Answer to Case 228

Answer:  Ova (eggs) of Paragonimus sp.

The identification can be made by the characteristic operculate eggs, moderate size (90-100 microns in length), thin shell, and lack of spines.  In some of the images, you can appreciate small "shoulders" or bumps on either side of the opercular opening, another characteristic feature of Paragonimus ova. 

Paragonimus westermani is the most common species worldwide to infect humans, but other species, such as P. kellicotti can infect humans as well.  It is not possible to tell the different species apart by the eggs alone, and therefore, the best identification is "Paragonimus sp."