Answer to Case 793

Answer to the Parasite Case of the Week 793: Strongyloides stercoralis L3 (filariform) larvae

This case shows the classic features of the L3 larvae with a blunt-ended (and subtly-notched) tail. 

Some of you noted the shorter larva as well, which is reminiscent of an L1 larva. However, this would be unlikely given the lifecycle of S. stercoralis. 

I also considered if this could be an L4 larva, given Dr. Richard Bradbury's excellent 2024 JCM publication. However, these rarely-seen L4 larvae have a pointed or cone-shaped tail rather than a blunt, notched tail.

The number of larvae and the host's immunocompromised state are concerning for hyperinfection syndrome. When we see one of these cases in my lab, we immediately call the patient's primary care team to alert them. 

Thanks again to Dr. Linoj Samuel for donating this great case!