[Variation in eosinophilia and measures of pollen counts of grasses (Poaceae) and ragweed (Ambrosia) in the Rhone valley].

Sensitivity to ragweed pollen, along with grasses pollen, is the leading cause of pollen-induced allergy in our region. Our study focuses on the variation of eosinophilia levels in the blood taken from a sample of the general population during both ragweed and grasses pollination periods. The pollen trap located in the central Rhône River Valley region has provided weekly counts since 1995. The Etablissement Français du Sang Rhône-Alpes-Valence routinely checks hypereosinophilia in the blood through systematic analysis after a blood donation. Average cumulative pollen counts for grasses and ragweed present an interesting correlation with the levels of hypereosinophilia measured at the end of the summer.