Japanese encephalitis virus: Difference between revisions
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== Background == |
== Background == |
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+ | === Virology === |
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* Single-stranded positive-sense enveloped virus in the family [[Flaviviridae]] and genus [[Flavivirus]] |
* Single-stranded positive-sense enveloped virus in the family [[Flaviviridae]] and genus [[Flavivirus]] |
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− | * Found in Asian and the western Pacific |
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+ | === Epidemiology === |
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− | * Reservoir is pig and wading birds |
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− | * Vector-borne, transmitted by [[Vector::Culex]] mosquitoes |
+ | * Vector-borne, transmitted by [[Vector::Culex]] mosquitoes, mainly [[Vector::Culex tritaeniorhynchus]] |
+ | * Found in Asia and the western Pacific, including India, southeast Asia, and eastern Asia, and as far south as parts of northern Australia |
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+ | * Enzoonotic transmission cycle includes mosquitoes, pigs, and water birds, primarily in rural and periurban areas |
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+ | * Seasonal transmission |
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+ | ** In temperate climates, transmission is more common in the warm season, which can include outbreaks and epidemics |
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+ | ** In tropical and subtropical climates, transmission is year-round, but intensifies during the rainy season and in the pre-harvest season where rice is grown |
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* More common in children and non-immune adults |
* More common in children and non-immune adults |
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* Overall, extremely low risk for travellers with 66 cases in Western travellers since 1973 and estimated less than 1 case per 10 million trips |
* Overall, extremely low risk for travellers with 66 cases in Western travellers since 1973 and estimated less than 1 case per 10 million trips |
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* Incubation period of [[Usual incubation period::5 to 15 days]] |
* Incubation period of [[Usual incubation period::5 to 15 days]] |
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* 99% of infections are asymptomatic |
* 99% of infections are asymptomatic |
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+ | * Mild infections can cause fever and headache, with or without other symptoms |
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+ | * Severe illness has rapid onset high fever, headache, neck stiffness, disorientation, coma, seizures, spastic paralysis, and death |
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=== Prognosis and Complications === |
=== Prognosis and Complications === |
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* 20-30% mortality among people who develop encephalitis |
* 20-30% mortality among people who develop encephalitis |
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− | * 30-50% of survivors have neuropsychiatric symptoms |
+ | * 30-50% of survivors have permanent neuropsychiatric symptoms, including paralysis, seizures, and aphasia |
== Management == |
== Management == |
Latest revision as of 11:18, 13 March 2023
Background
Virology
- Single-stranded positive-sense enveloped virus in the family Flaviviridae and genus Flavivirus
Epidemiology
- Vector-borne, transmitted by Culex mosquitoes, mainly Culex tritaeniorhynchus
- Found in Asia and the western Pacific, including India, southeast Asia, and eastern Asia, and as far south as parts of northern Australia
- Enzoonotic transmission cycle includes mosquitoes, pigs, and water birds, primarily in rural and periurban areas
- Seasonal transmission
- In temperate climates, transmission is more common in the warm season, which can include outbreaks and epidemics
- In tropical and subtropical climates, transmission is year-round, but intensifies during the rainy season and in the pre-harvest season where rice is grown
- More common in children and non-immune adults
- Overall, extremely low risk for travellers with 66 cases in Western travellers since 1973 and estimated less than 1 case per 10 million trips
Clinical Manifestations
- Incubation period of 5 to 15 days
- 99% of infections are asymptomatic
- Mild infections can cause fever and headache, with or without other symptoms
- Severe illness has rapid onset high fever, headache, neck stiffness, disorientation, coma, seizures, spastic paralysis, and death
- May have parkinsonism
Prognosis and Complications
- 20-30% mortality among people who develop encephalitis
- 30-50% of survivors have permanent neuropsychiatric symptoms, including paralysis, seizures, and aphasia
Management
- Supportive
Prevention
- Vaccine is not routinely recommended due to the rarity of disease
- Vaccine may be considered if there will be rural exposure, repeated travel to risk areas, longer cumulative duration of travel (e.g., > 30 days), or travel in areas suffering an outbreak
- However, disease is still rare