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Nematodiasis, Ascaridiosis, Helminthiasis, Helminth Infection, Nematode Infection

The large roundworm (Ascaridia galli) is one of the most common nematodes found in chickens. They are a type of intestinal parasite which have a simple and direct life cycle. They are transmitted to chickens through fecal-oral route. An infected bird spreads it to others through their feces. Within the feces, tiny eggs are present which were passed from the adult worms laying them in the infected bird's intestines. Other birds become infected by eating food, drinking water, or pecking at the ground which has been contaminated with the infected birds feces. Once eggs are shed in the feces of the infected birds, they are very resistant to environmental conditions, and able to survive in a wide range of temperatures. They have been reported to be capable of remaining in the soil for up to 66 weeks under certain environmental conditions.

Transmission and Life Cycle

Ascaridia galli life cycle in chickens

Damage caused by Roundworms

A. galli invade and cause varying degrees of damage to the chicken's gastrointestinal system. A. galli are known for specifically inflecting damage to the chicken's small intestines. Mild infestations can often go unnoticed, however in severe cases with heavy worm loads, it can impact nutrient absorption, cause intestinal blockage, anemia, weight loss, increased urates, atropic thymus glands, and hypoglycemia, leading to death of the bird.

Clinical Signs

Reduced appetite
Decreased growth
Pale comb/wattles
Worms found in feces


  • History
  • Clincial signs
  • Physical exam
  • Fecal test
  • Necropsy


Citrus peel ethanolic extractFeed additive - 600-1200 mg/kg for 14 daysA Abdelqader et al., 2012
Garlic (Allicin)2.5 mg/bird
Drinking water - 1.5 mg/L of water daily for 5 days
F Velkers et al., 2011
Turmeric (Curcuma longa) root extract200-600 mg/kg of body weightAlrubaie Al, 2015
AlbendazoleAdministered orally, ¼ cc (mL) per bantam, ½ cc (mL) per large breed. Repeated in 2 weeks.G Damerow
Fenbendazole (liquid)3 cc (mL)/gal in water for 3 daysG Damerow
Fenbendazole (paste)Pea-size dose/bird, administered orally. Repeat in 10 daysG Damerow
Fenbendazole (powder)1 oz dissolved in 1 cup (240 mL) of water, mixed with 15-20 lb (3-4 g/kg feed) for 1 dayG Damerow
Ivermectin (drench or injectable)Administered orally - 1/4 cc (mL) per large breed chicken, 6-7 drops (0.1 cc) per bantam.
Administered in drinking water - 4 cc (mL)/gal of water, for 2 days.
G Damerow
Levamisole (drench)Administered orally - 1/4 cc (mL)/lb body weight.
Administered in drinking water - 10 cc (mL)/gal for 1 day. Repeat in 7 days, and repeat again in 7 days.
G Damerow
Levamisole (injectable)Injected under the skin, 1/4 cc (mL)/s lb body weight (25 mg/kg).G Damerow
PiperazineAdministered orally - 50 mg/bird (under 6 weeks of age), 100 mg/bird (over 6 weeks of age) or according to label. Repeat in 7-10 days.
Administered in drinking water - 3 cc (mL)/gallon of water, or according to label. Repeat in 7 days.
G Damerow



  • Maintaining good sanitary practices; since the eggs take 10 to 12 days to become infective once shed in droppings, if the droppings are removed then it reduces the chances birds accidentally consume them.
  • Occasionally providing apple cider vinegar in drinking water (20ml/L of water), however only should be used in non-galvanized drinkers.
  • If the birds are confined to a pen outside, rotate access to different areas regularly (once a weed) to minimize build up of worm populations
  • Discourage birds from eating off of the ground - Elevate feeder and waterer to discourage fecal contamination and clean and disinfect equipment daily.
  • Segregate birds by age groups, with particular care applied to sanitation of young birds
  • Chickens 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
  • Conduct routine fecal tests

Scientific References

Good Overviews


Age Range

Young chicks less than 12 weeks old are more susceptible. Chickens build a resistance with age.

Risk Factors

  • Keeping birds confined in one area on a continuous basis without rotating pasture lots.
  • Feeding birds kitchen scraps
  • Smaller birds, due to their body weight differences
  • Unbalanced diet
  • Use of a deep-litter bedding system

Also Consider