Monday, December 11, 2017

Case of the Week 472

This week's case features an intriguing video by Dr. Graham Hickling.

The accompanying questions are:
1. What arthropod is shown here
2. What stages of the arthropod are seen?

Sunday, December 10, 2017

Answer to Case 472

Answer: Hard tick (Ixodidae) nymph emerging from the larval exuvia. The inverted "U-shaped" anal groove on the ventral surface (photo below) allows us to identify this as an Ixodes species.
The gender is not possible to discern in nymphs, but as mentioned by Anon, it can be determined in adults by examining the scutum and basis capituli. The scutum (dorsal shield) of the female only covers a portion of the dorsal surface, compared to the male in which it covers nearly the entire dorsal surface. In the nymphal stage, both males and females have a similar-appearing scutum.  Also, only females have porose areas whereas males do not. The porose areas are located on either side of the basis capituli and produce antioxidants which are combined with waxy secretions from the Gene's organ. This substance is applied to eggs right after they are laid and serves as a protective coating. The porose areas also lubricate the Gene's organ, allowing it to expand and retract more easily.

Thanks again to Dr. Graham Hickling for donating this fascinating video. Thank you also to Dr. Robyn Nadolny for the additional information about the function of porose areas and Gene's organ. If you'd like to see the Gene's organ in action (and tick eggs being laid), check out this other amazing video by Graham.

Monday, December 4, 2017

Case of the Week 471

Welcome to the first case of the month featuring a case from Idzi Potters at the Institute of Tropical Medicine Antwerp. This case is really spectacular and something we don't see very often.

The following parasites were discovered in a man's peritoneal tissue during an inguinoscrotal hernia repair.  The resided in Benin, Africa. Here is the resected section of peritoneum along with the attached parasites (CLICK ON IMAGE TO ENLARGE):
 
Diagnosis?

Sunday, December 3, 2017

Answer to Case 471

Answer: Pentostomiasis; most consistent with Armillifer species. William Sears also suggested that Raillietiella sp. is also in the differential, which Idzi confirms. Both are found in African countries and associated with consumption of raw snake meat. Identification is accomplished morphologically by counting the annuli. You can also use molecular studies, although these are not widely available.

Idzi also provided me with the following beautiful (and very creepy) photos from his Institute's specimen archives which show an adult and larval Armillifer armillatus:

Idzi and his group published this case, so you can read more about it HERE. Fascinating case!