Answer to Case 587

Answer to Parasite Case of the Week 587: Balantioides (formerly Balantidium, Neobalantidium) coli. Note the characteristic circumferential cilia and large "kidney bean" shaped macronucleus:

I was impressed by how many people knew about the complicated taxonomy of this organism. Blaine Mathison and I had published on Neobalantidium coli in our Medical Parasitology Taxonomy Update (J Clin Microbiol. 2019;57:e01067-18) only to discover shortly afterwards that Balantioides has priority over Neobalantidium (we are now working on a correction). From our research, we discovered that Alexeieff was the first to describe Balantioides to accommodate B. coli in 1931. Unfortunately this French manuscript went largely unnoticed for decades, and Pomajbikova et al. alternatively described Neobalantidium in 2013 to accommodate B. coli. We can credit Pomajbikova and Stensvold for later uncovering the 1931 manuscript for us and shedding light on current state of taxonomy of Balantioides coli.

I have a pdf of the 1931 French manuscript (with my own translation) if anyone is interested in it. I should note that my French is very rusty, so there may be some errors! Just send me a message at b_pritt@yahoo.com if you would like a copy.

I'd also encourage you to read all of the interesting comments from this case. There are a lot of great pearls in there.