Case of the Week 789

This week's case was donated by Dr. Blake Cirks. The following object was passed per rectum by an otherwise asymptomatic individual living in Laos. Based on the image and video, what is the most likely diagnosis?

Case of the Week 788

Happy Autumn, everyone! It's the first Monday of the month and time for our monthly case from Idzi Potters and the Institute of Tropical Medicine, Antwerp. The following were seen in a direct wet mount specimen of stool from a patient with chronic constipation. What is your identification?

Answer to Case 788

Answer to Parasite Case of the Week 788: Pentatrichomonas hominis trophozoites

Note the classic 'jerky' motility of P. hominis trophozoites. I've never seen so many P. hominis in a specimen before! 

Like Trichomonas vaginalis, there is no known cyst stage of this protozoan parasite. P. hominis trophozoites move using 5 flagella: 4 are directed anteriorly, while the 5th is directed posteriorly, forming the outer edge of an undulating membrane. This results in characteristic motility that Dr. Richard Bradbury likes to describe as "a man trapped inside a plastic bag"!  You can see a very nice video and still images of this phenomenon in Case of the Week 737. For those of you who have been following this blog since the beginning (2007!), you may recall that P. hominis was the parasite highlighted in Case of the Week 5. Check out the fun video that Alex Ball made for me back then in the Answer to the Case of the Week 5.

Thanks again to Idzi Potters and the Institute of Tropical Medicine Antwerp for donating this great case!