Morphological examination of biopsy reveals infection is sparganosis. (A) A 1.6-fold magnified view of the worm and adjacent brain tissue from biopsy; the worm is unsegmented (although there are infoldings of the cuticle), without intestine, and uniform in internal structure. (B) A host granulomatous reaction featuring focal necrosis, epithelioid and multi-nucleated giant cells of macrophage-derivation, some plasma cells and lymphocytes but no eosinophils that, considered in isolation, resembles tuberculosis (×20). (C) A 20-fold magnified view of the worm demonstrates the eosinophilic syncytial tegument, sub-tegumental nuclear layer, and the internal watery stroma that includes thin muscle fibres, round cells, and ‘empty’ tubular excretory ducts. (D) A 40-fold magnified view of the internal stroma exhibits thin eosinophilic muscle fibres and stromal cells with pale haematoxyphilic cytoplasm. All images stained with haematoxylin and eosin and scale bars are 5 mm (A), 0.5 mm (B,C) and 0.25 mm (D).