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Large Intestinal Roundworms, Ascaridia, Nematodes

Ascaridiasis is the infestation of Ascaridia galli (roundworms) in the intestines of ducks and other waterfowl. A. galli are large roundworms that can infect all species of birds but are found most commonly in domestic fowl such as chicken and sometimes turkey, geese, guinea fowls and ducks. A. galli are the largest nematode found in birds and can be found worldwide.

Free range or backyard waterfowl are commonly infected with A. galli. The parasite is transmitted to birds by ingesting different vector species that are carrying A. galli eggs (such as earthworms), feed or water contaminated by bird feces, or A. galli eggs from contaminated soil.

Disease from A. galli occurs when when normal body functions are impaired due to infestation of the parasite in the bird's intestines. The severity is related to the degree of impairment to the duck's body. Most common clinical signs of infection include weight loss, reduced growth rate or feed efficiency, diarrhea, decreased egg production in laying hens, enteritis and anemia. There is also speculation that A. galli may be associated with transmission of Salmonella and reovirus infections.

Heavy infestation of A. galli can cause intestinal blockage, resulting in death. The severity is dependent on the number of worms present. Ducks with a large number of worms can suffer from blood loss, slow growth, inflammation of the intestine and a greater risk of mortality.


Reduced feed consumption
Pale combs and wattles
Droopy wings
Poor body condition
Laying eggs with pale egg yolks
Weight loss
Decreased growth
Decreased egg production
Worms found in eggs or feces


  • History
  • Clinical signs
  • Fecal exam
  • Necropsy


MethodMethod Summary
Piperazine saltsadministered into feed (0.2-0.4%) or water (0.1-0.2%), or as a single treatment (50–100 mg/bird)
Levamisole25-50 mg/kg SC administered as a single dose
Flubendazole2.4 kg/ton in feed for 7 days
Fenbendazole20 mg/kg PO administered as a single dose
Ivermectin200 ug/kg SC or PO as a single dose
Hygromycin B


  • Practice strict sanitation of feeders and waterers to reduce contamination with bird feces
  • If the birds are confined to a pen outside, rotate access to different areas regularly to minimize build up of worm populations
  • Segregate birds by age groups, with particular care applied to sanitation of young birds
  • waterfowl should receive a diet which includes supplementation with vitamin A and B complex vitamins. Lack of these vitamins makes the birds more susceptible to worm infections.


Age Range

Can affect ducks of any age, however they are most damaging to young ducklings (< 12 weeks old).

Risk Factors

  • Unsanitary living conditions
  • Overcrowding of birds