Microbiology & infectious diseases
Parasites-gastrointestinal (not liver)
Macracanthorhynchus
Author: Nat Pernick, M.D.
Last author update: 17 June 2019
Last staff update: 5 October 2020
Copyright: 2019-2024, PathologyOutlines.com, Inc.
PubMed Search: Macracanthorhynchus
Table of Contents
Definition / general | Clinical features | Case reports | Gross description | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | VideosCite this page: Pernick N. Macracanthorhynchus. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/parasitologymacracanthorhynchus.html. Accessed December 26th, 2024.
Definition / general
- One of the Acanthocephala ("thorny headed worms")
Clinical features
- In humans, infection is most likely by M. hirudinaceus or M. ingens but the head of the worm is needed to morphologically identify this to the species level (Pritt: Creepy Dreadful Wonderful Parasites Blog - Answer to Case 540 [Accessed 17 June 2019])
Case reports
- A toddler passed a 15 cm long worm (Pritt: Creepy Dreadful Wonderful Parasites Blog - Case of the Week 527 [Accessed 30 September 2019])
- Objects were seen in a human stool specimen (Pritt: Creepy Dreadful Wonderful Parasites Blog - Case of the Week 540 [Accessed 17 June 2019])
Gross description
- Worms have a relatively large size (~15 cm)
- Constrictions give a false impression of segmentation, also known as a bubblegum appearance (Pritt: Creepy Dreadful Wonderful Parasites Blog - Answer to Case 527 [Accessed 30 September 2019])
- Retractable proboscis can be difficult to see; histologic sectioning may be needed
Gross images
Contributed by Bobbi Pritt, M.D.
15 cm long Macracanthorhynchus worm with pseudosegmented body and retracted proboscis
Microscopic (histologic) description
- Eggs are rare in human stool but are ovoid, 80 - 100 micrometers, dark brown with a thick rugged textured shell (Pritt: Creepy Dreadful Wonderful Parasites Blog - Answer to Case 540 [Accessed 17 June 2019])
- Within the egg is the characteristic larval form (acanthor) with rostellar hooks
- Histologic sectioning of anterior end of worm can show retracted proboscis (Pritt: Creepy Dreadful Wonderful Parasites Blog - Case of the Week 527 [Accessed 30 September 2019])
Microscopic (histologic) images
Contributed by Bobbi Pritt, M.D. and Emily Fernholz
Macracanthorhynchus eggs
Histologic sections of anterior end of Macracanthorhynchus worm
Videos
Macracanthorhynchus egg
