Diphyllobothrium latum

A 37-year-old woman is hospitalized for small bowel obstruction. Two months ago she traveled around the Baltic Sea and ate several meals consisting of raw fish. Temperature is 38.1°C (100.6°F), blood pressure is 125/77 mmHg, and pulse is 90/min. Laboratory studies reveal a hemoglobin of 9.1 g/dL (reference range: 12.0-16.0 g/dL) and mean corpuscular volume of 109 μm3 (reference range: 80-100 μm3). A stool sample is collected and is found to contain several eggs. Which of the following pathologies is most likely responsible for this patient’s clinical presentation?