Numerous diseases can be associated with either tissue eosinophil
infiltration or blood eosinophilia.
For the latter, broad categories include:
1. Tissue-invasive parastic infections (as opposed to intestinal
parasites):
e.g. schistosomiasis, larva migrans, invasive amebiasis,
cysticercosis, etc.
2. Tumors
3. Allergic conditions
4. Hypoadrenal states (e.g. Addison's disease)
5. Rheumatologic diseases
Good references include: clinical hematology textbooks, eg. Williams
et al. Hematology.
An excellent description of eosinophils from a more cell biological
point of view can be found in Inflammation: Basic Principles and
Clinical Correlates, editors. John I. Gallin, Ira M. Goldstein, and
Ralph Snyderman, second ed, 1992, Raven Press, NY.