Psittacosis (Ornithosis; Chlamydia psittaci)
Infectious agent: Chlamydia psittaci
Description of illness: Psittacosis (Ornithosis) is an infectious disease caused by Chlamydia psittaci, a type of bacteria that most often infects birds. Psittacosis causes a wide range of symptoms in people, including fever, headache, and a dry cough. This illness can also cause pneumonia (a lung infection) that may require treatment or care in a hospital. Rarely, psittacosis can be deadly.