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[[Category:To Do - CABI]]
Also Known As – '''''Baby Chick Nephritis (BCN) – Infectious Stunting Syndrome (ISS)'''''
Caused By – Avian Nephritis Virus (ANV)
==Introduction==
Avian nephritis is caused by an '''RNA astrovirus''' and affects '''solely chickens.'''
This disease is '''notifiable''' to the World Organisation for Animal Health [http://www.oie.int/ (OIE)]
==Distribution==
Japan, Europe, USA and New Zealand.
The principle method of disease transmission is via '''faeces'''. AN is also transmitted '''vertically''' to eggs and chicks from infected hens.
==Signalment==
The chicken is the only significant host for ANV. Turkeys appear to neither develop disease nor specific antibodies against ANV.
Most infections even in young chicks are '''mild or sub-clinical''', but '''nephrosis and death''' can result in susceptible and immunosuppressed chicks.
Only chicks '''less than 2 weeks old''' usually exhibit clinical signs.
==Clinical Signs==
As the first cells to be infected are enterocytes, '''[[Diarrhoea|diarrhoea]]''' is a common first feature of AN. It may be accompanied by polyphagia, emaciation and sudden deaths particularly in young chickens.
'''Growth retardation''' can be severe and variable and may be accompanied by poor feather development.
'''Dermatological signs''' of disease include erythema of the skin, ruffling of the feathers and vent soiling along with oedema and hindlimb swellings.
Disease is more severe when combined with '''other immunosuppressive agents''' such as [[Infectious Bursal Disease]] and also with cold stress and poor nutrition.
In cases of '''baby chick nephropathy''', incidence peaks at ~5 days of age, and mortality rates may rise to 6%. This condition is thought to occur at a low level in most broiler flocks and is merely exacerbated by many factors.<ref>Jones, B. A. H (1992) '''Avian nephritis virus'''. Publication - ''Veterinary Continuing Education, Massey University'', No. 147:53-58; [Proceedings Solvay chicken health course, Massey University, 1992]; 12</ref>
==Diagnosis==
Definitive diagnosis requires demonstration of the virus, usually in kidney tissues.
'''Smears of kidney tissue''' can be fixed onto slides and '''Immunofluorescence or immunohistochemistry''' can be used to demonstrate viral antigens.
Faeces and liver can also be used for viral isolation. Viral presence can be confirmed by immunofluorescence or neutralisation.
Serological tests comprise of '''virus neutralisation, [[ELISA testing|ELISA]] and indirect immunofluorescence''', of which neutralisation is the most sensitive and can be used from one week after initial infection. Antibodies to ANV are however often an incidental finding.
On '''post-mortem''', nephrosis and widespread '''urate deposits''' are often present in young birds. Kidneys have a '''pale cortex and general pale yellowish discolouration. Gouty nodules and tubular casts''' have been observed in some cases. Granulocyte infiltration is often seen with tubule degeneration on histological analysis. Nuclei of affected tubular cells are often swollen or fragmented due to viral propagation. General signs of '''enteritis''' are often present grossly, microscopically and histologically but are non-specific.
In cases of '''Infectious Shunting Syndrome (ISS)''', lesions appear in the '''crypts of lieberkuhn''' featuring '''degenerate macrophages''' accumulating in the lamina propria and cystic crypts in the jejunum. Mineralisation and fibrosis may result in advanced chronic cases of ISS.
==Treatment==
There is no effective treatment for birds infected with AN.
==Control==
Maternal antibodies are usually protective so immunisation of breeding hens is potentially possible but no vaccine is available despite experimental success. This is due to the economic impact of AN being unknown and therefore investment seeming unjustified.
An '''all-in-all-out policy''', thorough emptying of sheds between batches and formaldehyde disinfection have all been demonstrated to reduce incidence of AN and ISS.<ref>Reece, R,, Frazier, J (1991). '''Infectious stunting syndrome breakthrough'''. Poultry International, Nov:16-24.</ref>
Reducing exposure to cold weather, dehydration, transport, overcrowding and other diseases which may be immunosuppressive are also key to prevention of AN.
{{Learning
|flashcards = [[Avian Nephritis Flashcards]]
}}
==References==
<references/>
Animal Health & Production Compendium, '''Avian Nephritis Virus datasheet''', accessed 20/06/2011 @ http://www.cabi.org/ahpc/
Animal Health & Production Compendium, '''Avian Nephritis datasheet''', accessed 20/06/2011 @ http://www.cabi.org/ahpc/
[[Category:To Do - CABI review]]