Imported Strongyloides stercoralis infections in Germany: descriptive study of cases over 5 years in a referral center in Berlin

BACKGROUND: Strongyloides stercoralis is a widespread helminth in tropical and subtropical regions, which can persist in humans for life through autoinfection. The clinical picture varies from asymptomatic to life-threatening hyperinfection syndrome. There is concern about increasing prevalence in Europe due to the number of cases imported by migrants and travelers. METHODS: This is a retrospective chart review of patients evaluated at the Charité Tropical Medicine outpatient clinic in Berlin, Germany. Cases were identified based on either a positive serologic test for Strongyloides (i.e., probable cases) or the detection of Strongyloides larvae in stool samples (i.e., confirmed cases). RESULTS: From April 2018 to November 2023, 162 patients with Strongyloides infection were identified. Diagnosis was confirmed in 49 patients (30.2 %) and probable in 113 patients (69.8 %). About half of the patients (48.8 %) were classified as migrants, who were diagnosed through screening in 48.1 %. Eosinophilia was present in 27.6 % of all patients, with no significant differences between migrants and non-migrants, or between probable or confirmed infections. In patients with a positive stool microscopy, only 8/37 (21.6 %) had a positive serology. CONCLUSION: Nearly half of the migrant cases were detected through serology as part of screening. Most patients had no eosinophilia, and the positivity of serological tests was very low in patients with positive stool microscopy. These findings highlight the usefulness of targeted screening strategies in risk populations and suggest implementing sensitive stool tests detecting larvae combined with serology, to improve case detection.