Answer to Case 608

 Answer to theParasite Case of the Week 608:Taeniasp. egg. The eggs are those of T. solium, T. saginata,orT. asiatica, but it is not possible to tell the species from the egg alone. You can find more informations about these interesting cestodes on the CDC ' sDPDx website.Note the classic small size (30-35 micrometers in diameter) of the eggs. Each have a thick radially-striated outer wall and internal 6-hooked oncosphere. The hooks aren ' t easily visible with H&E, but they are refractile when viewed with a narrowed condenser. It is likely that the eggs were released from a mature gravid proglottid in the large intestine and made their way into an ulcerated region of the mucosa where they were an incidental finding on biopsy.Taenia soliumandT. saginatado not invade the mucosa (other than at the point where the hooklets anchor the adult worm ' s scolex to the small intestine), so there must have been some other condition present that caused the intestinal disruption in this patient.Some readers commented that this could also beEchinococcussp. if this was a canid rather than a human host.Echinococcusspp. adults are found within the canid definitive host and the eggs are shed into the environment where they are ingested by herbivore intermediate hosts. Humans are accidental intermediate hosts. After ingesting the eggs from the environment, the eggs hatch in the small intestine to release the oncosphere. Thus we wouldn ' t expect to see intactEchinoc...
Source: Creepy Dreadful Wonderful Parasites - Category: Parasitology Source Type: blogs