Extraordinarily high eosinophilia and elevated serum interleukin-5 level observed in a patient infected with Paragonimus westermani.

OBJECTIVE: Although eosinophilia is one of the typical clinical features of some helminth infections, the degree of eosinophilia in helminthiasis is usually 10% to 30% with a total white blood cell count of 10,000 to 20,000/mm3. Here we report a case of extraordinarily high eosinophilia (91%; absolute eosinophil count, 84,000/mm3) caused by Paragonimus westermani infection. To determine the mechanisms of eosinophilia, the levels of several eosinophilopoietic cytokines in the patient's sera were measured during the course of treatment.
METHODS: Serum levels of three cytokines, granulocyte-macrophage colony-stimulating factor, interleukin-3 (IL-3), and IL-5 were measured by enzyme-linked immunosorbent assay using commercial kits or our own assay system for IL-5.
RESULTS: Although the kinetic changes of IL-5 correlated well with eosinophilia, the serum IL-3 level remained below the detection level throughout the period examined. Although the granulocyte-macrophage colony-stimulating factor level was twofold to threefold higher than the normal level, its kinetics did not parallel the degree of eosinophilia.
CONCLUSIONS: These results show that Paragonimus westermani infection can induce an extraordinarily high level of eosinophilia with an associated increase in IL-5 production. Immunoserologic diagnosis for parasitic diseases should be included in the differential diagnosis of eosinophilia.