Endoscopic Detection and Molecular Confirmation of Ancylostoma ceylanicum with Atypical Gastrointestinal Manifestations: A Case Series

Abstract

Background Hookworm is a widely known soil-transmitted helminth (STH) traditionally linked to iron-deficiency anemia caused by chronic blood loss in the small intestine. The classical human pathogens are Ancylostoma duodenale and Necator americanus. However, emerging evidence indicates that Ancylostoma ceylanicum, a hookworm of cats and dogs, is a significant cause of human infection, particularly in Southeast Asia and other tropical regions. Its detection in human populations signals an evolving epidemiological landscape, challenging the previous notion that zoonotic hookworms have a negligible impact on human health.

Case Series This series presents three atypical cases that challenge classic paradigms of hookworm disease. In all cases, adult worms were retrieved from the colon by endoscopy and subsequently identified by molecular analysis. The first case is a young man with profound eosinophilia and watery diarrhea. Adult hookworms were found ectopically in the colon, an atypical site, demonstrating the worm’s potential for aberrant migration and a severe systemic immune response. The second case is an elderly male with multiple chronic conditions whose refractory anemia was unexpectedly attributed to a colonic infection discovered during a routine exam, underscoring hookworm as a treatable cause of anemia in geriatric populations. The third case is a young female with colitis-like symptoms. Colonoscopy revealed widespread superficial ulceration and live worms, highlighting the mimicry of inflammatory bowel disease.

Conclusion Collectively, these cases emphasize the diagnostic value of endoscopy in identifying hookworm infection, its diverse clinical manifestations beyond chronic anemia, and the requirement for the consideration of hookworm infection in the differential diagnosis of eosinophilia, unexplained colitis, and refractory iron deficiency across a wide demographic spectrum.