Microscopy

Sparganosis is infection by the third-stage plerocercoid larva (sparganum) of pseudophyllidean cestodes of the genera Spirometra and Sparganum, the latter of which may be an aberrant Spirometra sp.  The definitive hosts for Spirometra spp. are canids and felids, and humans serve as only paratenic or second intermediate hosts for the parasites.  Spargana can be found in many organs in the human host, including the pleural cavity, eyes, pericardium, abdominal cavity and viscera, and the central nervous system.

A	B

A, B:  Proliferating spargana in groin tissue of a patient from Paraguay, stained with hematoxylin and eosin (H&E).

C	D

C: Proliferating sparganum in lung tissue in a patient from Taiwan, stained with hematoxylin and eosin (H&E).
D: Higher magnification of the sparganum in Figure C.  In this image, calcareous corpuscles (green arrows) can be seen.

E	F

E: Sparganum removed from the chest wall of a patient.  The worm measured about 70 mm long.  Image from a specimen courtesy of the Oklahoma State Department of Health.
F: Sparganum removed from the ocular conjunctiva of a patient from Taiwan.  The worm measured 40 mm long.  Image courtesy of Dr. John H. Cross and the Uniformed Services University of the Health Sciences, Bethesda, MD.