Case #329 – August, 2012

A seven-year-old boy had an ova-and-parasite (O&P) stool examination performed as part of a required refugee screening. Laboratorians at the state health department observed what they believed to be a few eggs within the size range of 110-120 micrometers. A trematode infection was suspected and images of the eggs were captured and submitted to DPDx for diagnostic assistance. The DPDx team requested that an aliquot of the concentrate be sent for further examination. Figures A–D show what was observed at 200x magnification. The objects of interest measured 115 x 72 micrometers on average. What is your diagnosis? Based on what criteria?

Figure A

Figure B

Figure C

Figure D

This was a case of echinostomiasis caused by a trematode in the genus Echinostoma. Morphologic features shown in the images included:

eggs within the size range for Echinostoma spp. (80-135 micrometers long by 55-80. micrometers wide), ruling out those of Fasciola and Fasciolopsis, which are both larger (130-150 micrometers long by 60-90 micrometers wide).
presence of an inconspicuous operculum (Figures A and C).
thickening of the abopercular end (Figure C).