Ascaridia Galli (Roundworm Large) ...

Ascaridia Galli (Roundworm Large) Heavy Infection in Laying Hens

Ascaridia Galli (Roundworm Large)  Heavy Infection in Laying Hens

These worms are common in poultry, even cage layers, were worms eggs are mechanically carried by flies. Hens 3 months of age or older manifest considerable resistance to infection with A. galli, regardless of previous infection status.

 Most of the times Ascaridia galli infection is a subclinical condition

Pathogenicity is generally low, although in heavy infection. Ascaridia galli infection causes weight depression in the host proportionate to increasing worm burden. In severe infections, an intestinal blockage can occur. Chicken infected with a large number of ascarids suffer retarded growth and increased mortality. 

The damage to the intestinal mucosa results in limiting the absorption of carotene and other micronutrients.

Ascaridia galli can also synergize the effects of other diseases conditions, such as coccidiosis and infectious bronchitis. A. galli reportedly contains and transmit avian reovirus. The infection by this nematode is the occasional finding of this parasite in the hen's egg. Infected eggs can be detected by candling. This nuisance has been greatly reduced by the use of modern anthelminthics to effectively kill both larvae and adult worms.

Observed Clinical Signs Happenings


  • Low mortality or increases gradually

Dead birds

  • Skinny body  (Poor body fleshing condition)

Body Parts (Neck, wings, breast, abdomen, shanks, legs, hocks, feet, joints, vent, and skin, abnormalities), skinny body, retarded growth, weight depression

  • Retarded growth
  • Weight depression
  • Most of Ascaridia galli infection is a subclinical condition

Internal Egg contents defects

  • Yolk colour variable
  • The worm inside the egg detected by candling, although this is most difficult with brown-shelled eggs.

Ascaridia Galli (Roundworm Large) Heavy Infection in Laying Hens DOES NOT exhibit or manifest any of the following clinical signs happenings:

  • Egg drop
  • High mortality or increases rapidly
  • Dead birds: Good body fleshing condition
  • Visibly sick birds
  • Flock behaviour activity change
  • Droppings abnormalities
  • Respiratory abnormalities
  • Neurological Nervous
  • Lameness or unusual movements, incoordination, ataxia
  • Eyes abnormalities
  • Head, Comb, Wattles, Face, Nostrils, Sinuses, Mount, Beak, Ear lobes, abnormalities (except eyes)
  • Feathers abnormalities
  • Feed Consumption Changes
  • Diet or Feed Changes, Recent formulation /diet, Another feed brand
  • Shell quality defects



Causing Agents
Parasitic intestinal track infection of nematode. Worm parasites. Ascaridia galli.
Affected Systems/Organs
Reproductive system. Intestinal tract.
Fecal-oral Cycle. The parasites may be transported by grasshoppers and earthworms and are resistant to environmental. A. galli reportedly contain and transmit avian reovirus
Mainly Affects
Liveability and egg quality
Use of modern anthelminthics to effectively kill both larve and adult worms. Removal of droppings from feeders and drinkers and pasture rotation and regular anti-parasite treatment (as locally approved), especially in young birds and Free range production system. The nutritional state of the bird also influence the development of immunity. Diets high in vitamins A and B (complex) increase the fowl's resistance to A. galli. Increasing levels of dietary calcium and lysine decreased the length and number of worms recovered.
Suggested Actions
  • Can be confirmed with clinical signs and gross lesions
  • Technical assistance recommended
  • Can be managed with feed additives, off-the-shelf medications
  • Diagnosis should be confirmed with rapid assays and/or a certified laboratory
  • Veterinary intervention is recommended

Impact on Egg quality


Impact on Liveability


Impact on Production


Overall Economic Impact


David E. Swayne. 2013.  Diseases of Poultry 13th Edition. page 1121

Y.M. Saif.2008.Disease of Poultry. 12th Edition. page 1038

Paul McMullin. 2004. A pocket Guide to Poultry Health and Disease. First Edition. page 180

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