Japanese encephalitis - Revision history

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2025-04-08T01:29:45Z

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← Older revision		Revision as of 01:29, 8 April 2025
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	{{Infobox medical condition ~~(new)~~		{{SI}}
			{{Infobox medical condition
	\| name = Japanese encephalitis		\| name = Japanese encephalitis
	\| ~~synonyms~~ = ~~Japanese B encephalitis~~		\| image = [[File:Japanese_encephalitis_distribution_2022.png\|alt=Map showing the distribution of Japanese encephalitis in 2022]]
	\| ~~image~~ = Japanese encephalitis ~~distribution~~ 2022~~.png~~		\| caption = Distribution of Japanese encephalitis in 2022
	\| caption = ~~The geographic distribution~~ of Japanese encephalitis ~~(dark green)~~		\| field = [[Infectious disease]]
	~~\| pronounce =~~		\| symptoms = [[Fever]], [[headache]], [[vomiting]], [[confusion]], [[seizures]]
	\| field = [[~~Infectious disease (medical speciality)\|~~Infectious disease]]		\| complications = [[Neurological disability]], [[death]]
	\| symptoms = ~~Headache~~, ~~fever~~, vomiting, confusion, [[~~seizure~~]]s		\| onset = 5 to 15 days after exposure
	\| complications =		\| duration = Varies
	\| onset = 5 to 15 days after ~~infection~~		\| causes = [[Japanese encephalitis virus]] spread by [[mosquito]] bites
	\| duration =		\| risks = Living in or traveling to [[rural]] areas in [[Asia]] and [[Western Pacific]]
	~~\| types =~~		\| diagnosis = [[Serology]], [[PCR]]
	\| causes = [[Japanese encephalitis virus]] (spread by ~~mosquitoes)~~		\| prevention = [[Vaccination]], [[mosquito control]]
	\| risks =		\| treatment = Supportive care
	\| diagnosis = ~~Blood or~~ [[~~cerebrospinal fluid~~]] ~~testing~~		\| prognosis = 20-30% mortality rate, 30-50% of survivors have permanent [[neurological]] damage
	~~\| differential =~~		\| frequency = 68,000 cases per year
	\| prevention = [[~~Japanese encephalitis vaccine~~]], ~~avoiding~~ mosquito ~~bites~~		\| deaths = 13,600 to 20,400 per year
	\| treatment = [[Supportive care]]
	~~\| medication =~~
	\| prognosis = ~~Permanent neurological problems occur in up to half~~ of survivors
	\| frequency = 68,000
	\| deaths = 17,~~000~~
	}}		}}
	Japanese encephalitis (JE) virus is the leading cause of [[Japanese Encephalitis Vaccine\|vaccine]]-preventable]] [[encephalitis]] in [[Asia]] and the western Pacific. For most travelers to Asia, the risk for JE is very low but varies based on destination, length of travel, season, and activities.		Japanese encephalitis (JE) virus is the leading cause of [[Japanese Encephalitis Vaccine\|vaccine]]-preventable]] [[encephalitis]] in [[Asia]] and the western Pacific. For most travelers to Asia, the risk for JE is very low but varies based on destination, length of travel, season, and activities. ¬†

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	Most people infected with JE do not have symptoms or have only mild symptoms. However, a small percentage of infected people develop inflammation of the brain (encephalitis), with symptoms including sudden onset of headache, high fever, [[disorientation]], [[coma]], [[tremors]] and [[convulsions]]. About 1 in 4 cases are fatal. To prevent getting sick from JE, use an EPA-registered insect repellent, wear long-sleeved shirts and long pants, and get vaccinated.		Most people infected with JE do not have symptoms or have only mild symptoms. However, a small percentage of infected people develop inflammation of the brain (encephalitis), with symptoms including sudden onset of headache, high fever, [[disorientation]], [[coma]], [[tremors]] and [[convulsions]]. About 1 in 4 cases are fatal. To prevent getting sick from JE, use an EPA-registered insect repellent, wear long-sleeved shirts and long pants, and get vaccinated.

	== Symptoms ==		== Symptoms ==
	Most human infections with Japanese encephalitis (JE) virus are asymptomatic; <1% of people infected develop clinical disease. Acute encephalitis is the most commonly recognized clinical manifestation. Milder forms of disease, such as [[aseptic meningitis]] or undifferentiated febrile illness, can also occur. Illness usually begins with sudden onset of fever, headache, and vomiting. Mental status changes, focal neurologic deficits, generalized weakness, and movement disorders may develop over the next few days.		Most human infections with Japanese encephalitis (JE) virus are asymptomatic; <1% of people infected develop clinical disease. Acute encephalitis is the most commonly recognized clinical manifestation. Milder forms of disease, such as [[aseptic meningitis]] or undifferentiated febrile illness, can also occur. Illness usually begins with sudden onset of fever, headache, and vomiting. Mental status changes, focal neurologic deficits, generalized weakness, and movement disorders may develop over the next few days.

	== Clinical features ==		== Clinical features ==
	The classical description of JE includes a [[Parkinsonian syndrome]] with masklike facies, [[tremor]], cogwheel rigidity, and [[choreoathetoid]] movements. Acute [[flaccid paralysis]], with clinical and pathological features similar to those of [[poliomyelitis]], has also been associated with JE. [[Seizures]] are common, especially among children. The case-fatality ratio is approximately 20%–30%. Among survivors, 30%–50% have significant neurologic, cognitive, or psychiatric sequelae.		The classical description of JE includes a [[Parkinsonian syndrome]] with masklike facies, [[tremor]], cogwheel rigidity, and [[choreoathetoid]] movements. Acute [[flaccid paralysis]], with clinical and pathological features similar to those of [[poliomyelitis]], has also been associated with JE. [[Seizures]] are common, especially among children. The case-fatality ratio is approximately 20%–30%. Among survivors, 30%–50% have significant neurologic, cognitive, or psychiatric sequelae.

	== Lab findings ==		== Lab findings ==
	Clinical laboratory findings might include a moderate [[leukocytosis]], mild [[anemia]], and [[hyponatremia]]. [[Cerebrospinal fluid]] (CSF) typically has a mild to moderate [[pleocytosis]] with a lymphocytic predominance, slightly elevated protein, and normal ratio of CSF to plasma glucose. [[Magnetic resonance imaging]] (MRI) of the brain is better than [[computed tomography]] (CT) for detecting JE virus-associated abnormalities such as changes in the [[thalamus]], basal [[ganglia]], [[midbrain]], [[pons]], and [[medulla]]. Thalamic lesions are the most commonly described abnormality; although these can be highly specific for JE in the appropriate clinical context, they are not a very sensitive marker of JE. EEG abnormalities may include theta and delta coma, burst suppression, [[epileptiform]] activity, and occasionally [[alpha coma]].		Clinical laboratory findings might include a moderate [[leukocytosis]], mild [[anemia]], and [[hyponatremia]]. [[Cerebrospinal fluid]] (CSF) typically has a mild to moderate [[pleocytosis]] with a lymphocytic predominance, slightly elevated protein, and normal ratio of CSF to plasma glucose. [[Magnetic resonance imaging]] (MRI) of the brain is better than [[computed tomography]] (CT) for detecting JE virus-associated abnormalities such as changes in the [[thalamus]], basal [[ganglia]], [[midbrain]], [[pons]], and [[medulla]]. Thalamic lesions are the most commonly described abnormality; although these can be highly specific for JE in the appropriate clinical context, they are not a very sensitive marker of JE. EEG abnormalities may include theta and delta coma, burst suppression, [[epileptiform]] activity, and occasionally [[alpha coma]].
	[[File:Japanese Encephalitis vaccine.jpg\|alt=Japanese Encephalitis vaccine\|thumb\|Japanese Encephalitis vaccine]]		[[File:Japanese Encephalitis vaccine.jpg\|alt=Japanese Encephalitis vaccine\|left\|thumb\|Japanese Encephalitis vaccine]]
	== Antibody testing ==		== Antibody testing ==
	JE virus infections are confirmed most frequently by detection of virus-specific antibody in [[CSF]] or serum. Because humans have low or undetectable levels of [[viremia]] by the time distinctive clinical symptoms are recognized, virus isolation and nucleic acid amplification tests are insensitive and should not be used for ruling out a diagnosis of JE. Click here for more information about diagnostic testing.		JE virus infections are confirmed most frequently by detection of virus-specific antibody in [[CSF]] or serum. Because humans have low or undetectable levels of [[viremia]] by the time distinctive clinical symptoms are recognized, virus isolation and nucleic acid amplification tests are insensitive and should not be used for ruling out a diagnosis of JE. Click here for more information about diagnostic testing.

	== Diagnosis ==		== Diagnosis ==
	Japanese encephalitis (JE) should be considered in a patient with evidence of a neurologic infection (e.g., [[meningitis]], [[encephalitis]], or acute [[flaccid paralysis]]) who has recently traveled to or resided in an endemic country in Asia or the western Pacific.		Japanese encephalitis (JE) should be considered in a patient with evidence of a neurologic infection (e.g., [[meningitis]], [[encephalitis]], or acute [[flaccid paralysis]]) who has recently traveled to or resided in an endemic country in Asia or the western Pacific.

	Laboratory diagnosis of JE is generally accomplished by testing of [[serum]] or [[cerebrospinal fluid]] (CSF) to detect virus-specific [[IgM antibodies]]. JE virus IgM antibodies are usually detectable 3 to 8 days after onset of illness and persist for 30 to 90 days, but longer persistence has been documented. Therefore, positive IgM antibodies occasionally may reflect a past infection or vaccination. Serum collected within 10 days of illness onset may not have detectable IgM, and the test should be repeated on a convalescent sample. For patients with JE virus IgM antibodies, confirmatory neutralizing antibody testing should be performed. In fatal cases, nucleic acid amplification, histopathology with [[immunohistochemistry]], and [[virus culture]] of [[autopsy]] tissues can also be useful.		Laboratory diagnosis of JE is generally accomplished by testing of [[serum]] or [[cerebrospinal fluid]] (CSF) to detect virus-specific [[IgM antibodies]]. JE virus IgM antibodies are usually detectable 3 to 8 days after onset of illness and persist for 30 to 90 days, but longer persistence has been documented. Therefore, positive IgM antibodies occasionally may reflect a past infection or vaccination. Serum collected within 10 days of illness onset may not have detectable IgM, and the test should be repeated on a convalescent sample. For patients with JE virus IgM antibodies, confirmatory neutralizing antibody testing should be performed. In fatal cases, nucleic acid amplification, histopathology with [[immunohistochemistry]], and [[virus culture]] of [[autopsy]] tissues can also be useful.
			Diagnostic testing for JE virus IgM antibodies is commercially-available. Confirmatory testing is only available at CDC and a few specialized reference laboratories.
	Diagnostic testing for JE virus IgM antibodies is commercially-available. Confirmatory testing is only available at CDC and a few specialized reference laboratories.

	== Also see ==		== Also see ==
	* [[Japanese encephalitis vaccine]]		* [[Japanese encephalitis vaccine]]

	{{stub}}		{{stub}}

	== External links ==		== External links ==
	{{Medical resources		{{Medical resources
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	\| ICD10 = {{ICD10\|A\|83\|0\|a\|80}}		\| ICD10 = {{ICD10\|A\|83\|0\|a\|80}}
	\| ICD9 = {{ICD9\|062.0}}		\| ICD9 = {{ICD9\|062.0}}
	\| ICDO =		\| ICDO =
	\| OMIM =		\| OMIM =
	\| MedlinePlus =		\| MedlinePlus =
	\| eMedicineSubj = med		\| eMedicineSubj = med
	\| eMedicineTopic = 3158		\| eMedicineTopic = 3158
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	*UK Department of Health. (2006) Immunisation against Infectious Disease [http://www.dh.gov.uk/assetRoot/04/13/79/19/04137919.pdf Chapter 20: Japanese Encephalitis]		*UK Department of Health. (2006) Immunisation against Infectious Disease [http://www.dh.gov.uk/assetRoot/04/13/79/19/04137919.pdf Chapter 20: Japanese Encephalitis]
	*Japanese encephalitis resource library [http://www.path.org/vaccineresources/japanese-encephalitis.php]		*Japanese encephalitis resource library [http://www.path.org/vaccineresources/japanese-encephalitis.php]
	*CDC [https://www.cdc.gov/mmwr/volumes/66/wr/mm6622a3.htm?s_cid=mm6622a3_e Japanese Encephalitis Surveillance and Immunization — Asia and Western Pacific Regions, 2016], MMWR, June 9, 2017, 66(22);579–583		*CDC [https://www.cdc.gov/mmwr/volumes/66/wr/mm6622a3.htm?s_cid=mm6622a3_e Japanese Encephalitis Surveillance and Immunization ‚Äî Asia and Western Pacific Regions, 2016], MMWR, June 9, 2017, 66(22);579–583
	{{Zoonotic viral diseases}}		{{Zoonotic viral diseases}}
	{{DEFAULTSORT:Japanese Encephalitis}}		{{DEFAULTSORT:Japanese Encephalitis}}

Prab at 21:45, 1 April 2025

2025-04-01T21:45:23Z

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-== Summary ==
+{{Infobox medical condition (new)
-[[File:Japanese Encephalitis.png|alt=Japanese Encephalitis|thumb|Japanese Encephalitis]]Japanese encephalitis (JE) virus is the leading cause of [[Japanese Encephalitis Vaccine|vaccine]]-preventable]] [[encephalitis]] in [[Asia]] and the western Pacific. For most travelers to Asia, the risk for JE is very low but varies based on destination, length of travel, season, and activities.
+| name            = Japanese encephalitis
 <youtube>
@@ Line 58: / Line 80: @@
 *Japanese encephalitis resource library [http://www.path.org/vaccineresources/japanese-encephalitis.php]
 *CDC [https://www.cdc.gov/mmwr/volumes/66/wr/mm6622a3.htm?s_cid=mm6622a3_e Japanese Encephalitis Surveillance and Immunization — Asia and Western Pacific Regions, 2016], MMWR, June 9, 2017, 66(22);579–583
 {{Zoonotic viral diseases}}
 {{DEFAULTSORT:Japanese Encephalitis}}
 [[Category:Swine diseases]]

Prab at 15:10, 12 November 2020

2020-11-12T15:10:09Z

New page

== Summary ==
[[File:Japanese Encephalitis.png|alt=Japanese Encephalitis|thumb|Japanese Encephalitis]]Japanese encephalitis (JE) virus is the leading cause of [[Japanese Encephalitis Vaccine|vaccine]]-preventable]] [[encephalitis]] in [[Asia]] and the western Pacific. For most travelers to Asia, the risk for JE is very low but varies based on destination, length of travel, season, and activities.

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Most people infected with JE do not have symptoms or have only mild symptoms. However, a small percentage of infected people develop inflammation of the brain (encephalitis), with symptoms including sudden onset of headache, high fever, [[disorientation]], [[coma]], [[tremors]] and [[convulsions]]. About 1 in 4 cases are fatal. To prevent getting sick from JE, use an EPA-registered insect repellent, wear long-sleeved shirts and long pants, and get vaccinated.

== Symptoms ==
Most human infections with Japanese encephalitis (JE) virus are asymptomatic; <1% of people infected develop clinical disease. Acute encephalitis is the most commonly recognized clinical manifestation. Milder forms of disease, such as [[aseptic meningitis]] or undifferentiated febrile illness, can also occur. Illness usually begins with sudden onset of fever, headache, and vomiting. Mental status changes, focal neurologic deficits, generalized weakness, and movement disorders may develop over the next few days.

== Clinical features ==
The classical description of JE includes a [[Parkinsonian syndrome]] with masklike facies, [[tremor]], cogwheel rigidity, and [[choreoathetoid]] movements. Acute [[flaccid paralysis]], with clinical and pathological features similar to those of [[poliomyelitis]], has also been associated with JE. [[Seizures]] are common, especially among children. The case-fatality ratio is approximately 20%–30%. Among survivors, 30%–50% have significant neurologic, cognitive, or psychiatric sequelae.

== Lab findings ==
Clinical laboratory findings might include a moderate [[leukocytosis]], mild [[anemia]], and [[hyponatremia]]. [[Cerebrospinal fluid]] (CSF) typically has a mild to moderate [[pleocytosis]] with a lymphocytic predominance, slightly elevated protein, and normal ratio of CSF to plasma glucose. [[Magnetic resonance imaging]] (MRI) of the brain is better than [[computed tomography]] (CT) for detecting JE virus-associated abnormalities such as changes in the [[thalamus]], basal [[ganglia]], [[midbrain]], [[pons]], and [[medulla]]. Thalamic lesions are the most commonly described abnormality; although these can be highly specific for JE in the appropriate clinical context, they are not a very sensitive marker of JE. EEG abnormalities may include theta and delta coma, burst suppression, [[epileptiform]] activity, and occasionally [[alpha coma]].
[[File:Japanese Encephalitis vaccine.jpg|alt=Japanese Encephalitis vaccine|thumb|Japanese Encephalitis vaccine]]
== Antibody testing ==
JE virus infections are confirmed most frequently by detection of virus-specific antibody in [[CSF]] or serum. Because humans have low or undetectable levels of [[viremia]] by the time distinctive clinical symptoms are recognized, virus isolation and nucleic acid amplification tests are insensitive and should not be used for ruling out a diagnosis of JE. Click here for more information about diagnostic testing.

== Diagnosis ==
Japanese encephalitis (JE) should be considered in a patient with evidence of a neurologic infection (e.g., [[meningitis]], [[encephalitis]], or acute [[flaccid paralysis]]) who has recently traveled to or resided in an endemic country in Asia or the western Pacific.

Laboratory diagnosis of JE is generally accomplished by testing of [[serum]] or [[cerebrospinal fluid]] (CSF) to detect virus-specific [[IgM antibodies]]. JE virus IgM antibodies are usually detectable 3 to 8 days after onset of illness and persist for 30 to 90 days, but longer persistence has been documented. Therefore, positive IgM antibodies occasionally may reflect a past infection or vaccination. Serum collected within 10 days of illness onset may not have detectable IgM, and the test should be repeated on a convalescent sample. For patients with JE virus IgM antibodies, confirmatory neutralizing antibody testing should be performed. In fatal cases, nucleic acid amplification, histopathology with [[immunohistochemistry]], and [[virus culture]] of [[autopsy]] tissues can also be useful.

Diagnostic testing for JE virus IgM antibodies is commercially-available. Confirmatory testing is only available at CDC and a few specialized reference laboratories.

== Also see ==
* [[Japanese encephalitis vaccine]]

{{stub}}

== External links ==
{{Medical resources
| DiseasesDB = 7036
| ICD10 = {{ICD10|A|83|0|a|80}}
| ICD9 = {{ICD9|062.0}}
| ICDO =
| OMIM =
| MedlinePlus =
| eMedicineSubj = med
| eMedicineTopic = 3158
| MeshID = D004672
| Orphanet = 79139
}}
{{Portal|Viruses}}
*Centers for Disease Control and Prevention [https://www.cdc.gov/japaneseencephalitis/ Questions and Answers About Japanese Encephalitis]
*Australian government Department of Health and Aging, [http://www.health.gov.au/internet/main/publishing.nsf/Content/cda-surveil-nndss-casedefs-cd_je.htm Japanese Encephalitis], 2012
*UK Department of Health. (2006) Immunisation against Infectious Disease [http://www.dh.gov.uk/assetRoot/04/13/79/19/04137919.pdf Chapter 20: Japanese Encephalitis]
*Japanese encephalitis resource library [http://www.path.org/vaccineresources/japanese-encephalitis.php]
*CDC [https://www.cdc.gov/mmwr/volumes/66/wr/mm6622a3.htm?s_cid=mm6622a3_e Japanese Encephalitis Surveillance and Immunization — Asia and Western Pacific Regions, 2016], MMWR, June 9, 2017, 66(22);579–583
*{{cite book |last1=Simon |first1=LV |last2=Kruse |first2=B |title=Encephalitis, Japanese |date=January 2018 |pmid=29262148 |url=https://www.ncbi.nlm.nih.gov/books/NBK470423/ |publisher=StatPearls Publishing |location=FL}}
{{Zoonotic viral diseases}}

{{Use dmy dates|date=April 2017}}

{{DEFAULTSORT:Japanese Encephalitis}}
[[Category:Swine diseases]]
[[Category:Neglected tropical diseases]]
[[Category:Tropical diseases]]
[[Category:Viral encephalitis]]
[[Category:RTT]]
[[Category:Vaccine-preventable diseases]]