1 Japanese encephalitis Cause & prevention Department of Health Hong Kong SAR.
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Transcript of 1 Japanese encephalitis Cause & prevention Department of Health Hong Kong SAR.
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Japanese encephalitis Japanese encephalitis Cause & preventionCause & prevention
Department of HealthDepartment of Health
Hong Kong SARHong Kong SAR
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Japanese Encephalitis (JE)Japanese Encephalitis (JE)• Leading cause of viral encephalitis in Asia• 30-50,000 cases annually• Case-fatality 5% to 35%• Transmitted by bite from mosquito
• Occur all year round
• High risk:– After rainy season
– Migratory bird pattern
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Distribution of Japanese encephalitis in AsiaDistribution of Japanese encephalitis in Asia
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Japanese encephalitis in Hong KongJapanese encephalitis in Hong Kong
• Uncommon, &
• Not endemic in Hong Kong
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Transmission of JE serogroup virusesTransmission of JE serogroup viruses
• Transmitted by rice field breeding mosquitoes, mainly Culex tritaeniorhychus
• mosquitoes infected by feeding on infected pigs and wild birds (amplifying hosts)
• Human as dead end hosts• No person-person or animal-person
transmission
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Symptoms of JE infectionSymptoms of JE infection• Most cases asymptomatic• Incubation 4 to 14 days.• Mild -fever with headache• Severe infection
– quick onset– headache & high fever– neck stiffness, – stupor, disorientation, – coma, tremors, – occasional convulsions (especially in infants) and
spastic (but rarely flaccid) paralysis.
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TreatmentTreatment
• No effective specific treatment available
• Supportive treatment only
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PreventionPrevention
• Personal protective measures and mosquito elimination are the most important
• travellers going to endemic areas may consider vaccination
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Prevention of Mosquito BitesPrevention of Mosquito Bites
•Avoid going to rural area during dusk and dawn when the mosquitoes are most active
•Wear light-coloured, long-sleeved clothing and trousers
•Apply DEET-containing mosquito-repellents over exposed parts of the body and clothes every 4 to 6 hours
•For DEET products used by children, its concentration should be less than 10%
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Prevention of Mosquito BitesPrevention of Mosquito Bites
• Place of accommodation should have air-conditioners or mosquito nets; or
• hang mosquito screens around your bed, use insecticides or coil incenses to repel mosquitoes•Install mosquito nets to doors and windows so that mosquitoes can’t get in
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• Put all used cans and bottles into covered dustbins
• Change water for plants at least once a week, leaving no water in the saucers underneath flower pots
Prevent mosquito breedingPrevent mosquito breeding
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• Keep all drains free from blockage
• Cover tightly all water containers, wells and water storage tanks
• Top up all defective ground surfacers to prevent the accumulation of stagnant water
Prevent mosquito breedingPrevent mosquito breeding
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JE VaccinationJE Vaccination
• Prevent encephalitis from JE virus
• Recommended for use in endemic areas
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Adverse effects of vaccinationAdverse effects of vaccination
• 20% of the vaccinees will have tenderness, redness, swelling over the injection site
• Hypersensitivity reactions:Allergic reactions in 0.6% of Western adults
• Encephalitis & encephalopathy– Rare but severe neurological side effects– ~1 to 2.3 per million vaccinees
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Contraindictions for JE vaccinationContraindictions for JE vaccination
• History of previous severe allergic reaction
• Infant< 1yr of age
• Pregnancy
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Do I need to be vaccinated?Do I need to be vaccinated?
• Current recommendations:– Travellers going to endemic areas in Asia or Western
Pacific and staying over one month (particularly in high risk rural areas)
• Where can I have the vaccination?– Hong Kong Traveller’s Health Service of the Department
of Health– Enquiry: 2150 7235
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See Doctor ImmediatelySee Doctor Immediately•Having been bitten by a mosquito and displaying symptoms of JE afterwards
•Falling ill, especially having a fever within one month after you have returned from abroad
•Tell your doctor where you have been
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Health Information Hotline / Web siteHealth Information Hotline / Web site• Central Health Education Unit, DH
Hotline : 2833 0111Web site : www.cheu.gov.hk
• Travel Health Website, DH (on personal protection against mosquito bites & JE vaccination)Web site : www.info.gov.hk/trhealth/c_HKTHS.htm
• Food & Environmental Hygiene Department (to report mosquito breeding)Hotline : 2868 0000 Web site : www.info.gov.hk/fehd