A six-year-old child with yellow nasal discharge for half a year and a routine blood test showing white blood cells of 18.8×10^9/L is mostly indicative of a bacterial infection in the body. The white blood cell count of a six-year-old child is usually within the range of (5.0-12.0) × 10^9/L. If the routine blood test shows that the white blood cells are 18.8 × 10^9/L, it is likely to be due to gram-staining positive bacterial infections such as Streptococcus pneumoniae and Staphylococcus aureus, which will stimulate the body’s immune system to produce a large number of white blood cells after entering the bloodstream, leading to an elevated white blood cell count. The white blood cell count is elevated. If the white blood cell count is 18.8×10^9/L, other tests should be performed to clarify the cause of the disease, and the child should be encouraged to eat more vegetables and fruits and drink more water.