The capillaria plica look like trichuris but smaller and rougher. Capillaria plica and Capillaria felis cati are rare parasites of dogs and cats, respectively. Capillaria is generally found in the eastern United States. It is not of great importance since it rarely causes disease except in young fox. Its eggs can easily be confused with those of the lungworms or whipworms.
The life cycle of this parasite still eludes us. It may be direct, or it may involve the earthworm as an intermediate host. Adult worms lay eggs in the urinary bladder and these are passed through the urine. Larvae develop in the environment and are somehow ingested, either because of urine contamination of food or water, or through eating infested earthworms.
