What are chicken diseases where comb turns blue?

* Avian influenza (fowl plague) is a highly contagious viral disease that can affect chickens, turkeys, ducks, geese, and other birds. Symptoms include respiratory distress, coughing, sneezing, nasal discharge, conjunctivitis, and swelling of the head and neck. The comb and wattles may also turn blue or purple. Avian influenza can be fatal, and there is no cure.

* Fowl cholera is a bacterial disease that can affect chickens, turkeys, ducks, geese, and other birds. Symptoms include loss of appetite, depression, diarrhea, and coughing. The comb and wattles may also turn blue or purple. Fowl cholera can be fatal, and there is no cure.

* Marek's disease is a neoplastic disease that can affect chickens and turkeys. Symptoms include weight loss, depression, diarrhea, and paralysis. The comb and wattles may also turn blue or purple. Marek's disease can be fatal, and there is no cure.

* Blue comb disease is a viral disease that affects chickens. Symptoms include diarrhea, dehydration, and loss of appetite. The comb and wattles may also turn blue or purple. Blue comb disease can be fatal, and there is no cure.