It's the first Monday of the month, and time for another great case by Idzi Potters and the Institute of Tropical Medicine, Antwerp, Belgium!
The following object was found in a soil sample from a child's playground. It is approximately 80 micrometers in largest dimension.
This week's case was donated by Heather Morris, the parasitology lead in my laboratory. We received the following objects for identification:
This week's case features two ~1 cm long tan-white worms removed from the terminal ileum during routine colonoscopy. What is your identification?
Anterior end:
Posterior end - worm one:
Answer to the Parasite Case of the Week 812: Adult hookworms, male and female.
As noted by Idzi Potters and Florida Fan, it's a bit hard to make out the mouth parts from the first photo. However, by focusing up and down on the actual clinical specimen, we were able to confirm that there are 2 pairs of teeth present, consistent with Ancylostoma duodenale. The second image shows the end of the female worm, whereas Idzi notes that the third "gives a nice view of the bursa copulatrix - a specialized organ found in male hookworms, used for sensing and grasping during copulation." The spicules at the end of the male do not appear to be fused, which supports the identification of A. duodenale.
Florida Fan noted that "The images may be sufficient for treatment but for academic purposes they pose a challenge. Would a stool parasitology culture help to identify the species involved?" This is a great question. If eggs are present in the stool, they could be hatched using the Harada Mori or similar culture method, and this would allow them to develop into L1 and eventually L3 larvae. There are some subtle differences between the L3 larvae of the different hookworm species, so it might be possible to differentiate them from the L3 stage alone. However, I'm not sure I would be able to accurately differentiate them. Unfortunately, this is where the life cycle stops for stool culture; we can't rear the larvae into adults, since this requires entry into a suitable host. Thank you for bringing up this option, Florida Fan!
This week's case was donated by Dr. Francesca (Frankie) Lee. The following images are from Gram-stained and wet prep slides of a BAL from an immunocompromised patient.
Answer to the Parasite Case of the Week 811: Strongyloides stercoralis L3 larvae; presentation consistent with hyperinfection.
As noted by Florida Fan, this is a "typical case of full blown invasive strongyloidiasis. The Gram stain didn’t give us much detail for the identification. The wet mounts appear to show the notched tail of the infective filariform stage."
Here is a closer up view of the notched tail from Dr. Lee, confirming the identification of S. stercoralis L3 larvae:
Florida Fan also shared that while the "filariform larvae cannot penetrate nitrile examination gloves, I would surely take extra precautions while handling such a specimen such as double gloves." HLCM Fan also shared a story of a past case: " We had a case of S. stercoralis a years back and went a little crazy with lab security measures (double gloves, nobody could use the BSC after us before we clean it with alcohol and UV, biosafety apron with sleeves, the samples were inactivated before leaving the lab, etc). We were not exaggerating; this sample is really dangerous."
These precautions are important as L3 larvae can penetrate intact skin and cause infection in the human host. In addition to glove use, we would tape up the bacteriology culture plates to prevent the larvae from migrating outwards.
HLCM Fan asked how we can differentiate the larvae in this case from those of S. fuelleborni. Fortunately, the answer is simple: S. fuelleborni does not have an autoinfection cycle, so we would not expect to find L3 larvae in a respiratory specimen during the chronic stage of infection. It is only during the early acute stage that the larvae may migrate through the lungs before reaching the intestinal tract (see the CDC lifecycle).
Thanks again to Dr. Frankie Lee for donating this classic case!
This week's case features some immature insects submitted in a sterile collection cup with balled up tissues inside. The patient is a middle-aged female, and no source or clinical information is provided 🫤.
Looking closely, 3 tiny brown specs ~ 1mm in size could be seen through the cup using the dissecting microscope. Our lab staff are rightly cautious about opening containers when tissue or other material obscures the contents in case there is something alive and/or contagious inside!
Answer to the Parasite Case of the Week 810: Pediculus humanus (head and body louse) nymphs
As noted by Richard Pollack, these are Pediculus nymphs. As he succinctly put it, "If from the scalp, they're head lice. If from the body or clothing, body lice."
Unfortunately, as is often the case, we did not receive any clinical history. There were also no clues from the specimen itself—such as attached nits on hair shafts—or information regarding the collection site that would allow us to distinguish between head lice (Pediculus humanus capitis) and body lice (Pediculus humanus humanus).
Several readers commented on the prominent eyes of the immature lice. This is a feature commonly seen in juvenile animals, where the eyes appear disproportionately large relative to the rest of the body. These early-stage lice (nymphs) are no exception. In fact, their oversized eyes and compact bodies give them a surprisingly "cute" appearance—at least from my perspective, recognizing that not everyone shares the same enthusiasm for parasites!
Of course, these youngsters are already equipped with the claws and mouthparts needed to begin life as obligate human ectoparasites. Cute is definitely in the eye of the beholder.
