Eosinophilia
AFL 7/30/02
Eosinophilia- Generally accepted as > 450 eos/microliter. Technically,
eosinophilia is an accumulation of eos in the blood or tissue. Eos tightly
regulated by body, usually only 1-3% of peripheral blood leukocytes. - small # in
peripheral blood, and in tissues majority are in GI tissues
ETIOLOGY Most common cause worldwide is helminthic infxn, most common
cause in industrialized nations is atopic disease.
Many use the mnemonic NAACP : Neoplasm, Addison’s, Allergy, Collagen Vasc
Dz, Parasites
• Parasites: Usually helminithic (worms)- requires tissue invasion to trigger
eosinophilia, not just presence in the gut (further broken down into type of
worm- annelides (leeches), nematodes (roundworms), cestodes (tapeworms),
trematodes (flukes)). Stimulate TH-2 response, which is characterized by
elevated IL-4 and IL-5, both of which stimulate eosinophila. Exception to
nematode rule are Isopora and Dientameoba fragilis, both enteric protozoans
which can cause eosinophilia.
-Schistosomiasis (fluke): Most eosinophilia with acute systemic illness
(“Katayama fever”) with initial infecion, especialy with mansoni and japonicum.
-Toxocara: nematode carried by cats and dogs, causes visceral larva migrans
and nematode endophthalmitis. Humans are aberrant host. Causes small
granulomatous liver lesions but can cause extensive hepatic necrosis.
Granulomatous lesions may be seen in every organ. Dx; triad of hepatomegaly,
eos, hyperglobulinemia. Liver bx rarely diagnositc. ELISA- limited utility, stool
O&P useless usually.
-Trichinella- pork nematode. Commonly causes eosinophilia with migratory
phase of infxn
-Strongyloides Transient lung infxn, chronic infxn of gut, can have persistent
autoinfection, and therefore infxn years after exposure. Hyperinfection syndrome-
fever, PNA, GNR bacteremia, +/- meningitis.
-Tropical eosinophilia- Pulmonary sx- asthma, wheezing, cough, fleeting
pulm infiltrates, +/- LAN and hepatomeg. .3000/mm3 eos, elevated IgE, and
anitbodies t