A middle-aged man with abdominal pain and fatigue

A 38-year-old male came to the outpatient department with complaints of persistent fatigue and general malaise since past two months. He mentioned that he felt too weak to carry out his daily fishing activities and experienced a gradual loss of energy and stamina. He reported mild abdominal pain, indigestion and diarrhea as well as noticed unknown segments in stool. He also reports consuming a significant amount of meals with fish from fresh or brackish water which he consumes during his long fishing expeditions. 

On physical examination, the patient appeared noticeably pale and had glossitis. He had mild tingling sensation in his hands and feet. Laboratory investigations revealed macrocytic anemia. A peripheral blood smear showed macrocytes and hypersegmented neutrophils. Additionally, his serum vitamin B12 were markedly low. A microscopic stool examination revealed trapezoid shaped mature proglottids which are wider and long and contain a rosette shaped gravid uterus with a central uterine pore.