Capillaria is a minute, thread-like worm that infects the esophagus, crop and intestine of chickens. It burrows into the organ lining, causing severe inflammation.

Hairworm Symptoms
Signs of hairworm infection include paleness, diarrhea and wasting. It can be fatal if severe cases are left untreated.

Can it spread?
As with other intestinal parasites, like roundworm or coccidiosis, hairworm spreads when eggs are passed through the feces and remain in the soil until ingested by the chicken. However, some Capillaria species use earthworms as intermediate hosts, complicating prevention.

Hairworm Prevention
Capillariasis is a problem in floor pens, where parasite egg numbers build up in the soil over time. Rotating the pen location, controlling earthworm population and changing the topsoil yearly will reduce the risk of infection. Hygromycin B is a preventive medicine that can be added to chicken feed, but it’s seldomly added to commercially bagged feed. Consult your veterinarian before adding it to your flock’s feed.

Hairworm Treatment
Piperazine treatment, used for roundworms, is not effective because Capillaria live deep in the lining of the gastrointestinal tract. Larger-than-recommended doses of Hygromycin B may be required to save chickens with severe infestations. Consult your veterinarian before administering such a dose to your flock.

About the Authors: Dr. Jose A. Linares, DVM, ACPV, is the Resident Director of the Texas Veterinary Medical Diagnostic Laboratory, Poultry Diagnostic Laboratory in Gonzales, TX. Dr. John El-Attrache, PhD, is an Assistant Professor in the Department of Veterinary Pathobiology in the College of Veterinary Medicine at Texas A&M University.