Refugees with Eosinophilia: Diagnostic Considerations

Abstract & Commentary

By Michele Barry, MD, FACP

Professor of Medicine, Co-Director, Tropical Medicine and International Travelers' Clinic, Yale University School of Medicine

Dr. Barry is a consultant for the Ford Foundation, and receives funds from Johnson & Johnson.

Synopsis: Many refugees arriving in the U.S. have persistent eosinophilia diagnosed and often are referred to travelers' clinics for diagnostic work-up. What does one consider in planning such a workup?

Source: Seybolt LM, et al. Diagnostic Evaluation of Newly Arrived Asymptomatic Refugees with Eosinophilia. Clin Infect Dis. 2006;42:363-367.

Seybolt and colleagues performed a retrospective analysis of refugees seen as part of a 2-visit health evaluation at Boston Medical Center from October 1998 through May 2002. Eosinophilia was defined as an absolute eosinophil count of > 450 cells/µL. Demographic data was abstracted along with results of stool examinations for ova and parasites, and serologic studies for antibodies to Strongyloides stercoralis, schistosomal and filarial species. Eosinophilia was present in 12% of asymptomatic, newly-arrived refugees screened. Pathogens were identified in stool samples of 29% of 265 patients. Serologic testing was performed in only 45% of patients but, of these results, schistosoma serology was positive in 22% (15 patients), S. stercoralis in 39% (45 patients), and filarial serology in 18 (51%) of 35 patients tested. Most subjects with pathogens identified were children and more than half were male. The most common stool parasite isolated was one not associated with eosinophilia (ie, Giardia lamblia), suggesting that serological testing aimed at looking for other sources of eosinophilia should be performed, even if the presence of pathogens in stool samples is documented.

Commentary

Eosinophilia in a refugee population is common and often reflects tissue-invasive helminths rather than the diagnosis of an atopic or allergic skin condition, commonly seen in US populations. Eosinophilia has been assessed in a traveler's population and is a poor marker of parasitic diseases.1 However, refugees who have had prolonged exposure to helminths and different economic settings have an increased risk of contracting parasitic infections, and so eosinophilia becomes an important diagnostic clue. Seybolt et al have attempted to demonstrate that serologic testing for schistosoma species, filaria species, and strongyloidiasis might be of benefit in diagnosing patients with more severe eosinophilia.

Not all patients in this report received a serologic evaluation, nor do Seybolt et al present follow-up data; thus, no conclusions as to cost-effectiveness of serologic testing or even resolution of eosinophilia can be made. Furthermore, cross-reactivity of antibody testing and persistent presence of antibodies in patients with past infections may have confounded their results.

However, despite these limitations, this paper remains an excellent reminder that not all asymptomatic eosinophilia can be identified by stool examinations for ova and parasites, and serologic testing for S. stercoralis, schistosoma and filarial species should be appropriately obtained for patients from regions where these pathogens are endemic. Nutman, in an accompanying editorial, suggests that when cost is an issue for refugee populations such as Southeast Asians in which strongyloidiasis and hookworm are common, single dose ivermectin and/or albendazole treatment may be empirically indicated.2,3

References

  1. Libman MD, et al. Screening for Schistosomiasis, Filariasis, and Strongyloidiasis Among Expatriates Returning from the Tropics. Clin Infect Dis. 1993;17:353-359.
  2. Nutman TB. Asymptomatic Peripheral Blood Eosinophilia Redux: Common Parasitic Infections Presenting Frequently in Refugees and Immigrants. Clin Infect Dis. 2006;42:368-369.
  3. Muennig P, et al. The Cost-Effectiveness of Ivermectin vs Albendazole in the Presumptive Treatment of Strongyloidiasis in Immigrants to the United States. Epidemiol Infect. 2004;132:1055-1063.