Case report - Duodenal Strongyloidiasis: a rare cause of melena / Estrongiloidíase duodenal: uma causa rara de melenas

A 75-year-old Black female with a three-month history of unintentional weight loss presented to the emergency department with a two-day history of melena and signs of decompensated anaemia. She denied the use of non-steroidal anti-inflammatory drugs, corticosteroids, immunosuppressive therapy, alcohol consumption, or previous gastrointestinal symptoms. Physical examination revealed marked pallor, tachycardia and systolic murmur. Hemogram showed severe anaemia with a haemoglobin level of 2.5 g/dL. The severe anemia was most consistent with chronic gastrointestinal blood loss, possibly with an acute component, given the recent onset of melena. An abdominopelvic CT scan was performed, which did not reveal evidence of solid organ malignancy or lymphoproliferative disease. Additionally, a formal haematology evaluation was requested, and no underlying hematologic disorder or immunodeficiency was identified. After stabilisation, esophagogastroduodenoscopy was performed, and revealed erythematous and eroded duodenal mucosa, with several motile larvae on the surface, as shown in Figures 1 and 2. Targeted biopsies were performed directly from the areas containing the larvae. Histopathological analysis confirmed the presence of Strongyloides stercoralis eggs and larvae, as shown in Figures 3 and 4. The patient was treated with ivermectin 200 µg/kg single dose, showing progressive clinical and laboratory improvement. Albendazole 400mg was also given in a single dose to cover other common helminths in our region, given the epidemiological context and the likelihood of polyparasitism. A follow-up esophagogastroduodenoscopy was performed a month after the treatment, and demonstrated complete mucosal healing. The patient remained asymptomatic, regained weight, and repeated stool examinations were negative for parasites. Further tests were done targeting risk factors for strongyloidiasis and other underlying causes for immunosuppression, and were ruled out. Preventive and hygiene measures were reinforced with the patient and extended to household members. Strongyloidiasis is a major neglected tropical disease that can persist lifelong and, in some cases, lead to fatal hyperinfection1. Gastro duodenal involvement is endoscopically heterogeneous and frequently nonspecific, and overt upper gastrointestinal bleeding remains an uncommon presentation, underscoring the importance of careful duodenal inspection and targeted biopsies in endemic settings2. Endoscopic findings may reveal mucosal oedema, erythema, erosions, ulcerations, and, in rare cases, visible larvae on the mucosal surface3. Treatment with ivermectin is effective, well tolerated, and associated with few side effects, with albendazole as an alternative therapy4. This case deserves special attention because melena as the initial manifestation of strongyloidiasis may delay diagnosis, particularly in elderly patients in whom more common causes of upper gastrointestinal bleeding are usually suspected first. In endemic regions, parasitic infection should be considered in patients with unexplained anaemia or gastrointestinal bleeding, even in the absence of immunosuppression. Careful inspection of the duodenum during endoscopy and targeted biopsies of subtle mucosal abnormalities are essential for diagnosis, as stool examinations may be negative and endoscopic findings can be nonspecific. This case highlights the importance of considering parasitic infections in elderly patients with unexplained gastrointestinal bleeding, particularly in endemic regions, and reinforces the diagnostic value of endoscopic recognition and targeted biopsy for Strogyloides stercoralis.