S5136 Strongyloidiasis: A Mimicker of Recurrent Colitis and Failure to Thrive

Introduction: Strongyloidiasis is a soil-transmitted nematode infection caused by Strongyloides stercoralis. It's complex life cycle enables dormancy for decades. Immunocompetent people may have mild gastrointestinal, respiratory, or no symptoms, while, in immunocompromised hosts, on corticosteroids or immunosuppressants, it could be life threatening. Chronic strongyloidiasis can mimic conditions like colitis, inflammatory bowel disease (IBD), and malignancy. We present a diagnostically complex case of a woman with gastrointestinal symptoms, initial negative stool, pulmonary emboli, asthma exacerbations, failure to thrive, colitis on repeat imaging, and elevated tumor markers, ultimately found to have strongyloidiasis. Case Description/Methods: A 70-year-old Fujian speaking woman with history of asthma, hypertension, diabetes, hyperlipidemia and recent pulmonary emboli, presented recurrently with a 3-month complaint of persistent abdominal pain, nausea, vomiting, poor oral intake, and intermittent diarrhea. Examination showed mild lower abdominal tenderness, no peritoneal signs. She had persistent leukocytosis (white blood cell count: 14-21 × 103/µL), eosinophilia (>1.5 × 103/µL, elevated erythrocyte sedimentation rate (ESR: 76 mm/hr), and fecal calprotectin (972). Infectious work-up (Flu/RSV/Covid, Blood, Stool studies, and toxin) was negative. Tumor marker carcinoembryonic antigen (CEA) was elevated. Computed tomography abdomen/pelvis on multiple occasions showed diffuse wall thickening of the ascending and transverse colon with pericolonic stranding. Stool ova/parasite at the last presentation eventually showed few rhabditiform larvae of Strongyloides stercoralis. She received 2 days course of oral ivermectin with symptomatic improvement. Discussion: This case illustrates the diagnostic ambiguity as strongyloidiasis mimics recurrent colitis, asthma exacerbations, pulmonary embolism. Diagnosing strongyloidiasis requires a high index of suspicion due to nonspecific presentations, intermittent larvae shedding in stool. Initial testing may not reveal strongyloidiasis hence recurrent presentations and delayed diagnosis. However, eosinophilia, asthma, steroid use, persistent symptoms, and endemic history suggest helminthic activity. Strongyloides may cause colonic nodules, ulcers, lesions, and elevated CEA due to inflammation. The overlapping features of parasitic infection, inflammatory colitis, and malignancy require careful consideration. Steroid can trigger severe strongyloidiasis necessitating repeat testing before use.