- Though some birds with psittacosis don't display any signs or symptoms, others lose feathers or change their eating habits.
- One species, C. psittaci, causes psittacosis (so-called parrot fever), a respiratory infection transmitted from birds to people.
- The probability that a pneumonic illness in a budgerigar owner is due to psittacosis increases when the patient says that a pet bird has recently died.
- Exposure to the dust from nesting material and dried droppings can cause psittacosis, a respiratory disorder.
- C. psittaci causes a rare disease called psittacosis (also known as ornithosis).