Answer to Case 234

Answer:  Earthworm

Given the larger size of this worm, Ascaris lumbricoides would be at the top of my differential.  However, note that this worm does not contain a thick acellular cuticle and a layer of tall circumferential muscle cells as would be expected for this nematode.  Instead, note that the outer cuticle is very thin and is underlain by tall epithelial cells containing mucin-producing cells. Below the epithelial layer are longitudinal and circumferential muscle cells, creating a thick muscular layer.

Finally, earthworms have a characteristic thickened band that is present near the anterior end of the worm called the clitellum.  Fortunately we were able to capture a cross-section through the clitellum as shown below.

Of course, this worm could have been most easily identified if it had been submitted to the microbiology lab immediately, before it was sectioned, fixed, and embedded.  I think Hans says it best with "Pathology, stay away from our worms!"

As to how this worm got into the boy's stool, I don't know if it was swallowed (would it survive the GI tract?  Any volunteers to find out?) or ended up in the stool after it was passed. 

Answer to Case 545

Answer: Not a human parasite: earthworm (Phylum Annelida, subclass Oligochaeta, Family Lumbricidae). It could very well be a Lumbricus species as some readers suggested, but I don't know enough about the different genera of earthworms to tell you for sure. Perhaps a knowledgeable reader can educate us on this topic?

So, wow, I've been on a roll with these parasite mimics! I'll try my best to include some true parasites in upcoming posts. Those of you who have followed this blog for a while probably know that I am fond of mimics - probably because they are so commonly seen in the clinical microbiology lab and provide an interesting challenge to clinicians, patients and laboratorians alike. In this case, I'm sure the patient wouldn't have hesitated to identify this object as an earthworm if it had been in a bait and tackle shop. It's when mimics end up in unfamilar settings (i.e., the toilet bowel) that they become a cause for alarm.

So how did this earthworm end up in the toilet? My plumber friend tells me that this is not an uncommon occurrence since pipes break due to the wear and tear of being in the ground. Tree roots, it would seem, are the enemy of sewage pipes.

For those of you wondering how to tell an earthworm apart from other large worms (e.g., Ascaris lumbricoides), here are some of the defining features that are not seen in human parasites:
1. Clitellum - the thickened glandular non-segmented portion of the earthworm's body found in sexually-mature adults.
2. Segmented body with setae. Setae are the small bristles found on each segment that help the worm move through soil.
3. A mucin-secreting epithelial layer beneath a thin cuticle. This is best appreciated on histopathologic exam; you can see a nice example in my previous CASE 234.

With that, I'll leave you with an interesting 'conversation' between two of our faithful readers, Old One and Florida Fan:

Florida Fan: "Hey Old One are you going fishing?". 
Old One: " Yeh". 
Florida Fan: " Got worms?" 
Old One: " Yeh, but I'm going fishing anyway."

And here is a poem from Blaine Mathison:
To see a worm wiggling in a toilet bowl
would certainly on anyone take its toll
but there's nothing to fear
for it didn't come out your rear
but a crack in your pipes allowed contamination from the soil!

For those of you who would like a more serious poem (with no offense to Blaine's), Florida Fan and Sir Galahad remind us of the poem by Jacques Roubaud, "Le lombric" (the Earthworm). You can find a passable translation HERE. Enjoy!

Case of the Week 234

A large "worm" (several cm in length) was passed in the stool of a 4-year old boy.  Unfortunately, rather than being submitted intact to the microbiology laboratory, it was sent to surgical pathology where slides containing serial cross-sections were produced.  Below are representative H&E images taken at 40 and 100 times original magnification:

Identification?

Answer to Case 605

 Answer to Parasite Case of the Week 605: Earthworm, an oligochaete. As a segmented annelid, these worms usually have a few setae (i.e., bristles) on their outer body surface, as seen in this case, which aid in their identification, and differentiation from large parasitic worms such as Ascaris lumbricoides.

As so nicely stated by Florida Fan, "Did we say “after the bowel movement”? Good thing the patient did not pass it out. Yes, we have seen this annelid a few times. (See Case 545, Case 344, and Case 234). It always shows the locomotive spicules on each ring of the body. A diligent, hardworking creature, it bores it tunnels through the rich loam most often ignored by most, it aerates its living Earth. Gardeners prize it for its urine and pellets, fisherman love it as their succulent wiggling bait irresistible to passing fish. Yet the humble night crawler got its place in French poetry in the poem “Le lombric’’. One time, I was formally complained to the medical director for signing the report as ‘’earth worm’’, the sample was referred to the State Laboratory where it was confirmed as being a Lumbricus terrestris. Yes this harmless worm can give a panic to a few caring parents. Well, long story short I should stop before being reprimanded for being ‘’Le Grand Bavard’’."

Don't worry Florida Fan - we will not accuse you of being a big talker, as we greatly appreciate your stories and descriptions!

Now to answer the question that one reader raised on Twitter - how did it get into the toilet? My plumber friend tells me that tree roots are the enemy of household pipes. Over time, the roots grow into pipes, leading to cracks and fissures through which our earth-living friends can enter. The video in this case can show how earthworms can be vigorous swimmers. They can easily swim 'upstream' to enter our toilets, and then be mistaken as a parasite of concern. 

So let's end with some levity, starting with the wonderful age-old joke from Old One:

 Florida Fan: "Hey Old One are you going fishing?". 

Old One: " Yeh". 

Florida Fan: " Got worms?" 

Old One: " Yeh, but I'm going fishing anyway."

And a poem from Blaine Mathison:

To see a worm wiggling in a toilet bowl

would certainly on anyone take its toll

but there's nothing to fear

for it didn't come out your rear

but a crack in your pipes allowed contamination from the soil!

For those of you who would like a more serious poem (with no offense to Blaine's), Florida Fan and Sir Galahad remind us of the poem by Jacques Roubaud, "Le lombric" (the Earthworm). You can find a passable translation HERE. 

Enjoy!

Answer to Case 344

Answer:  Earthworm, a segmented worm in the Annelida phylum.  As Hans pointed out, it has rings around its body and a "saddle" (clitellum) which is a sac in which eggs are deposited.

Thank you to Florida Fan for sharing your earthworm story. Another reader also wrote in with a comment on how often earthworms are submitted to the laboratory.  It's true! We get an earthworm submitted to our laboratory about once per week in the spring and summer months; (granted, we are a large reference lab and smaller labs probably don't see as many).

We've had several examples of annelids on this blog before:

Case 234 shows what an earthworm looks like on histologic sections (although sending intact worms to the microbiology lab is always preferred to sectioning them!)

and Case 254 is an example of medicinal leeches - another annelid.