Diphyllobothrium latum Mimicking Subacute Appendicitis

Diphyllobothrium latum (D. latum) infection in humans is uncommon in the United States. Although there has been a drastic decline in the report of D. latum infection in this region, physicians should be aware of an uncommon presentation and its clinical relevance. We report a case of 55-year-old female of Ecuadorian/Peruvian origin who presented with an unknown cause of chronic right lower quadrant abdominal pain for 2 months without other particular symptoms. Initial workup revealed evidence of iron deficiency anemia, and stool occult blood test was positive. She was scheduled for a colonoscopy to assess the source of occult gastrointestinal bleeding. During her bowel preparation, she passed a 25 cm long white tapeworm-like material confirmed microscopically. Despite passing a worm she continued to have abdominal pain. During the colonoscopy, another worm was found lodged in the appendiceal orifice. The colonoscopic images revealed a segmented tapeworm showing contractile motility, approximately 12 cm in length and 6 mm wide in the appendiceal orifice. The scope was unsuccessful in removing the worm. The parasitological and microbiological examination of the passed worm was positive for D. latum. D. latum a fish tapeworm that infects humans after the ingestion of raw or undercooked fish. The patient had a history of often eating lightly marinated raw fish (“ceviche”) in Peru several months before presentation. It is uncommon for D. latum infection to present with iron deficiency anemia. As the worm absorbs approximately 80% of dietary vitamin B12, prolonged D. latum infection usually causes vitamin B12 deficiency and megaloblastic anemia, which is reported to affect about 40% of cases. Abdominal pain related to mechanical obstruction is reported, but this case is unique in that the worm preferentially attached to the appendiceal orifice causing subacute focal appendiceal pain. She was treated with a single dose of oral praziquantel. After the treatment, she developed minor cramping for the next 2 days which resolved by day 3, and recalled passing half-inch sized pieces of white tissue and subsequently improved. Although D. latum infection is an uncommon cause of chronic abdominal pain with iron deficiency anemia, it is crucial to consider because of the potentially treatable outcome.