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Cecal Worms

Other Names: Heterakis

The cecal worm (Heterakis gallinarum) is a type of internal parasite that infest the ceca. They are extremely common and thrive on the ground or litter of overcrowded bird enclosures. Cecal worms have a direct life cycle. Adult worms produce eggs while inside their host (the infected chicken), which it passes within its feces. The eggs remain in the soil or litter for several weeks or are ingested by another chicken. Once inside the chicken, the larvae hatch in the upper intestine and relocate to the ceca. Eggs are also ingested by earthworms, which are then consumed by the chicken, who becomes infected through the earthworm.
The main importance of the cecal worm is that it serves as a main vector for the transmission of Histomonas meleagridis, a protozoan parasite known to cause blackhead disease. Blackhead disease is of most significance to turkeys but can sometimes affect chickens. Chickens are often carriers of H. meleagridis and show no clinical signs but regularly shed its eggs in their feces. This is why it's important that chickens and turkeys are not raised together. It is also important not to raise turkey in the same area that was previously used to raise chickens, since H. meleagridis can survive for up to two years in its environment.


Cecal worms are transmitted to chickens through eating intermediate hosts (earthworms), or directly through contaminated water, feed, bedding, or soil.

Clinical Signs



  • History
  • Fecal test
  • Necropsy

Reported Cases

  • Case 1: Cecal Worms associated with Blackhead disease in a Chickens There was increased mortality of 3-4 days duration in a flock of 7-week old broiler breeder pullets. Affected birds were lethargic, inappetent, and had ruffled feathers and mild to moderate loss of pectoral muscle mass. A few birds had red-brown feces. Moderate to marked loss of pectoral muscle mass was present. Gross lesions varied with chronicity, ranging from marked hyperemia and mild ulceration of the cecal mucosa to extensive ulceration of the cecal mucosa with large fibrinonecrotic casts within the lumens. In virtually all birds, there was moderate to marked thickening of the cecal walls. The livers of several birds contained variably-sized, often coalescing, foci of necrosis. In a few of the birds, there was rupture of the cecum with extensive fibrinous peritonitis and airsacculitis. Small numbers of cecal worms (Heterakis gallinarum) were variably present in the cecal lumen. Liver: Hepatitis, granulomatous, necrotizing, multifocal to coalescing, moderate, with numerous protozoa, chicken, avian. Cecum: Typhlitis, lymphoplasmacytic, histiocytic, and heterophilic, diffuse, moderate, with protozoa and cecal core. Some microslides contain cross-sections of intraluminal cecal nematodes. Ref


Albendazole (Valbazen)Given to each bird orally. Measure out ¼ mL (per bantam) or ½ mL (per regular-sized breed). Repeat in 2 weeks.G Damerow
Safeguard 10% Liquid Dewormer for GoatsFenbendazole is used off-label in poultry. Add to the flock's drinking water source at a rate of 3 mL per gallon of water.G Damerow
Panacur or Safeguard Equine Dewormer 25 g Paste 10%Fenbendazole is used off-label in poultry. Given individually to each chicken orally, squeezed out in a pea-size portion and placed inside their mouth. Repeat in 10 days.G Damerow
(1% Ivermectin) Injectable for Cattle and SwineIvermectin is used off-label in poultry. The drug is given to each chicken orally or added to the flock’s water source.

If given by mouth - 0.25 mL per large size, 0.1 mL per bantam size.

If added to flock water source- 4 mL per gallon of water. Made fresh daily for 2 consecutive days.
G Damerow
Levamisole Soluble Drench Powder (46.8g)Levamisole is used off label in poultry. It's added to the flock’s water source.

Note- Chickens who are severely debilitated should not receive this medication, because it will impact their ability to fight infections.

Add to the flock’s drinking water source - at a rate of 10 mL per gallon of water for only 1 day.
G Damerow
Diatomaceous earthAdded as 2% of overall dietD Bennett; R Isabirye et al., 2019



  • Daily removal of feces accumulation in coops
  • Rotate pen every week or so
  • Pest control
  • Practice good sanitation

Scientific References

Good Overviews


Risk Factors

  • Poor sanitation
  • Overcrowding
  • Introducing new chickens from another flock
  • Stress