Answer to Case 696

 Answer to the Parasite Case of the Week 696:  Schistosoma haematobium egg and larva (miracidium).

As noted by Florida Fan, the morphology of the eggs is consistent with S. haematobium and S. intercalatum, as both are ovoid with a terminal spine. However, S. haematobium is usually found in urine, whereas S. intercalatum is usually found in stool. I didn't provide a size in this case, but it's helpful to know that S. intercalatum is also usually longer than S. haematobium and has a central bulge.

It is unusual to see a free miracidium in the urine. Note the circumferential cilia which gives it a shaggy appearance. 

TheOracle and Idzi mentioned that the presence of the free miracidium suggests a delay between sample collection and microscopic evaluation without preservation. Hatching of Schistosoma eggs can also be triggered by dilution of the specimen in water. Idzi had previously donated a beautiful case of a motile miracidium to this blog, which you can see HERE. Look how fast it is! This miracidium was also initially moving, but had stopped by the time we attempted to take a video. Thanks again to Felicity Norrie for these beautiful photographs!