UNRECOGNIZED PARASITIC INFECTION AS A CAUSE OF PERSISTENT EOSINOPHILIA IN AN INNER-CITY ALLERGY CLINIC POPULATION

Abstract

<h3>Introduction</h3> Persistent peripheral blood eosinophilia (absolute eosinophil count (AEC)> 500 cells/mL) is frequently a manifestation of a serious medical problem. Nevertheless, previous studies have shown that patients with persistent eosinophilia are often not adequately evaluated for possible underlying causes. <h3>Methods</h3> Patients from an inner-city Allergy clinic from 2020-2022 with AEC>500 cells/mL at least on 2 occasions and no established cause were evaluated. <h3>Results</h3> A total of 82 patients were enrolled. Patients were predominantly female (72%), with mean age of 50 years (range 15-97), of Hispanic (42%) and African- American (32.5%) race. Hypereosinophilia (AEC>1500 cells/mL) was found in 17% (14/82) patients, with the highest AEC of 40,000 cells/mL. Co-morbid conditions included allergic rhinitis [(80.4% (66/82)], asthma [(53.6% (44/82)], nasal polyposis [(12% (10/82)], and eczema [(8.5% (7/82)]. Overall, 30% (24/75) of the study population tested positive for some parasitic infection: <i>T. canis</i> (25.3% (16/63)); <i>S. stercoralis</i> [10.9% (8/73), 6% (4/63) had both infections]; <i>B. hominis</i> (4% (1/23). One had <i>W. bancrofti</i> and one had <i>S. mansoni</i>. 18 of 24 patients received anti-parasite therapy. Post-treatment AEC was measured in 9 of the treated patients and eosinophilia resolved in all of them. 23% (12/52) of the study population had elevated IgG4(>86 mg/dL) but none had evidence of IgG4- related disease. 7% (4/56) of study population had elevated IL-5 levels (>3 pg/mL). 3 of these 4 patients had parasitic infections. <h3>Conclusion</h3> Parasitic infection is a common cause of unexplained persistent eosinophilia in inner-city patients. Role of elevated IL-5 in different causes of eosinophilia needs further investigation.