Case of the Week 347

The following object was submitted to my lab for identification as "removed from back." No travel history was given.

 

 

Identification? Thank you to Emily F. for these lovely photos.

Answer to Case 347

Answer:  Dermatobia hominis

Most of you recognized this as the 'human' bot fly, Dermatobia hominis, recognizable by its somewhat pear-shaped body, lack of spines on the anterior 3rd body segment, and posterior spiracle with 3 slightly-curved slits and a weak peritreme:

I believe that the bulging area on the body is a defect which occurred during removal, while the bubbles are likely due to the poor state of preservation of this specimen. Fortunately, the characteristic features are still apparent.

For those of you interested in learning how to identify the various myiasis-causing fly larvae in humans, the CDC has an old, but still relevant, manual on arthropod identification that you can access HERE.

Case of the Week 346

This week's case is in recognition of Lab Week, which is from April 19-25th. Many labs around the United States celebrate by having games, quizzes, and usually a potluck with lots of great food.

In order to share in the Lab Week fun, I thought I would share our quiz this year with you:

How many ticks are in this vial?

Answer to Case 346

Answer:  176 ticks!  They are all Ixodes scapularis in various stages of engorgement, although I didn't show you enough detail to identify them.

The winner is Olivier Levoux who has an interesting website devoted to ectoparasites.  Go check it out and encourage him to keep up the great work. His count was 153; only 23 less than the actual number, and not bad given that some of the ticks were probably clumped together in my photos. BKS is the runner up, with his guess of 203; only 27 ticks more than the actual number. (Olivier and BKS, as the winner and runner up, I would be happy to send you some ticks if you write to me with your address). 

I hope you all had a great lab week.

Case of the Week 345

This week's case came to my lab from a woman living in the upper midwestern US. As with many objects submitted for identification, this one came wrapped up in toilet paper. Thank you to Emily who took these lovely photographs.

Several eggs were expressed from this specimen that measured approximately 60 micrometers in length:

 

Identification?

Answer to Case 345

Answer:  Diphyllobothrium species (broad fish tapeworm)

The most common species found in the United States is Diphyllobothrium latum, although as Anon points out, there are other species of Diphyllobothrium (e.g. D. pacificum, D. ursi) that can also infect humans and they are essentially indistinguishable by morphologically alone. Therefore, it is best to simply identify these as "Diphyllobothrium sp."

This case is very characteristic of what we normally receive in the lab; that is, specimens that are not well-preserved and sometimes wrapped up in toilet paper or other materials. However, the characteristic features are still identifiable: proglottids that are wider than they are long with a central darkly-staining uterus and ovaries. As Florida Fan points out, the expressed eggs are also characteristic for this genus, with a clearly recognizable knobby protrusion (abopercular knob) and a less easily seen operculum.

Case of the Week 344

The following was submitted for identification.  The only history available was "found in diaper." Identification? Special thanks to Dr. Mike Mitchell who donated this case!

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.