Psittacosis is an infectious disease caused by the bacterium Chlamydia psittaci, primarily affecting birds, especially parrots, canaries, and pigeons. Humans can contract the disease through inhaling dust from dried bird droppings or secretions. Symptoms in humans may include fever, chills, headache, and respiratory issues. Diagnosis is typically made through blood tests or cultures, and treatment usually involves antibiotics. If left untreated, psittacosis can lead to severe complications, including pneumonia. Preventive measures include proper hygiene and avoiding close contact with infected birds.