There are at least six types of internal parasites (worms) that affect poultry, game birds, turkeys, & pigeons. Worms are caused when the bird ingests fecal matter or hosts (insects, earthworms, etc.) which have eggs in them. A large variety of symptoms are observed such as pale combs & wattles, droopiness, slow growth, lowered egg production, and in extreme cases death. They are very common in backyard and free-range flocks due to the likelihood of the birds coming into contact with other hosts. Control of worms is very important for the general health of your flock, as the presence of worms can reduce the birds' immunity to other diseases.
All birds including:
When: Young birds are more susceptible, however adult birds can also be affected
Why: Ingestion of viable eggs which can be found in droppings (fecal matter) and also in various hosts such as earth worms and insects.