Tuesday, July 10, 2018

Case of the Week 501

This week's case features a zoonotic infection that can potentially involve humans. The patient is a sheep named Mr. Grumpy. Although grumpiness is his usual state of being, he was particularly grumpy when I saw him because he had a wound infested with maggots. Wounds in sheep can be difficult to detect early on because they are often hidden under dense wool. Poor Mr. Grumpy had likely acquired his wound while in a new pasture, and it had taken several days before behavior changes alerted the owners to his condition.

Here is the original photo of his wound (warning - not for the squeamish), followed by one after he has been shorn and cleaned up a bit:

Many thanks to Terri who allowed me to participate in removing the maggots from Mr. Grumpy and make him (hopefully) less grumpy. Harry (my student from London) and I plucked them one at a time from the wound and placed them in 70% ethanol for transport to the lab:




Here is a close up of the wool above the wound where a lot of the maggots were hiding:


Here they are some that were removed from the deep wound:


Once we were back in the lab, this is what we saw:



What is the identification of these maggots?

Here he is today - doing much better!



8 comments:

Blaine Mathison said...

Given the presentation and the posterior spiracles with: 1) incomplete peritreme, 2) lack of a defined button, 3) straight slits pointing to the opening of the peritreme, and 4) a lack of pigmented tracheae [at least they don't appear pigmented - would have been easier to confirm with a lighter background], I would have to say Cochliomyia macellaria.

William Sears said...

Spiracles not on knob, Incomplete peritreme, spiracular slits straight and pointing toward opening. Very light button (actually I can't see it at all). I would say Phormia regina or the black blow fly.
Who could watch this video and not fall in love with the beauty and romance of parasitology?

William Sears said...

I think I gave a baaaaaaaaad answer.......For the purity of the game, I will say that after reading blaine's post, I looked again and now I do see a protuberance at the end of a spiracular slit and so I think it is actually C macellaria and not phormia.

Blaine Mathison said...

Honestly William seeing additional images I am having doubts now, too. Although every time I run the images through various keys I keep coming back to C. macellaria.
Bobbi, if you have some alive, rear them to adulthood. That will resolve things nicely!

Bobbi Pritt said...

Great discussion and suggestion for rearing them! Unfortunately I've already killed them all off, and I think that Mr. Grumpy is all out of maggots :)

Jody Granberg said...

So I'm not super knowledgeable on parasitology but I find this immensely fascinating. My choice is P. regina

Anonymous said...

Now we have a debate of the Titans, I just sit around to watch and learn, though I do intend to go with Cochliomya sp.
Florida Fan

William Sears said...


The spines on the spiracular field are not super organized and now, upon further imaging, the protuberance on the spiracular slit has disappeared to my eyes. Also, there doesn't seem to be a thoracic spine V shape on the spiracular protuberance. All of these are point away from c masellaria. I would love to see a better button but c'est la vie.

I'm going back home to phormia regina, final answer.