Birds can suffer from various lung and airway diseases, sometimes due to a parasitic infection. One such (protozoan) parasite is the gapeworm, which infests the respiratory tract of birds -- many times finches and canaries. The gapeworm is also common in birds housed outdoors; it is rarely found in caged birds.
Due to the parasite's infestation of the bird's tracheal wall, it will suffer from an irritated respiratory tract and have difficulty breathing. The infected bird will also tend open its beak wide (gape) for air. Sometimes during advance stages, the birds will die from lack of oxygen. Birds with gapeworms will also usually have pneumonia.
If your bird shows any sign of respiratory distress like: difficulty breathing, sneezing, coughing, wheezing, noisy breathing, along with lack of appetite, weight loss and weakness, you must take the bird to the veterinarian for examination.
Term used to imply that a situation or condition is more severe than usual; also used to refer to a disease having run a short course or come on suddenly.