[Parasite-induced hypereosinophilia].

Blood hypereosinophilia (eosinophilia count of more than 500 per microliter, i.e., 0.5.10(9)/L) is a laboratory finding that requires a careful workup. Review of the patient's medical history and clinical examination can usually rule out non-parasitic causes. Parasitic infections must be sought by examination of stool, urine, and blood examinations and by serological tests. These examinations, with special techniques for cosmopolitan and tropical parasites and for digestive or tissular parasites, must be repeated. Improvement of blood eosinophilia and of the serum antibody titers is one criterion of treatment effectiveness.