Most patients with a fish tapeworm (Diphyllobothrium latum) are asymptomatic. Some patients may have symptoms, especially if comorbid conditions such as malnutrition are present.


Clinical findings:

(1) vague abdominal discomfort

(2) pallor and fatigue (due to anemia)

(3) diarrhea

(4) headache

(5) malaise

(6) dizziness

(7) neuropsychiatric complications of vitamin B12 deficiency (rare)

(8) change in appetite (may be increased or decreased)

(9) mechanical bowel obstruction

(10) vomiting or defecating several proglottids or a whole worm


Laboratory findings

(1) mild eosinophilia

(2) macrocytic anemia ("tapeworm anemia") secondary to vitamin B12 deficiency

(3) decreased serum vitamin B12


Often the infection is found incidentally when the patient is being worked up for another problem.


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