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Japanese Encephalitis Virus (view source)
Revision as of 14:04, 17 August 2012
, 14:04, 17 August 2012no edit summary
[[Category:To Do - Steph]]
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Also Known As: '''''JE — Japanese B Encephalitis — Hydrancephaly — JEV — JE Virus'''''
==Introduction==
Japanese Encephalitis is caused by a '''[[Culicidae|mosquitoe-borne]] [[Flaviviridae|flavivirus]]''' and affects a wide range of species including ruminants, carnivores, birds and humans.
It is best known for causing reproductive failure in sows and central nervous system disease in horses. Pigs are the main amplifying host.
This disease is '''notifiable''' to the World Organisation for Animal Health [http://www.oie.int/ (OIE)]
JE is '''zoonotic''', epidemics having been recorded in Japan, Korea and India during the mosquito season. Although disease is usually mild or subclinical, fatal encephalitis can develop in children.
==Distribution==
JE has a number of '''insect vectors''', mainly '''[[Culicidae|mosquitoes]]'''. Distribution is restricted to '''South-East Asia'''.
'''Birds''', particularly '''herons''', are '''maintenance hosts''' for JEV while '''pigs''' are '''amplifier hosts.'''
==Clinical Signs==
Key reproductive signs include '''abortion in pregnant sows''', stillbirths, male '''infertility''', lack of libido, small litter sizes and '''heat on palpation''' of the testes and scrotum.
'''Neurological''' disease in '''horses''' features trembling, ataxia, incoordination, opisthotonus, hypermetria, aggression and blindness.
Anorexia, inappetance and ill thrift often accompany other signs.
Infection is usually subclinical in other species.
==Diagnosis==
'''Antibody titres''' can be detected serologically by [[Agglutination|haemagglutination inhibition]], '''[[ELISA testing|ELISA]]''', serum neutralisation and other methods. Antibodies can also be detected in foetuses.
'''Viral antigen''' can be demonstrated in '''brain, placenta and foetuses''' by [[FAT|indirect fluorescent staining '''(IFAT)''']] and avidin-biotin staining.
On '''post-mortem '''of piglets from infected dams, '''hydrocephalus, hydrothorax''', subcutaneous oedema and necrotic foci within the organs are common. The meninges and spinal cord may be congested and cerebellar hypomyelinogenesis has been described. <ref> Morimoto, T. (1969) '''Epizootic swine stillbirth caused by Japanese encephalitis virus. '''Proc symposium on factors producing embryonic and fetal abnormalities, death, and abortion in swine. ''US ARS'', 91-73:137-153</ref>
In male infected pigs, large amounts of '''mucoid fluid''' are present within the [[Testes and Epididymis - Anatomy & Physiology |'''tunica vaginalis''']] and the epididymis and tunic are '''fibrosed'''.
==Treatment==
'''No treatment''' is available in animals.
Human recombinant interferon has been used in human cases of JEV.
==Control==
'''Live attenuated vaccines''' are available against JEV. A human vaccine is available and should be given to those at high risk of exposure to infection.
Fly control is valuable but impractical.
{{Learning
|flashcards = [[Japanese Encephalitis Flashcards]]
}}
==References==
<references/>
{{CABI source
|datasheet = [http://www.cabi.org/ahpc/?compid=3&dsid=78461&loadmodule=datasheet&page=2144&site=160 Japanese encephalitis] and [http://www.cabi.org/ahpc/?compid=3&dsid=78462&loadmodule=datasheet&page=2144&site=160 Japanese encephalitis virus]
|date =6 June 2011
}}
<br><br><br>
{{Nick Lyons
|date = July 8, 2012}}
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[[Category:Flaviviridae]]
[[Category:Zoonoses]]
[[Category:Pig Viruses]][[Category:Horse Viruses]]
[[Category:Reproductive Diseases - Pig]][[Category:Neurological Diseases - Horse]]
[[Category:CABI Expert Review]][[Category:CABI AHPC Pages]]
[[Category:Nick Lyons reviewed]]