In the initial stages of the disease, symptoms such as fatigue, sore throat, headache, muscle pain, and varying degrees of fever may occur. Two to three days later, significant respiratory symptoms appear, including paroxysmal, irritating coughs with a small amount of phlegm, sometimes purulent or blood-streaked. The fever persists for two to three weeks before subsiding, but the cough may continue for a while even after the fever has dissipated, often accompanied by substernal pain. Appropriate diagnostic tests should be conducted for confirmation.