Hookworm Infection: A Neglected Cause of Overt Obscure Gastrointestinal Bleeding

Abstract

Hookworm infections are widely prevalent in tropical and subtropical areas, especially in low income regions. In the body, hookworms parasitize the proximal small intestine, leading to chronic intestinal hemorrhage and iron deficiency anemia. Occasionally, hookworms can cause overt gastrointestinal bleeding, but this is often ignored in heavily burdened individuals from endemic infectious areas. A total of 424 patients with overt obscure gastrointestinal bleeding were diagnosed by numerous blood tests or stool examinations as well as esophagogastroduodenoscopy, colonoscopy, capsule endoscopy or double-balloon enteroscopy. All of the patients lived in hookworm endemic areas and were not screened for hookworm infection using sensitive tests before the final diagnosis. The patients recovered after albendazole treatment, blood transfusion, and iron replacement, and none of the patients experienced recurrent bleeding in the follow-up. All the 31 patients were diagnosed with hookworm infections without other concomitant bleeding lesions, a rate of 7.3% (31/424). Seventeen out of 227 patients were diagnosed with hookworm infections in the capsule endoscopy (CE), and 14 out of 197 patients were diagnosed with hookworm infections in the double balloon enteroscopy (DBE). Hookworm infections can cause overt gastrointestinal bleeding and should be screened in patients with overt obscure gastrointestinal bleeding (OGIB) in endemic infectious areas with sensitive methods. Specifically, the examination of stool specimens is clinically warranted for most patients, and the proper examination for stool eggs relies on staff's communication.

Keywords: Ancylostoma duodenale; Necator americanus; capsule endoscopy; double balloon enteroscopy; hookworm; obscure gastrointestinal bleeding.

Fig. 1

Final diagnosis of cases with obscure gastrointestinal bleeding (OGIB). In total, 31 patients with overt OGIB were diagnosed with hookworm infections, a rate of 6.9%.

Fig. 2

Hookworm infections in the patient’s small bowel, as observed with endoscopy. (A) Most hookworms frequently appeared between the distal duodenum and the distal jejunum. (B, C) Hookworms appeared with reddish bodies attached to the intestinal mucosa. (D) Hookworms feeding on the intestinal mucosa with a hemorrhagic spot. (E) Blood oozing was found at the hookworms’ site of attachment.

Fig. 3

The hemoglobin (Hb) of 30 cases recovered after treatment compared to before treatment. The 31 patients did not experience any recurrent bleeding, and their Hb increased significantly throughout treatment after 6 months.