Eosinophils are granulocytes with eosinophilic granules in the cytoplasm, mainly in the respiratory tract, digestive tract, genitourinary tract mucosal tissue, and peripheral blood, with a normal value of the reference range of (0.02-0.5) × 10^9/L. Eosinophils of 0 may be due to the following conditions: 1. Viral infections: For example, viral-induced upper respiratory tract infections, patients may have peripheral leukocytes Decrease in peripheral leukocytes as well as decrease in lymphocyte count. Some patients may have reduced eosinophils or even 0; 2. Typhoid fever: Patients may have reduced leukocytes, usually with neutropenia and eosinophils as the main manifestation; 3. Drug factors: Patients with long-term application of glucocorticoids may have reduced lymphocytes, reduced eosinophils or even 0; 4. Patients with burns may also have 0 eosinophils due to the stressful state of the body. In addition, patients with scarlet fever may also have 0 eosinophils. When a patient is found to have 0 eosinophils, he or she should go to the hospital in a timely manner and under the guidance of the doctor, improve other related tests to clarify the cause and then treat the cause. For example, patients with viral infections can be treated with antiviral and anti-inflammatory drugs under the guidance of a doctor. Patients with scarlet fever can be isolated and treated with penicillin and other medications as prescribed by the doctor.