Case of the Week 508

Happy Monday everyone! I'm on vacation this week, so here is a nice straight-forward identification for your viewing pleasure. A trichrome-stained stool specimen:

Images courtesy of Emily Fernholz. Identification?

Answer to Case 508

Answer: Giardia duodenalis, a.k.a. G. lamblia, G. intestinalis

As one of my twitter viewers comments - it's a Giardia party! Thus the inspiration for today's photo:

If you haven't done so already, I encourage you to read the posted comments from this case. They are very interesting and educational.

Case of the Week 507

This week's case was generously donated by Dr. Kamran Kadkhoda. The following was seen crawling out of the nostril of a young child from Southwest Asia. Identification?

Answer to Case 507

Answer: Male Pediculus humanus, likely P. h. capitis (clinical correlation required) - or - as Blaine and Florida Fan note - a booger bugger beastie!

As Idzi mentioned, it is not possible to tell P. h. humanus and P. h. capitis apart by morphology alone since there is significant overlap in sizes between the 2 otherwise identical subspecies.

Richard, Florida Fan and Idzi nicely discussed the likely route of introduction into the nostril: little fingers, or possibly even inhalation. It makes me wonder though - could the lice ever live on nostril hair? 

As a review, here are some of the key identifying features of Pediculus humanus:

• Small body (1-2 mm long)
• 6 legs 
• Dorsoventrally-flattened
• Wingless
• Raptorial (grasping) claws
• Fused thorax, distinct from the head (with antennae) and abdomen
• Enlongated body

Thanks again to Kamran for donating this case!

Case of the Week 506

This week's case is an arthropod removed from an elderly male living on the Pacific coast of the United States. He feels well and reports that he recently returned from safari in Tanzania.

Identification?
What infectious organisms are potentially transmitted by this arthropod?

Answer to Case 506

Answer: Hard tick, Hyalomma sp.

As many of you noted, this is one of the "Old World" ticks found in many parts of North Africa, South Africa, the Middle East, Asia, and Europe.

Here are a few important facts about this tick :

1. They are one of the most medically important ticks in the Old World. 
2. Important species include Hyalomma marginatum (Mediterranean Hyalomma), H. trucantum, H. asiaticum, H. excavatum, H. aegyptium, H. scupense and H. rufipes. 
3. They are vectors for several important disease agents, including Crimean-Congo hemorrhagic fever virus, several Rickettsia spp., Anaplasma phagocytophilum, Coxiella burnetii, and possibly Rift Valley Fever virus. 
4. They have also been implicated in human tick paralysis. 
5. Both female and male ticks bite humans and can transmit pathogens.
6. Compared to Ixodes ticks which climb vegetation and wait for a host to walk by, Hyalomma actively seek out their hosts (similar to Amblyommma spp.).
7. The tick is not endemic to North America, but there have been a series of case reports detailing imported Hyalomma species on humans, animals, and animal products. Check out the report that Blaine Mathison and I recently published HERE.

This is the second case of imported Hyalomma that has been brought to my attention in just the past 3 years, and the 3rd that Blaine has seen (!) highlighting the important of appropriate recognition and tick identification. 

As Blaine and I mention in our manuscript, Hyalomma spp. might be misidentified as Amblyomma when using keys for North American ticks. We state that "Hyalomma can best be separated from Amblyomma by having festoons of varying size, an inornate dorsal shield (scutum), and spurs on the coxae I roughly equal in length." Of note, many (but not all) Hyalomma spp. also have a striking band pattern on their legs as seen in this case.

Check out our manuscript for links to various regional-specific Hyalomma identification keys. Identifying the species can be tricky due to genetic variation and morphological variations.

Case of the Week 505

This week features our monthly case from Idzi Potters and the Institute of Tropical Medicine, Antwerp. The patient presented with a non-healing back furuncle shortly after returning from a trip to Bolivia. The following was removed from the furuncle:

Answer to Case 505

Answer: Dermatobia hominis, the human botfly

There are several helpful features in this case that allow for an identification to be made:

1. Overall "robust" and somewhat pear-shaped body with a narrow posterior.
2.  Large spines on all but the terminal 3 body segments
3. Supportive travel history (Bolivia)

We unfortunately don't have a view of the posterior respiratory spiracles which would have sealed the diagnosis, but the rest of the features are sufficient to call this D. hominis. You can look at a previous case to see what the spiracles would have looked like: Case of the Week 347. There is also a link there to an old, but still useful, key for identifying botfly larvae commonly seen in humans.

Please respond - 3 short survey questions!

All,
I’d like to hear from you regarding how you use my parasite case of the week blog for educating yourself or others. If you have time, please email me your answers to the following questions.
1. Do you look at the posts shortly after they come through, or do you save them for later? (feel free to elaborate)
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Thanks!
Bobbi