A Retrospective Longitudinal Study of Refugees With Eosinophilia at an Academic Center in the United States From 2015 to 2020.

Background: Refugees to the United States frequently have parasitic infections. If untreated, parasites can cause severe complications. The purpose of this study was to investigate the incidence, management, and outcomes of eosinophilia as a biomarker for parasites.

Methods: We conducted a retrospective longitudinal chart review of consecutive refugees attending 3 refugee clinics in Rhode Island that manage the health care of all pediatric and adult refugees.

Results: Among 812 refugees who met inclusion criteria, 147 (18.1%) had eosinophilia upon arrival and almost half had ≥1 symptom. The rates and severity of eosinophilia in those with predeparture presumptive treatment records who did (112/115, 97.4%) or did not (488/498, 98.0%) receive predeparture antiparasitic treatment were similar. All refugees with eosinophilia had ≥1 parasitic test in the United States. The most common attributable parasites were and . Overall, parasites were detected in 63 (42.9%) of 147 refugees with eosinophilia by either stool testing, serology, or blood smear, but testing was inconsistent and likely underestimated true incidence. Only some of the identified parasites typically cause eosinophilia. Forty-five (30.6%) refugees with eosinophilia received antiparasitics in the United States. Of 81 (55.1%) individuals who had repeat blood tests, eosinophilia had resolved in 52 (64.2%). Five individuals (3.4%) had alternative diagnoses, including eczema, myelofibrosis, and drug allergy.

Conclusions: Our findings support Centers for Disease Control and Prevention recommendations to screen for eosinophilia in newly arrived refugees. Follow-up after 3-6 months is critical to confirm resolution of residual eosinophilia, which frequently occurs after effective predeparture treatment or if eosinophilia persists, to diagnose active parasitic infections.