Sunday, December 16, 2018

Answer to Case 523

Answer: Acanthamoeba sp. cysts and trophozoite.

Wow, I really enjoyed reading the comments on this case! If you haven't already, I encourage you all to ready the holiday tale of Ascaris suum (a.k.a. Ascaris lumbricoides) by Old One. The story confirmed my suspicions of why we see so many cases of human ascariasis in patients from the Midwestern United States who haven't traveled internationally. The pigs are loaded with them!

The comments also nicely describe the differences between the cysts and trophozoites of the free-living amebae that most commonly cause human disease: Acanthamoeba species, Balamuthia mandrillaris, and Naegleria fowleri. Therefore I won't describe them further here. However I will show you some of the main discernible features from the transmission electron micrographic images in this case:


Carlo Alberto Varlani said...

Grazie! Bellissimo caso. :-) Buon Natale, Bobbi :-)

Blaine A. Mathison said...

I think you mean Ascaris lumbricoides (AKA A. suum) - A. suum is no longer considered a valid species ;-) Actually, it really hasn't for over 100 years! The veterinarian community just won't accept the change!

Old One said...

As a veterinary parasitologist, I agree with Blaine.

Old One said...

I probably should elaborate on my last comment. My mentor actually infected himself with pig ascarid eggs. He passed only a single adult worm. It remained in a jar of ethanol until his retirement. I don't think his wife let hm take it home.

The story passed by vet. parasitologists was that human infections from a proven pig source generally resulted in few worms while infections from a human source often had huge worm loads. This is mostly hearsay to me, perhaps someone can illuminate the old one.

All this ascarid talk reminds me of another tail.

A lion researcher from our university was traveling by train in Tanzania. There was a mother and child siting across from him. At one point during the trip the child leaned over and vomited a copious amount of ascarids on the lap of the researcher then promptly died.

I've always held that the human and pig ascarids were the same species but they are in an early stage of species divergence but not quite there.