Case #216 – November, 2007

An asymptomatic, 35-year-old male with no known travel history went to his physician at a wellness clinic for a routine examination. An ova and parasite (O & P) examination was performed as part of the laboratory work-up at the State Health Laboratory. Unusual objects were observed in the formalin-concentrated stool, and the specimen was sent to CDC for diagnostic assistance and possible identification. Figures A-D were captured from wet mounts of the specimen. The objects measured approximately 50 micrometers by 42.5 micrometers. What is your diagnosis? Based on what criteria?

Figure A

Figure B

Figure C

Figure D

The objects were artifacts, most likely pollen grains, and a diagnosis was made of No Parasites Found (NPF). They closely resemble the fertile eggs of Ascaris lumbricoides. However, the size was not consistent with A. lumbricoides eggs (usually 55-75 micrometers by 35-50 micrometers) and the objects had pointed spines on the exterior, whereas fertile A. lumbricoides eggs have rounded mamillations.