Chlamydia psittaci is a type of bacteria that causes psittacosis, a respiratory disease that can be transmitted to humans from infected birds, particularly parrots and pigeons. There are several synonyms for Chlamydia psittaci, including Chlamydophila psittaci, avian chlamydiosis, and ornithosis. Infections with this bacterium can range from mild flu-like symptoms to severe pneumonia, and can be fatal in rare cases. The infection is commonly contracted through inhalation of contaminated dust, feathers, or droppings from infected birds. It is important for individuals who work with birds or in the poultry industry to take precautions to prevent exposure to this bacterium, such as wearing protective clothing and masks, and practicing good hygiene.