Three plus white blood cells are usually indicative of an infection in the body. If white blood cells are found to be elevated in the blood analysis, consider an infection in the respiratory tract, gastrointestinal tract, or urinary tract. If the symptoms favor fever with cough and sputum, it is an infection of the upper respiratory tract. If there is abdominal pain, diarrhea, mucousy stools, and white blood cells are found in the stool routine, it is considered to be an infection of the gastrointestinal tract caused by a dysbiosis of the gastrointestinal flora. If white blood cells are found in the urine routine, depending on the white blood cell plus or minus number, upper or lower urinary tract infections of different degrees are considered. In the case of upper urinary tract infection, the fever is usually more severe, above 39-40℃, and the systemic symptoms are more obvious. In the case of lower urinary tract infections, the infection is usually recurrent and persistent, such as urinary tract infection or cystitis. Middle-aged and elderly women are often prone to attacks because of their physiological characteristics. Therefore, according to the different symptoms, combined with laboratory tests, we can determine where the infection is located.