There are five types of white blood cells: neutrophils, eosinophils, basophils, the above three are called granulocytes, and the remaining two without granules are lymphocytes and monocytes. In addition to the total number of white blood cells, the number of these five types of cells is also indicated in the routine blood count, among which lymphocytes or neutrophils are usually the most numerous. If there is a parasitic infection, the eosinophil count is likely to be significantly higher, and in the case of EBV infection resulting in infectious mononucleosis, the number of monocyte counts will be increased. In the case of elevated eosinophil counts, there may be some allergic condition.