This week's case was generously donated from Drs. Cynthia Magro and Lars Westblade. The following object was identified in an hematoxylin and eosin stained tissue section of toenail in a patient with onychomycosis. Identification?
Monday, May 3, 2021
Welcome back to the first Monday of the month! It's time for our monthly case from Idzi Potters and the Institute of Tropical Medicine in Antwerp. The following structures were found in a stool specimen from a patient originally from the Democratic Republic of the Congo. He presented with long standing diarrhea (occasionally bloody), intermittent abdominal pain, decreased appetite and unintentional weight loss. They are approximately 200 micrometers long.
What is the most likely identification?
Sunday, May 2, 2021
Answer to Parasite Case of the Week 637: Schistosoma intercalatum
This was definitely a tricky case! The eggs strongly resemble those of Schistosoma haematobium, but stool would be an unusual source for this parasite, and the eggs in this case are larger than what would be expected for S. haematobium (usual size is 110 to 170 micrometers long). In comparison, S. intercalatum eggs are most often found in stool and measure 140 to 240 micrometers long. They also characteristically have an equatorial bulge as seen in one of the images from this case:
Of note, Schistosoma intercalatum has a very limited geographic distribution, being found primarily in the Congo area. Therefore, getting a travel history can be extremely helpful. As Marc Couturier pointed out on Twitter, the other major consideration is S. guineensis due to the morphologic similarities of the eggs of the two species. If a location had not been provided, then reporting out "Schistosoma intercalatum/S. guineensis" would be best.