Disseminated Strongyloides stercoralis infection diagnosed by metagenomic next-generation sequencing of a cell-free DNA blood sample in a patient with hematologic malignancy in Germany: A case report

BACKGROUND: Rare infections that are atypical for Central Europe are increasingly relevant due to global migration, climate change, and the widespread use of immunosuppressive therapies. Diagnosing such infections is often delayed or missed entirely because conventional testing relies on prior clinical suspicion and region-specific test panels. Hypothesis-free metagenomic next-generation sequencing (mNGS) offers a promising diagnostic strategy in these cases. CASE PRESENTATION: We report a case of disseminated Strongyloides stercoralis (S. stercoralis) infection with hyperinfection syndrome in a man undergoing B-cell-depleting lymphoma therapy. The patient presented with gastrointestinal and pulmonary symptoms, weight loss, and eosinophilia. Conventional microbiological and serological testing failed to identify a cause. Diagnosis and relevant bacterial and fungal coinfection were established using mNGS (DISQVER) from blood-derived cell-free DNA. Treatment with ivermectin and albendazole led to rapid clinical improvement, and the patient recovered completely. CONCLUSION: This case illustrates the diagnostic challenges posed by rare infections in immunocompromised patients in nonendemic regions. It highlights the growing need for broad, rapid, and hypothesis-independent diagnostic tools such as mNGS, which can play a key role in identifying unexpected pathogens and guiding early targeted therapy in high-risk populations.