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==Introduction==

==Introduction==

'''''A. galli''''', '''''A. dissimilis''''' and '''''A. columbae''''' are nematodes that occur in the '''small intestine''' of '''poultry'''.  They can affect the '''reproductive system''' and in heavy infections, cause '''partial or total obstruction''' of the '''duodenum/jejunum'''.  

'''''A. galli''''', '''''A. compar''''', '''''A. dissimilis''''' and '''''A. columbae''''' are nematodes that occur in the '''small intestine''' of '''poultry'''.  They can cause '''haemorrhagic enteritis'''. Heavy infections cause '''partial or total obstruction''' of the '''duodenum/jejunum'''.  

Adult ''A. galli'' are semi-transparent, have three prominent lips in their oral openings and are the '''biggest nematodes found in poultry'''. Females range from 72 to 116 mm in length and their reproductive organ opens in the middle of the body. Their eggs are oval, with smooth shells and measure 73-92 by 45-57 µm and are distinguished from [[Heterakis#Heterakis gallinarum|

Adult ''A. galli'' are semi-transparent, have three prominent lips in their oral openings and are the '''biggest nematodes found in poultry'''. Females range from 72 to 116 mm in length and their reproductive organ opens in the middle of the body. Their eggs are oval, with smooth shells and measure 73-92 by 45-57 µm. Even if the eggs of [[Heterakis#Heterakis gallinarum|

''H. gallinarum'']] eggs  by their slightly smaller and parallel sides <ref name="Soulsby">Soulsby EJL (1982) '''Helminths, arthropods and protozoa of domesticated animals. '''''Helminths, arthropods and protozoa of domesticated animals''., Ed. 7:xi + 809 pp.44; [many fig., 260 x 195 mm]; many ref.</ref>. Males vary from 51 to 76 mm in length and they have pre-anal suckers and two equal spicules of 1-2.4 mm long.  

''H. gallinarum'']] have slightly smaller and parallel sides<ref name="Soulsby">Soulsby EJL (1982) '''Helminths, arthropods and protozoa of domesticated animals. '''''Helminths, arthropods and protozoa of domesticated animals''., Ed. 7:xi + 809 pp.44; [many fig., 260 x 195 mm]; many ref.</ref>, they can almost not be distinguised from ''A. galli'' eggs.. Males vary from 51 to 76 mm in length and they have pre-anal suckers and two equal spicules of 1-2.4 mm long.  

Compared to  ''A. galli,  A. dissimilis'' is slightly bigger and ''A. columbae'' is slightly smaller.

Compared to  ''A. galli,  A. dissimilis'' is slightly bigger and ''A. columbae'' is slightly smaller.

==Signalment==

==Signalment==

The usual host for ''A. galli'' is the '''chicken''', but it can also infect turkeys, geese, guinea fowl and wild birds.  ''A. dissimilis'' can infect turkeys and ''A. columbae'' is found in pigeons.

The usual host for ''A. galli'' and ''A. compar'' is the '''chicken''', but it can also infect turkeys, geese, guinea fowl and wild birds.  ''A. dissimilis'' can infect turkeys and ''A. columbae'' is found in pigeons.

==Clinical Signs==

==Clinical Signs==

Ascarids cause '''anorexia''', '''diarrhoea''', dehydration, stunted growth, '''unthriftiness''', drooping wings, ruffled feathers, weight loss, dullness, '''lethargy''' and '''misshapened and soft thin shelled eggs''' in poultry.

Ascarids cause '''anorexia''', '''diarrhoea''', dehydration, stunted growth, '''unthriftiness''', drooping wings, ruffled feathers, weight loss, reduced feed consumption rates, changes in behaviour, dullness, '''lethargy''' and '''misshapened and soft thin shelled eggs''' in poultry.

Clinical signs are '''more pronounced''' in chickens '''up to 3 months of age''', after which the worm burden normally decreases. Birds will suffer from '''blood loss, reduced blood sugar''' and '''distended ureters with urates'''.

Clinical signs are '''more pronounced''' in chickens '''up to 3 months of age''', after which the worm burden normally decreases but can still be very high.<ref name="Kaufmann">Kaufmann F, Das G, Sohnrey B, Gauly M (2011) '''Helminth infections in laying hens kept in organic free range systems in Germany'''. Livestock Science. 10.1016/j.livsci.2011.05.015. </ref> Birds will suffer from '''blood loss, reduced blood sugar''' and '''distended ureters with urates'''.

==Distribution==

==Distribution==

Infected chickens '''pass''''' A. galli'' eggs in their '''faeces'''. The '''larvae develop inside the egg''' until they reach their '''infective stage (L3)''' within 10-20 days or more, depending on environmental temperature and humidity. The embryonated egg can survive a winter with moderate frost and remain infective in deep litter systems for years depending on the temperature, humidity, pH and ammonium concentration.

Infected chickens '''pass''''' A. galli'' eggs in their '''faeces'''. The '''larvae develop inside the egg''' until they reach their '''infective stage (L3)''' within 10-20 days or more, depending on environmental temperature and humidity. The embryonated egg can survive a winter with moderate frost and remain infective in deep litter systems for years depending on the temperature, humidity, pH and ammonium concentration.

''Ascaridia galli'' has a '''direct lifecycle''' and it is complete when a new host (another chicken) ingests the infective embryonated eggs (L3) from contaminated water or feed. Three layers around the egg protect the larvae until it reaches the duodenum/ jejunum, where they hatch within 24hrs and enter the '''histotropic phase'''. They '''embed themselves into the mucosal layer of the intestine'''. The more eggs are present the longer the histotropic phase lasts. The length of this stage before the final maturation has been reported to be between 3 to 54 days <ref name="Herd and McNaught">Herd RP, McNaught DJ (1975) '''Arrested development and the histotropic phase of Ascaridia galli in the chicken''''' ,International Journal for Parasitology '', 5: 401-406</ref>. The '''prepatent period''' varies from '''5 to 8 weeks'''.

''Ascaridia galli'' has a '''direct lifecycle''' and it is complete when a new host (another chicken) ingests the infective embryonated eggs (L3) from contaminated water or feed. Three layers around the egg protect the larvae until it reaches the duodenum/ jejunum, where they hatch within 24hrs and enter the '''histotropic phase'''. They '''embed themselves into the mucosal layer of the intestine'''. The more eggs are present the longer the histotropic phase may last. The length of this stage before the final maturation has been reported to be between 3 to 54 days <ref name="Herd and McNaught">Herd RP, McNaught DJ (1975) '''Arrested development and the histotropic phase of Ascaridia galli in the chicken''''' ,International Journal for Parasitology '', 5: 401-406</ref>. The '''prepatent period''' varies from '''5 to 8 weeks'''.

Adult ''A. galli'' worms may migrate through the lumina of the large intestine and cloaca and end up in the oviduct, where they can be incorporated into the hen’s egg. Occasionally, earthworms can ingest ''A. galli'' eggs and ascarids are transmitted when the chicken ingests the worm.   

Adult ''A. galli'' worms may migrate through the lumina of the large intestine and cloaca and end up in the oviduct, where they can be incorporated into the hen’s egg. Occasionally, earthworms can ingest ''A. galli'' eggs and ascarids are transmitted when the chicken ingests the worm.   

==Control==

==Control==

In '''free range''' systems, '''young birds''' can be '''isolated''' and put onto '''ground previously unused by poultry'''. '''Rotation''' of poultry '''runs''' is recommended. In houses, '''raised feeding and watering stations''' will reduce the transmission of the pathogen via the faecal oral route.

In '''free range''' systems, '''young birds''' can be '''isolated''' and put onto '''ground previously unused by poultry'''. '''Rotation''' of poultry '''runs''' is recommended. In houses, '''raised feeding and watering stations''' will reduce the transmission of the pathogen via the faecal oral route. The use of genetically based resistance is intensively discussed.<ref name="Gauly">Gauly M, Bauer C, Preisinger R, Erhardt G (2002) '''Genetic differences of Ascaridia galli egg output in laying hens following a single dose infection'''. Vet. Parasitol., 103, 99-107.</ref><ref name="Kaufmann1">Kaufmann F, Daş G; Preisinger R, Schmutz M, König S, Gauly M (2011) '''Genetic resistance to natural helminth infections in two chicken layer lines.''' Vet. Parasitol., 176, 250 – 257.</ref>

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[[Category:Ascaridoidea]]

[[Category:Ascaridoidea]]

[[Category:Avian Nematodes]]

[[Category:Avian Nematodes]]

[[Category:Alimentary Diseases - Birds]]

[[Category:Alimentary Diseases - Birds]]

[[Category:Reproductive Diseases - Birds]]

[[Category:Reproductive Diseases - Birds]]

[[Category:CABI Expert Review]]

[[Category:CABI Expert Review Completed]]