This disease can be transmitted from infected birds to humans. Parrot disease, ornithosis, and chlamydiosis are other names for psittacosis. Chlamydia psittaci infects wild and domestic birds and poultry. Birds which contract the infection include parrots, canaries, pigeons, chickens, ducks, and turkeys. The time between exposure to Chlamydia psittaci and the onset of illness in caged birds ranges from three days to several weeks.
Birds can have a latent infection.
That means they appear healthy and do not show any symptoms now but they can show symptoms later. These infected birds carrying the Chlamydia psittaci bacteria may shed the organism intermittently or sometimes continuously for weeks or months. Stress associated with nutritional deficiencies, overcrowding, breeding, egg-laying and prolonged transport may cause birds with a latent infection to shed infectious agents. When shedding occurs, the infected birds excrete the bacteria in the feces and nasal discharges and can remain infective for several months. When a person breathes in Chlamydia psittaci bacteria, the lungs' defense mechanisms attempt to neutralize them.