Changes

==Introduction==

==Introduction==

Avian Encephalomyelitis (AE) is commonly known as epidemic tremor in chickens.  It is caused by ''Avian encephalomyelitis-like virus 1''(AEV)''' which is a single-stranded RNA''' (ssRNA) virus belonging to the [[Picornaviridae| '''''Picornaviridae''''']] family.  It was formerly classified as an ''enterovirus'' but is now considered a '''''Hepatovirus''''' as its genome ecodes for a single polyprotein (2134 amino acids), which shares greater resemblance to that of the hepatitis A viruses than the other picornavirus genera.  The virus has a non-enveloped capsid with icosahedral symmetry and approximately 26 nm in diameter and a buoyant density of 1.31 g/ml in caesium chloride <ref>Tannock, G.A., Shafren, D.R., (1994) '''''Avian encephalomyelitis: a review'''''. ''Avian Pathology'', 23(4):603-620; 85 ref.</ref>.  There is only one serotype of AEV, which is not related antigenically to other avian picoronaviruses, which is why it has been referred to in the past as an enteroviruses or enterovirus-like viruses.  

Avian Encephalomyelitis (AE) is commonly known as epidemic tremor in chickens.  It is caused by ''Avian encephalomyelitis-like virus 1'' (AEV)''', which is a single-stranded RNA''' (ssRNA) virus belonging to the [[Picornaviridae| '''''Picornaviridae''''']] family.  It was formerly classified as an ''enterovirus'' but is now considered a '''''Hepatovirus''''' as its genome ecodes for a single polyprotein (2134 amino acids), which shares greater resemblance to that of the hepatitis A viruses than the other ''picornavirus'' genera.  The virus has a non-enveloped capsid with icosahedral symmetry and is approximately 26 nm in diameter and has buoyant density of 1.31 g/ml in caesium chloride <ref>Tannock, G.A., Shafren, D.R., (1994) '''''Avian encephalomyelitis: a review'''''. ''Avian Pathology'', 23(4):603-620; 85 ref.</ref>.  There is only one serotype of AEV, which is not related antigenically to other avian ''picoronaviruses'', which is why it has been referred to in the past as an enteroviruses or enterovirus-like viruses.  

Avian Encephalomyelitis (AE)is of economic concern to breeders and layers as it causes a '''decrease in egg production''' in laying hens, a '''decrease in egg hatchability''', '''neurological diseases in chicks under three weeks of age''' and '''affected chicks that that survive are considered unlikely to be profitable'''.

Avian Encephalomyelitis (AE)is of economic concern to breeders and layers as it causes a '''decrease in egg production''' in laying hens, a '''decrease in egg hatchability''', '''neurological diseases in chicks under three weeks of age''' and '''affected chicks that that survive are considered unlikely to be profitable'''.

==Signalment==

==Signalment==

The domestic host for AEV is the '''chicken''' but it can also infect species of '''partridge, turkey, quail, guineafowl and pheasants'''. The infection causes the most serious disease in chicks under 3 weeks of age and older chicks show fewer clinical signs.  Laying hens show a temporary reduction in their  productivity . The incubation period varies from 5 to 14 days depending on the route of infection.

The domestic host for AEV is the '''chicken''' but it can also infect species of '''partridge, turkey, quail, guineafowl and pheasants'''. The infection causes the most serious disease in chicks under 3 weeks of age and older chicks show fewer clinical signs.  Laying hens show a temporary reduction in their  productivity . The incubation period varies from 5 to 14 days depending on the route of infection.  

==Clinical Signs==

==Clinical Signs==

==Epidemiology==

==Epidemiology==

The virus replicates in the epithial cells of the alimentary tract and is circulated in the bloodstream to other organs and the central nervous system (CNS).  The virus is shed within 3 days of oral ingestion and in young chicks can continue to be shed for over two weeks.  Shedding ceases once specific antibody's are produced. The virus can be spread both horizontally (faecal-oral route) and vertically.  

The virus replicates in the epithial cells of the alimentary tract and is circulated in the bloodstream to other organs and the central nervous system (CNS).  The virus is shed within 3 days of oral ingestion and in young chicks can continue to be shed for over two weeks.  Shedding ceases once specific antibody's are produced. The disease is spread '''horizontally''', via the faecal-oral route and chicks from non-immune layers under the age of three weeks are neurologically affected.  '''Vertical transmission''' can also occur from infected layers to their chicks.  The virus may be shed for several weeks. Once a bird becomes infected with the disease or is vaccinated it is immune to AE for life, some birds are left blind.  AE is not considered a zoonosis.

==Diagnosis==

==Diagnosis==