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Capillariasis

Thread Worms, Hairworm Infection, Capillara, Small Roundworms

Capillariasis is the name of the disease caused by infection with internal parasites from the Capillaria genus (also known as hairworms or threadworms). Adult Capillaria are very thin, "threadlike" nematodes, that are approximately 1 cm (0.39 in) long. Their eggs, which can only be seen using a microscope, are barrel-shaped and have clear pugs on each pole. There are several different species of Capillaria that are each known to invade specific regions inside the chicken's body. Some species (C. contorta and C. annulata) will invade the crop and esophagus, causing thickening and inflammation of the mucus membranes. Others (C. bursata, C. caudinflata, and C. obsignata) target the lower intestinal tract, causing inflammation, hemorrhage, and erosion of the intestinal lining. When Capillaria are present in high enough numbers, it can be fatal to the chicken.
Nematode speciesWhere FoundIntermediate HostDefinitive Hosts
Capillaria annuataEsophagus, cropEarthwormChicken, turkey, guinea fowl, partridge, pheasant, quail, goose, grouse
C. anatisSmall intestine, cecum, cloacaNoneChicken, turkey, partridge, pheasant, goose, duck
C. bursataSmall intestineEarthwormChicken, turkey, pheasant, goose
C. caudinflataSmall intestineEarthwormChicken, turkey, guinea fowl, partridge, pheasant, quail, goose, grouse, duck, pigeon
C. contortaEsophagus, crop, mouthNone or earthwormChicken, turkey, guinea fowl, partridge, pheasant, quail, duck
C. obsignataSmall intestineNoneChicken, turkey, guinea fowl, quail, pigeon, goose
Life cycle
Capillaria worms can have a direct or indirect life cycle, depending on the species.
Infected chickens will pass Capillaria eggs in their feces, which often gets mixed in with poultry bedding or soil, and sometimes feed and water. The eggs are so microscopic, that you cannot see them with the naked eye. You need a microscope in order to identify their presence, hence why fecal tests are used as a great preventative tool. Other chickens in the flock will ingest the eggs when forging, eating, or drinking. Once ingested, the eggs hatch in the chicken and develop and feed on their crop, esophagus, small intestines, or ceca. Upon reaching adult age, the worms will then lay their eggs which gets passed through the chicken in their feces.

Symptoms

Weakness
Loss of appetite
Foul odor
Lethargy
Diarrhea
Huddling
Changes in egg shell quality
Decreased egg production
Retarded growth
Weight loss
Poor body condition

Diagnosis

  • History
  • Fecal exam
  • Post mortem examination

Treatment

MethodDetails
AlbendazoleAdministered orally, 1/4 cc (mL) per bantam, 1/2 cc (mL) per large breed, repeated in 2 weeks.G 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
Tetramisole40 mg/kg
Note is not approved in the USA for use in commercial poultry
Khaziev GZ et al., 1975
Mebendazole5-25 mg/kg orally , every 12 hours for 5 daysEnigk K et al., 1973; Gundlach JL et al., 1987
Thiabendazole200-500 mg/kg with feedShang N et al., 2011

Prevention

  • Allow chickens to dust bath by providing an area with appropriate substrate
  • Frequently change bedding and clean coop area to minimize accumulation of chicken droppings
  • Conduct annual fecal test on flock members.

Scientific References

Risk Factors

  • Use of deep-litter systems
  • Unsanitary conditions (fecal build up)