A 54-year-old man comes to the physician for a 3-week history of progressive difficulty with swallowing. His symptoms began with solids only, but have now progressed to liquids as well. Barium swallow shows an irregular mass at the gastroesophageal junction. Biopsy of the mass shows B-cell proliferation. Which of the following is the most likely explanation for these findings?
Clonorchis sinensis
Helicobacter pylori
Onchocerca volvulus
Paragonimus westermani
Schistosoma mansoni
