Japanese encephalitis
Japanese encephalitis | |
---|---|
Other names | Japanese B encephalitis |
Supportive care[1] | |
Prognosis | Permanent neurological problems occur in up to half of survivors[2] |
Frequency | 68,000[2] |
Deaths | 17,000[2] |
Japanese encephalitis (JE) is an infection of the brain caused by the Japanese encephalitis virus (JEV).[3] While most infections result in little or no symptoms, occasional inflammation of the brain occurs.[3] In these cases, symptoms may include headache, vomiting, fever, confusion and seizures.[1] This occurs about 5 to 15 days after infection.[1]
JEV is generally spread by
Prevention is generally achieved with the
The disease primarily occurs in
Signs and symptoms
The Japanese encephalitis virus (JEV) has an incubation period of 2 to 26 days.[5] The vast majority of infections are asymptomatic: only 1 in 250 infections develop into encephalitis.[6]
Severe rigors may mark the onset of this disease in humans. Fever, headache and
Increased
In a
Although the net effect of the proinflammatory mediators is to kill infectious organisms and infected cells as well as to stimulate the production of molecules that amplify the mounting response to damage, it is also evident that in a nonregenerating organ such as the brain, a dysregulated innate immune response would be deleterious. In JE the tight regulation of microglial activation appears to be disturbed, resulting in an autotoxic loop of microglial activation that possibly leads to bystander neuronal damage.[8] In animals, key signs include infertility and abortion in pigs, neurological disease in horses, and systemic signs including fever, lethargy and anorexia.[9]
Cause
It is a disease caused by the
Virology
Japanese encephalitis virus | |
---|---|
Flavivirus structure and genome | |
Virus classification | |
(unranked): | Virus |
Realm: | Riboviria |
Kingdom: | Orthornavirae |
Phylum: | Kitrinoviricota |
Class: | Flasuviricetes |
Order: | Amarillovirales |
Family: | Flaviviridae |
Genus: | Flavivirus |
Species: | Japanese encephalitis virus
|
JEV is a virus from the family
Based on the envelope gene, there are five genotypes (I–V). The Muar strain, isolated from a patient in Malaya in 1952, is the prototype strain of genotype V. Genotype V is the earliest recognized ancestral strain.[14] The first clinical reports date from 1870, but the virus appears to have evolved in the mid-16th century. Over sixty complete genomes of this virus had been sequenced by 2010.[citation needed]
Diagnosis
Japanese encephalitis is diagnosed by commercially available tests detecting JE virus-specific IgM antibodies in serum and/or cerebrospinal fluid, for example by IgM capture ELISA.[15]
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.[16] Confirmatory testing in the US is available only at the CDC and a few specialized reference laboratories. In fatal cases, nucleic acid amplification and virus culture of autopsy tissues can be useful. Viral antigen can be shown in tissues by indirect fluorescent antibody staining.[9]
Prevention
Infection with Japanese encephalitis confers lifelong
A
The most common adverse effects are redness and pain at the injection site. Uncommonly, an
The neutralizing antibody persists in the circulation for at least two to three years, and perhaps longer.[21][22] The total duration of protection is unknown, but because there is no firm evidence for protection beyond three years, boosters are recommended every three years for people who remain at risk.[23] Furthermore, there are no data available regarding the interchangeability of other JE vaccines and IXIARO.[citation needed]
Treatment
There is no specific treatment for Japanese encephalitis and treatment is supportive,
A breakthrough in the field of Japanese encephalitis therapeutics is the identification of
The effectiveness of
Epidemiology
Japanese encephalitis (JE) is the leading cause of viral encephalitis in Asia, with up to 70,000 cases reported annually.[29] Case-fatality rates range from 0.3% to 60% and depend on the population and age. Rare outbreaks in U.S. territories in the Western Pacific have also occurred. Residents of rural areas in endemic locations are at highest risk; Japanese encephalitis does not usually occur in urban areas.[citation needed]
Countries which have had major epidemics in the past, but which have controlled the disease primarily by vaccination, include China, South Korea, Singapore, Japan, Taiwan and Thailand. Other countries that still have periodic epidemics include Vietnam, Cambodia, Myanmar, India, Nepal, and Malaysia. Japanese encephalitis has been reported in the Torres Strait Islands, and two fatal cases were reported in mainland northern Australia in 1998. There were reported cases in Kachin State, Myanmar in 2013. There were 116 deaths reported in Odisha's Malkangiri district of India in 2016.[citation needed]
In 2022, the notable increase in distribution of the virus in Australia due to climate change became a concern to health officials as the population has limited immunity to the disease and the presence of large numbers of farmed and feral pigs could act as reservoirs for the virus.[7] In February 2022, Japanese encephalitis was detected and confirmed in piggeries in Victoria, Queensland and New South Wales. On 4 March, cases were detected in South Australia. By October 2022, the outbreak in eastern mainland Australia had caused 42 symptomatic human cases of the disease, resulting in seven deaths.[30][31]
Humans, cattle, and horses are dead-end hosts as the disease manifests as fatal encephalitis. Pigs act as an amplifying host and have a very important role in the epidemiology of the disease. Infection in swine is asymptomatic, except in pregnant sows, when abortion and fetal abnormalities are common sequelae. The most important vector is Culex tritaeniorhynchus, which feeds on cattle in preference to humans. The natural hosts of the Japanese encephalitis virus are birds, not humans, and many believe the virus will therefore never be eliminated.[32] In November 2011, the Japanese encephalitis virus was reported in Culex bitaeniorhynchus in South Korea.[33]
Recently, whole genome
A number of drugs have been investigated to either reduce viral replication or provide neuroprotection in cell lines or studies upon mice. None are currently advocated in treating human patients.
- The use of has been shown to be effective in a mouse model of Japanese encephalitis.
- ubiquitin-proteasome system.[38]
- Minocycline in mice resulted in marked decreases in the levels of several markers, viral titer, and the level of proinflammatory mediators[39] and also prevented blood–brain barrier damage.[40]
Evolution
It is theorized that the virus may have originated from an ancestral virus in the mid-1500s in the Malay Archipelago region and evolved there into five different genotypes which spread across Asia.[41] The mean evolutionary rate has been estimated to be 4.35×10−4 (range: 3.49×10−4 to 5.30×10−4) nucleotide substitutions per site per year.[41]
References
- ^ a b c d e f g "Symptoms and Treatment". CDC. August 2015. Archived from the original on 17 June 2017. Retrieved 29 October 2017.
- ^ a b c d e f g h i j k l m n o p q "Japanese encephalitis". World Health Organization. December 2015. Archived from the original on 13 July 2017. Retrieved 29 October 2017.
- ^ a b "Japanese Encephalitis". CDC. August 2015. Archived from the original on 24 May 2017. Retrieved 29 October 2017.
- ^ "Japanese encephalitis - Causes". 6 February 2019.
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- ^ a b Davey, Melissa (8 March 2022). "What is Japanese encephalitis and why is it spreading in Australia?". The Guardian Australia. Retrieved 20 October 2022.
- S2CID 13192982.
- ^ a b Japanese Encephalitis Virus Archived 18 July 2013 at the Wayback Machine reviewed and published by WikiVet, accessed 11 October 2011.
- ^ PMID 16943399.
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- ^ "Jeev an inactivated Japanese Encephalitis vaccine launched in Hyderabad". pharmabiz.com. 15 September 2012. Archived from the original on 23 October 2012. Retrieved 11 January 2013.
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- ^ EMEA Approval of Vaccine
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- ^ Japanese encephalitis~treatment at eMedicine
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- ^ PMID 28967695.
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- ^ Australian Government Department of National pest & disease outbreaks (March 2022). "Japanese encephalitis".
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(help) - ^ "Japanese encephalitis virus". Australian Government Department of Health and Aged Care. Retrieved 20 October 2022.
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External links
- "Questions and Answers About Japanese Encephalitis". Centers for Disease Control and Prevention. 8 February 2019.
- "Japanese Encephalitis". Australian government Department of Health and Aging. 2012.
- Ramsay, Mary, ed. (2020). "20. Japanese encephalitis". Immunisation against infectious disease. Green Book. Public Health England.
- "Japanese encephalitis resource library".
- Heffelfinger JD, Li X, Batmunkh N, Grabovac V, Diorditsa S, Liyanage JB, Pattamadilok S, Bahl S, Vannice KS, Hyde TB, Chu SY, Fox KK, Hills SL, Marfin AA (9 June 2017). "Japanese Encephalitis Surveillance and Immunization — Asia and Western Pacific Regions, 2016". MMWR Morb Mortal Wkly Rep. 66 (22): 579–583. PMID 28594790. Erratum in: MMWR Morb Mortal Wkly Rep. 2017 Jun 23;66(24):653.
- Simon, LV; Kruse, B (January 2018). "Japanese Encephalitis". Encephalitis, Japanese. FL: StatPearls Publishing. PMID 29262148. NBK470423.