Absolute eosinophils refer to the number of eosinophils, a type of white blood cell, present in a blood sample. An absolute eosinophil count is a blood test that measures the number of eosinophils in a sample of blood. Eosinophils become active when you have certain allergic diseases, infections, and other medical conditions. A normal eosinophil count is less than 500 cells per microliter (cells/mcL) . A high eosinophil count may indicate a parasitic infection, an allergic disorder like asthma or hay fever, autoimmune conditions, or a reaction to certain medications. An eosinophil count can help diagnose certain conditions, but it cannot tell if the higher number of cells is caused by allergy or parasite infection.