Eosinophils are white blood cells that increase in response to parasitic infestations. They coordinate with other immune cells, including Secretory IgA (SIgA), to help protect mucosal surfaces from parasitic damage.   On a lab test, they are shown as a % of the total white blood cell (WBC) count. In our clinics, we consider 6% or higher elevated.   Eosinophils typically rise in response to helminthic infections, including roundworms, tapeworms, and flukes.