JAPANESE B ENCEPHALITIS.NBR

JAPANESE B ENCEPHALITISby Dr.N.Bayap ReddyAssistant ProfessorCommunity MedicineChennai Medical College hospitalTirupati : 

JAPANESE B ENCEPHALITISby Dr.N.Bayap ReddyAssistant ProfessorCommunity MedicineChennai Medical College hospitalTirupati

EPIDEMIOLOGY : 

EPIDEMIOLOGY

INTRODUCTION : 

INTRODUCTION MOSQUITO BORNE ENCEPHALITIS CAUSED BY GROUP B ARBOVIRUS (FLAVI VIRUS) AND TRANSMITTED BY CULICINE MOSQUITOES ZOONOTIC DISEASE

HISTORY : 

HISTORY 1871 JAPANESE ENCEPHALITIS DESCRIBED IN JAPAN 1934 JAPANESE ENCEPHALITIS VIRUS WAS ISOLATED

WORLD SCENARIO : 

WORLD SCENARIO 50000 CASES OF JE OCCUR GLOBALLY EACH YEAR WITH 10000 DE ATHS AND NEARLY 15000 DISABLED SPORADIC CASES(Occasional cases, widely distributed in time and place): are observed in China, Japan, Taiwan, Korea, Philippines, Indonesia, Malaysia, Singapore, Myanmar, Bangladesh and Eastern areas of Russia. REGIONAL, SEASONAL OUTBREAKS : Occurs in Thailand, parts of India and Srilanka.

INDIAN SCENARIO : 

INDIAN SCENARIO JE first isolated in 1955 at Vellore, Tamil Nadu. Subsequently, the outbreaks have occurred in 25 States / Union Territories of India. JE virus infection is widespread and is particularly very high in Southern States of India viz., Andhra Pradesh (AP) Tamil Nadu and some parts of Karnataka.

NB: Indian authorities have reported 6171 cases nation-wide, including 5700 cases and 1315 deaths in Uttar Pradesh alone : 

NB: Indian authorities have reported 6171 cases nation-wide, including 5700 cases and 1315 deaths in Uttar Pradesh alone INCIDENCE OF JE

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AGENT JE VIRUS FLAVIVIRUS SS-RNA ENVELOPED ICOSAHEDRAL EPIDEMOLOGICAL ASPECTS

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NATURAL CYCLE OF JE VIRUS

ANIMAL RESERVOIRS : 

ANIMAL RESERVOIRS PIGS MAJOR VERTEBRATE HOSTS CONSIDERED AS ‘AMPLIFIERS’ OF VIRUS Pigs not manifest symptoms even though most infected CATTLES/BUFFALOES NOT NATURAL HOSTS OF JE VIRUS ACT AS’MOSQUITC ATTRACTANTS’ BIRDS POND HERONS,CATTLE EGRETS,POULTRY,DUCKS Note :HORSES ARE ONLY ANIMALS WHICH MANIFEST JE VIRUS INFECTION

HOST FACTORS : 

HOST FACTORS AGE: MAJORITY OF CASES ARE CHILDREN LESS THAN 15 YRS (85%) OR OVER 60 YRS(10%) SEX: MALES ARE MORE AFFECTED THAN FEMALES POPULATION MOBILITY MIGRATION OF PEOPLE FROM ENDEMIC AREAS TO OTHER AREAS OCCUPATION MOSTLY A RURAL DISEASE ,CLOSELY RELATED TO AGRICULTURAL PRACTISES

ENVIRONMENTAL FACTORS : 

ENVIRONMENTAL FACTORS SEASON JE IS A SEASONAL DISEASE PREVALENCE IS FROM MAY TO OCTOBER ( RELATED TO AGRICULTURAL PRACTICES) RAINFALL INCREASES THE OPPORTUNITIES FOR BREEDING OF MOSQUITOES

VECTOR OF JE : 

VECTOR OF JE CULICINE MOSQUITOES (C.TRITAENIORHNCHUS,C.VISHNUI, C.GELIDUS) SOME ANOPHELINES C.TRITAENIORHNCHUS HAS BEEN IMPLICATED AS IMPORTANT VECTOR IN SOUTH INDIA

HABITS : 

HABITS BREEDING HABITS BREED IN RICE FIELDS, SHALLOW DITCHES AND POOLS CHOICE OF HOST ZOOPHILIC,FEEDING PRIMARILY ON ANIMAL HOSTS TIME OF BITING USUALLY AT NIGHTS

MODES OF TRANSMISSON : 

MODES OF TRANSMISSON DISEASE IS TRANSMITTED TO MAN BY BITE OF INFECTED MOSQUITOES NO MAN TO MAN TRANSMISSION MAN IS INCIDENTAL “DEAD END” HOST INCUBATION PERIOD IT VARIES FROM 5-15 DAYS

CLINICAL FEATURES,DIAGNOSIS OF JAPANESE ENCEPHALITIS : 

CLINICAL FEATURES,DIAGNOSIS OF JAPANESE ENCEPHALITIS

CLINICAL FEATURES : 

CLINICAL FEATURES Divided into 4 stages: 1. Prodromal stage 2. Sub acute stage 3. Acute Encephalitic stage 4. Late convalescence stage

CLINICAL FEATURES : 

CLINICAL FEATURES Incubation period-5 to 16 days Disease:asymptomatic infection=1:250 to 1:1000 Represents tip of iceberg Disease depends on – severity of infection susceptibility of host Virulence of agent It is characterized by CNS involvement Japanese encephalitis is also called BRAINFEVER

SYMPTOMS AND SIGNS : 

SYMPTOMS AND SIGNS PRODROMAL PHASE:- Duration : 1- 6 days High grade fever, headache malaise photophobia

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ENCEPHALITIC STAGE:- Seizures ,altered sensorium,muscular rigidity, mask like face. Abnormal doll’s eye moments ,absent corneal reflex, pupillary reflex ,deviation of angle of mouth ,loss of consciousness Symptoms and signs of raised ICT -headache, vomiting, hemiplegia,bradycardia,irregular breathing Signs and symptoms of meningeal irritation

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DURING OUTBREAK

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HOSPITILISATION

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LATE STAGE:- Begins when active inflammation is at end i.e.temp. and ESR touch normal Mental impairment Increased deep tendon reflexes Paresis of UMN lesion - LMN lesion type - Speech impairment Death 35-50%-short prodromal stage JE is the disease in children with early mortality Average duration of illness and death is 9 days

DIAGNOSIS : 

DIAGNOSIS Clinical signs and symptoms LAB DIAGNOSIS:- CSF lymphocytic pleocytosis Normal glucose level SEROLOGICAL TESTS:- Detection of IgM antibodies –first week IgM-capture ELISA shows sensitivity 88% -with sera 81% with CSF

DD IN ENDEMICS : 

DD IN ENDEMICS Other viral meningitis:-serological tests -viral culture Tubercular meningitis:-reduced CSF glucose,papilledema Parasitic infections :-toxoplasmosis Active demyelinating disease Bulbar poliomyelitis-history of having not received polio vaccine

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Management of J E Only symptomatic & Supportive treatment maintenance of airway fluid and electrolyte balance control of convulsions, raised ICP,Temperature

Prevention and control of Japanese Encephalitis : 

Prevention and control of Japanese Encephalitis

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Principles of Control : No specific treatment per se. Vector control is the main mode of prevention Control of amplifier hosts Vaccination

VECTOR CONTROL : 

VECTOR CONTROL VECTORS: C.tritaenorhynchus,C.gelidus C.vishnui. Principles of arthropod control: Environmental control Chemical control Biological control Genetic control Newer methods NB :”Integrated approach”

Life history of MOSQUITO : 

Life history of MOSQUITO

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Mosquito control measures 1.Anti larval measures 2.Anti adult measures 3.Personal protection

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ANTI LARVAL MEASURES 1.Environmental control :best approach as results are more permanent. a. Source reduction-elimination of cesspools, ditches b. Intermittent irrigation c. Filling and drainage operation d. Provision of piped water supply e. Proper disposal of refuse.

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2.Chemical control: Commonly used larvicides are a. Mineral oil -diesel oil,kerosene,mosquito larvicidal oil ,etc. MOA :oil spreads and forms thin film which cuts air supply to larvae .appl rate-40to90 L/hectare once a week b.Paris Green -[copper acetoarsenite] Micro crystalline powder insoluble in water. MOA-stomach poison.

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c. Synthetic Insecticides - Organophosphorus cmpds like FENTHION, CHLORPYRIFOS ,ABATE etc. abate-very effective and least toxic.ccn.-1ppm. DDT and HCH not used. Toxicant Dosage[g/ha] Abate 56-112 Fenthion 22-112 Chlorpyrifos 11-16 3.Biological control- Small fish like Gambusia, lebester which feed on larvae can be use in burrow pits, cesspools etc.

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, Gambusia affinis

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ANTI-ADULT MEASURES- 1. Residual sprays -DDT is the insectiside of choice. Dosage 1-2g of pure DDT/sqm applied 1-3 times a year to walls and other surfaces. Malathion ,propoxur- applied where DDT resistance encountered. Toxicant dosage[g/sqm] avg,durationof effectiveness DDT 1-2 6-12 months Malathion 2 3 “ 2. Space sprays- sprayed into the atmosphere in the form of fog or mist using hand guns or power sprays a. Pyrethrum extract- excellant spray from pyrethrum flowers. Active principle-pyrethrin is a nerve poison dose -1oz/1000 cft. b. Residual insecticides- Malathion ,Fenitrothion for ULV fogging

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The pyrethrum flower

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. Space spraying and spray guns

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3. Genetic control- sterile male technique,cytoplasmic incompatability,chromosomal translocation Newer methods -insect growth regulators,chemosterilants etc. PERSONAL PROTECTION [i]Mosquito nets-size of the holes 0.0475” no. of holes/sq inch 150 [ii] Screening of buildings –Cu or Bronze gauze with 16 meshes/inch [iii] Mosquito repellants or culicifuges-used mainly on skin. Ex. Deet all-purpose repellant “INTEGRATED APPROACH”

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.

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Mosquito coils

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VACCINATION Active Immunization -worldwide 3 JE vaccines are present 1.Inactivated mouse brain killed vaccine 2. Primary Hamster kidney, 3.Live attenuated Passive Immunization Ig’s are not available INACTIVATED MOUSE BRAIN KILLED VACCINE Central Research institute ,Kasauli has developed this vaccine VIRAL STRAIN- Nakayama strain of JE virus isolated from spinal fluid of a human case in 1935 and maintained by cont. mouse brain passage DOSAGE AND ROA- 1st-------------2nd--------------3rd-----------booster 7-14 d 1mnth 3yrs Adults >3yrs– 1ml dose s.c.Children[1-3yrs] – 0.5 ml s.c.

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INDICATIONS: a. Endemic areas- in rural areas opf asia where intense JE virus transmission through enzootic life cycle leads to high risk of exposure at an early age. IN such areas UNIVERSAL PRIMARY IMMUNIZATION is indicated for children[1-2 yrs].Also in areas agricultural developed like thailand and Japan In these areas immunity should be maintained upto 10 yrs of age. b. Travelers c. Researchers and LAB workers. CONTRAINDICATIONS :people allergic to rodent derived products. ADVERSE EFFECTS: Swelling ,redness and tenderness in 20% vaccinees Low grade fever and Myalgia in 10- 30% Post vaccination neurologic deficits. EFFICACY : 90-95%

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Vaccination is not recommended as outbreak control measure as it takes 1 month after the 2nd dose to develop antibodies at protective levels and outbreaks are short-lived CONTROL OF PIGS -As pigs are amplifier host, piggeries should be 4-5 km away from human habitat. vaccination of pigs is also important to prevent viremia in pigs. Disposal of garbage and sewage should be done appropriately so that breeding of pigs can be controlled.

LEVELS OF PREVENTION : 

LEVELS OF PREVENTION PRIMARY PREVENTION HEALTH PROMOTION: EFFICIENT CONTROL OF MOSQUITO AND OTHER AMPLIFIER HOSTS LIKE PIGS AND EGRETS. HEALTH EDUCATION SPECIFIC PROTECTION : DEVELOPMENT OF SAFE AND STANDARD VACCINE. PERSONAL PROTECTION MEASURES AGAINST MOSQUITOS

LEVELS OF PREVENTION : 

LEVELS OF PREVENTION SECONDARY PREVENTION EARLY DIAGNOSIS: Its possible through surveillance There are 3 types of surveillance Sero-surveillance in high risk groups, animals and birds. Vector surveillance for vector density and infection Case surveillance A. where no JE transmission is detected but vector is present [acute CNS syndromes, fever clustering.] b. where it is endemic or epidemic

LEVELS OF PREVENTION : 

LEVELS OF PREVENTION TERTIARY PREVENTION Rehabilitation of paralytic patients by physiotherapy. Technical support for surveillance, epidemiological monitoring of the disease, for outbreak investigations and control is provided by state health authorities.

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Inspite of all these methods Control of JE is difficult because- Outdoor habit of the vector Scattered distribution of cases spread over large areas Role of different reservoir hosts Specific vectors for different geographical and ecological areas Immunization status of various population groups is not known making it difficult to delineate vulnerable groups. No specific control programme . [as JE is mosquito one disease JE control is a part of [NATIONAL ANTI-MALARIA CONTROL PROGRAMME]

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THANK YOU