Prevalence of Stronglyoides Stercoralis and Elevated Immunoglobulin E in Patients with Eosinophilia in a New York City Physician's Practice

Background The most common etiology of eosinophilia (EOA) in the United States is allergic disease. Steroid therapy may be advised. Strongyloides stercoralis (Ss) infection is also associated with EOA. Steroids can precipitate Ss hyperinfection syndrome with multi-organ failure. Therefore, Ss should be identified and treated in EOA prior to initiating steroids. Ss is common in the tropics and in the subtropics. While the prevalence of Ss in the U.S. is low (0-6.1%), it is higher in immigrant populations (0-46.1%) (CDC 2014).

AIM To determine the prevalence of Ss and elevated immunoglobulin E (IgE) in patients with EOA in a New York City physician's practice with a large Dominican Republic constituent.

Methods The ICD10 code D72.1 was used to identify patients with EOA (absolute eosinophil count > 500/uL) seen in the physician's practice between 10/01/15 (inception of ICD10) and 06/30/17. Chart review indicated that the majority of patients had been screened for Ss antibody, fecal ova and parasites (O&P), and elevated IgE (> 114 kU/L).

Results Twenty-nine patients had EOA. Thirteen (46%) of 28 patients tested had Ss antibody, 4 (22%) of 18 patients tested had O&P (Blastocystis hominis [Bh]), and 18 (72%) of 25 patients tested had elevated IgE. Ten patients had both Ss antibody and elevated IgE. Ten patients with Ss antibody also had O&P testing, which did not detect Ss. Twelve patients with Ss received ivermectin (1 declined) and all 4 patients with Bh received metronidazole. AEC normalized following treatment in all 9 Ss patients (3 were lost to follow-up) and in all 4 Bh patients restudied.

Discussion The high prevalence of elevated IgE in this cohort is consistent with allergic disease being a common etiology of EOA. The high prevalence of Ss in this cohort underscores the importance of testing for Ss in EOA, particularly in immigrant populations. During acute Ss infections, stool larval output is large and O&P yield is high. During chronic Ss infections, immune response and EOA decrease larval production, which diminishes O&P yield; Ss serology should be performed. Diagnosis and treatment of Ss in EOA is essential to avoid clinical deterioration, particularly in patients who may receive steroids.