
• The pigs/ducklings serve as amplifying hosts
  since thevirus multiplies in them.
• . Man or cattle get infected either from birds or
  pigs/ducklings through mosquito bite.
• . Ardeid birdmosquitoArdeid bird and
  pig/ducklingmosquitopig/duckling cycle exist in
  nature.

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• Transmission is usually seasonal
• In temperate zones of China, Japan, Korea and
  northern areas of Southeast Asia, Japanese
  encephalitis is transmitted during summer and
  early autumn -- May to September.
• In north India and Nepal transmission occurs
  from June to November
• In south India and Sri Lanka epidemics are found
  from September to January.

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• The vast majority of JE infections are in
  apparent
• only 1 in 250 infections results symptomatic
  illness
• Most infected persons develop mild symptoms or no
  symptoms at all.
• Symptoms soon after exposure appear 6-8 days
  after the bite of an infected mosquito.
• The incubation period is about 5-15 days.
• Extrinsic incubation period in vector mosquitoes
  is 9-12 days.
• Approximately 25-30 of cases are fatal, some
  with a fulminate course lasting a few days and
  others run a more protracted course in coma.
• . About 30 of those who survive may have
  sequelae.
• Young children (under 10 years) are more likely
  to die, and if they survive, they are likely to
  have residual neurological disability and
  principal sequelae

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Differential Diagnosis

• Cerebral Malaria
• Meningitis
• Febrile Convulsions
• Reys Syndrome
• Rabies
• Toxic Encephalopathy

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• LABORATORY INVESTIGATION
• Peripheral blood picture shows moderate
  peripheral leucocytosis with neurophilia and mild
  anemia.
• CSF (cerbro spinal fluid) analysis Neutrophils
  may predominate in early CSF samples but a
  lymphocytic pleocytosis is typical.
• CSF protein is moderately elevated in about 50
  of cases.
• Serological tests These are to detect
  antibodies to viral antigens, which include the
  plaque reduction virus neutralization test,
  hemagglutination inhibition, and complement
  fixation. . A significant rise in titer should be
  seen with paired samples from the acute and
  convalescent stages.
• The virus is isolated from CSF by inoculating
  into 2-4 day old mice and the virus is identified
  by haemagglutination inhibition. Japanese
  encephalitis virus may also be identified by
  infection of cell cultures (chicken embryo or
  hamster kidney cells, or the mosquito cell line
  C3/36) and by IFA.

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DIAGNOSTIC FACILITIES TAMILNADU

• Sera  are collected from the J.E. cases and sent
  to Virology department, Madurai Medical college
  (or) King Institute, Guindy, Chennai (or)
  Institute of Vector Control and Zoonoses, Hosur
  for Laboratory  diagnosis of J.E. case.
• Vector mosquitoes collected from the field are
  sent to CRME, Madurai and Institute of Vector
  control and Zoonoses, Hosur for PCR analysis for
  detection of virus.

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JE CASE CLASSIFICATION, NICD, NEW DELHI

• SUSPECT A CASE THAT IS COMPATIBLE WITH THE
  CLINICAL DESCRIPTION
• PROBABLE A SUSPECT CASE WITH PRESUMPTIVE
  LABORATORY RESULTS
• CONFIRMED A SUSPECTED CASE THAT IS LABORATORY
  CONFIRMED

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JE CONTROL STRATEGY

• Early Case Detection and Treatment
• Vector Control
• A)REDUCTION OF BREEDING SOURCE FOR LARVAE
  B) REDUCTION IN MAN-MOSQUITO CONTACTC) CONTROL
  OF ADULT MOSQUITOES
• . Prevention
• A) JE VACCINATION

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Reduction of Breeding Source for Larvae

• They are water management system with
  intermittent irrigation system
• incorporation of neem products in rice fields
• The water management is nothing but a strategy of
  alternate drying and wetting water management
  system in the rice fields.
• This can be implemented only with the
  co-ordination of the farmers.
• Introduction of composite fish culture for
  mosquito control in rice fields have been
  evaluated and proved to be successful.

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• PIG CONTROL
• segregation
• slaughtering,
• and vaccination
• MOSQUITO CONTROL
• spraying,
• draining mosquito habitats,
• or using bednets

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• JE VACCINE
• INACTIVATED MOUSE BRAIN VACCINE
• It is expensive vaccine, complicated dosing
  schedule, side effect of this vaccine.
• Inactivated Mouse brain vaccine
• 3-5 US dollars/dose
• 9 15 US dollars/per child
• The mouse brain vaccine manufactured by killing
  populations of mice was being manufactured by
  Central Research Institute, Kasauli.
• LIVE ATTENUATED VACCINE
• SA 14 - 14-2 (Chinese live attenuated vaccine at
  affordable cost, safe, effective).
• This vaccine was developed in China and has been
  used there since 1988.
• it has been licensed and used in South Korea and
  Nepal and licensed in Sri Lanka.
• It also appears feasible that a single dose of
  vaccine will provide life-long protection.

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OTHER NEW VACCINE

• A live, attenuated chimeric vaccine which uses
  a yellow fever vaccine virus strain as its
  backbone (ChimeriVax-JE, manufactured by
  Acambis).
• Clinical trials also are underway for a JE
  vaccine candidate manufactured by Intercell.
  Following a successful Phase II study in the
  United States, Intercell initiated Phase III
  trials in September 2005 to test the vaccines
  safety and immunogenicity in nearly 5,000 adult
  subjects throughout the United States, Europe,
  and other countries. This vaccine is inactivated
  but does not require mouse brains for production.

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RESEARCH PROJECT TAMILNADU In collaboration with
the public health department, the CRME, Madurai
is undertaking the impregnated curtains trials at
Sirimangalam and Nallur Primary Health Centres in
Cuddalaore district for control of J.E. vectors.
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REFERENCE

• http//www.path.org/projects/JE_in_depth.php
• http//www.pon.nic.in/vcrc/jemanag.html
• K.PARK
• LECTURE NOTES ON MALARIA CONTROL AND OTHER VECTOR
  BORNE DISEASES, HOSUR
• MANSONS TROPICAL DISEASES
• JAPANESE ENCEPHALITIS GLOBALLY AND IN
  INDIA-INDIAN JOURNAL OF PUBLIC HEALTH
  VOL.XXXXVIII No.2APRIL-JUNE 2004
• Japanese encephalitis in India An
  overviewKabilan Lalitha, Rajendran R,
  Arunachalam N, Ramesh S, Srinivasan S, Philip
  Samuel P, Dash APCentre for Research in Medical
  Entomology, Madurai, India
• Year 2004    Volume 71    Issue 7 
    Page 609-615