Microscopy

Paragonimus westermani eggs range from 80 to 120 µm long by 45 to 70 µm wide.  They are yellow-brown, ovoid or elongate, with a thick shell, and often asymmetrical with one end slightly flattened.  At the large end, the operculum is clearly visible.  The opposite (abopercular) end is thickened.  The eggs are unembryonated when passed in sputum or feces.

A	B

A, B: Eggs of P. westermani in unstained wet mounts.

Paragonimus kellicotti eggs range from 80 to 100 µm long by 55 to 65 µm wide.  They are yellow-brown, ovoid or elongate, with a thick shell, and often asymmetrical with one end slightly flattened.  At the large end, the operculum is clearly visible.  The opposite (abopercular) end is thickened.  The eggs are unembryonated when passed in sputum or feces.

C	D

C, D: Eggs of P. kellicotti in a Pap-stained bronchial alveolar lavage (BAL) specimen.  Image C was taken at 400x magnification; Image D at 1000x oil magnification.  Images courtesy of Dr. Gary Procop.

E	F

E: Cross-section of an egg of P. kellicotti in a lung biopsy specimen, stained with periodic acid-Schiff (PAS) stain.  Image courtesy of Dr. Gary Procop.
F: Longitudinal section of an egg of P. kellicotti in a lung biopsy specimen, stained with hematoxylin and eosin (H&E).  Image courtesy of Dr. Gary Procop.

Adults of Paragonimus spp. are large, robust, ovoid flukes.  They are hermaphroditic, with a lobed ovary located anterior to two branching testes. Like all members of the Trematoda, they possess oral and ventral suckers.

G	H

G: Adult of P. westermani.
H: Adult of Paragonimus sp., taken from a lung biopsy specimen stained with H&E.  Note the presence of the oral sucker.  The species was not identified in this case.

I	J

I: Adult of P. kellicotti taken from a lung biopsy specimen stained with H&E.  This worm is in poor condition, indicating it was probably an old infection.  Image courtesy of Dr. Miguel Madariaga, University of Nebraska Medical Center.
J: Sections of several adults of P. kellicotti taken from a pleural biopsy stained with H&E.  Numbers 1-5 show the individual worms.  The integument is gone from most of the worms, as this was probably an old infection, but remnants of the gonad (A, dart) and uterine tubes (B) can be seen.  Image courtesy of Dr. Miguel Madariaga, University of Nebraska Medical Center.  Image first appeared in: Madariaga, MD, M. G., T. Ruma, MD, and J. H. Theis, MD. 2007. Autochthonous human paragonimiasis in North America. Wilderness & Environmental Medicine. 18(3): 203-205.  Image used with permission of © Allen Press Publishing Services.