Monday, September 16, 2013

Answer to Case 274

Answer:  Ascaris lumbricoides

Although I didn't show you a close up of the worms in this surgical container, the size and gross morphology are most consistent with the large nematode Ascaris lumbricoides.  Small bowel obstruction is a dreaded complication of Ascaris infection, made possible by the large size of the worms and smaller diameter of the small bowel.  Hans found a link to a very interesting (and somewhat disturbing) YouTube video of a surgery for obstruction due to ascariasis:

BHS mentions that Ascaris suum could also be in the differential if the patient has exposure to pigs.  This brings up an interesting conundrum.  The genomic and proteomic profiles of A. lumbricoides and A. suum are nearly identical and some argue that the two species actually represent a single organism.  However, like the head and body louse, the 2 organisms seem to have different ecological niches, and it is therefore hard to argue that there are no significant differences between them.  Fortunately the treatment is the same regardless of the species identification.

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