Monday, January 25, 2021

Case of the Week 624

 This week's case is a bit unusual in that it is an environmental sample (but the parasite has relevance to human health). The following were seen in a soil sample taken from a child's playground. They are approximately 80 micrometers in greatest dimension. Most likely identification?


TheOracle said...
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TheOracle said...

From morphology, with the thick and corrugated shell, and dimensions I would say these are eggs of Toxocara canis, a possible agent of visceral larva migrans, neural larva migrans and ocular larva migrans, since larvae do not develop into adults in the human body. Eggs of T. cati should be a little smaller.

Italian new fan!

Ashton Drake Hall said...

I agree with the author above.

When I first read "playground," I thought about Baylisascaris procyonis and raccoon latrines. However, those eggs are typically darker and resemble Ascaris lumbricoides.

And hello Dr Pritt from a fellow LSHTM-er (Medical Microbiology)

Anonymous said...

Me too! I leaned over Baylisascaris procyonis because of the playground environment. Upon further examination especially with the corrugation of the egg shell, this corresponds more with Toxocara spp. The size of 80 nm is more consistent with Toxocara canis than T. cati.
Florida Fan

Old One said...

Agree with The Oracle and Florida Fan the eggs are from Toxocara sp. Both T. canis and T. cati have a protein coat with the pitted surface of a golf ball. You can see the texture most clearly where they are in focus around the edges of the eggs. Focus up and you can see the pitting on the rest of the egg. T. cati eggs (65-75um) are smaller than T. canis eggs (80-85 um). The pitting of T canis is larger and more distinctive than those found on T. cati eggs

Baylisascaris procyonis eggs superficially look like those of Toxocara, but their protein coat lacks the pitting found in the eggs of T. spp.

Size and surface morphology lead me to identify the eggs as Toxocara canis.

I suspect the leached color of the eggs may be an artifact of the preservative. Normally the fresh eggs of all 3 species is a rich dark brown.

Crespoo said...

I totally agree, this is Toxo sp. the egg is more spherical then that for A Lumbricoides. Also, just to say Toxo is anearobic right?

Bernardino Rocha said...

Agree with previous comments. Most likely eggs (Immature and mature egg containing an infectious larva)from T. canis.