In this case history, a 49 year-old man handled a parakeet with a respiratory illness on February 7. On March 9, he experienced intense pain in his legs, followed by severe chills and headaches. On March 16, he had chest pains, cough, and diarrhea, and his temperature was 40°C. Appropriate antibiotics were administered on March 17, and his fever subsided within 12 hours. He continued taking antibiotics for 14 days. Identify each period in the pattern of disease that he experienced. Note: The disease is psittacosis. Can you find the etiology?