Worms are typically transmitted from bird to bird through the fecal-oral route. This is where worm eggs are excreted in droppings and then ingested by birds that scratch and peck at the soil, litter, or droppings. Ingestion of infected earthworms, slugs and other secondary hosts can also spread parasitic worms.
The most common intestinal worms that infect laying hens include large roundworm, caecal worm and hairworm. Roundworms, are the largest worms affecting poultry.