Microbiology & infectious diseases
Parasites-hepatobiliary
Fasciola
Author: Elliot Weisenberg, M.D.
Last author update: 1 August 2015
Last staff update: 6 October 2020
Copyright: 2003-2025, PathologyOutlines.com, Inc.
PubMed Search: Fasciola [title] colon
Table of Contents
Definition / general | Epidemiology | Etiology | Diagrams / tables | Clinical features | Diagnosis | Case reports | Treatment | Gross description | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Differential diagnosis | Additional referencesCite this page: Weisenberg E. Fasciola. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/colonfasciola.html. Accessed January 8th, 2025.
Definition / general
- Disease of the intestine caused by infection by the trematode (liver fluke) Fasciola hepatica
- Infection by F. gigantica is often included in this category
Epidemiology
- Disease is more common in animals; however, worldwide an estimated 2 million people are infected
- Disease is uncommon in the continental United States and Canada
- Disease is more common in Europe, Asia, Africa, the Caribbean, and South America
- The highest rates of infection are in Bolivia and Peru in the Andean highlands
- Disease has been reported in Hawaii
- Infection may be endemic or imported
- Disease related to infection of the colon is very rare
Etiology
- Life cycle:
- Adult hermaphroditic worms in mammalian bile ducts, usually sheep or cattle, pass immature eggs in feces in fresh water
- The eggs hatch releasing miracidium that infect Lymnaeidae snail hosts
- In 5 to 7 weeks the snails release cercariae that lose their tails and become metacercariae with a hard outer cyst wall that attach to plants and can survive for long periods
- Cysts may also float on water
- Human disease is relatively commonly caused by ingestion of raw watercress
- The plants are eaten by cattle, sheep, or people
- The metacercariae hatch in the duodenum, penetrate the intestinal wall, and migrate across the peritoneum to the liver
- They burrow into the liver for 2-3 months, mature into adults, and enter bile ducts completing the cycle
- Worms may live 10 years in bile ducts
- Uncommonly, infection has occurred from ingestion of undercooked goat or sheep liver
Diagrams / tables
Images hosted on other servers:
Life cycle
Clinical features
- Acute or invasive fascioloidiasis generally causes right upper quadrant pain and discomfort, fever, hepatomegaly, and eosinophilia
- Less commonly immune mediated disease of the heart, lungs, or nervous system may occur
- Chronic disease is associated with chronic biliary obstruction, ascending cholangitis, and jaundice
- In contrast to acute disease, eosinophilia may be mild or absent
- Cirrhosis or malignancy may ensue. Disease caused by ectopic flukes is uncommon, it has been reported in subcutaneous tissue, lymph nodes, epididymis, duodenum, appendix, stomach and colon
- Only rare case reports of colonic disease exist - these patients have presented with abdominal pain and right sided colon masses
Diagnosis
- In general, diagnosis is from identification of eggs in stool although serologic testing exists
- In colonic cases the diagnosis has been made from identification of worms and eggs during tissue examination
Case reports
- 19 year old woman with ectopic fascioliasis (Kisaengchunghak Chapchi 1982;20:191)
- 27 year old woman with human ectopic fascioliasis in the cecum (Am J Surg Pathol 1984;8:73)
- 55 year old man with ectopic fascioliasis mimicking a colon tumor (World J Gastroenterol 2007;13:2633)
Treatment
- Triclabendazole, available through the CDC under a special investigational protocol
- Resistance has been reported (Emerg Infect Dis 2012;18:1028)
Gross description
- In the colon, masses mimicking malignancy are described
- Mechanical bowel obstruction has been reported
- In bile ducts, the adult worm is leaf shaped and up to 2 cm in greatest dimension
Gross images
Images hosted on other servers:
Adult liver fluke
Microscopic (histologic) description
- In the colon sinus tracts, eosinophilia, Charcot Leyden crystals, necrosis, fibrosis, granulomatous inflammation, lymphocytic and plasma cell infiltrates
Microscopic (histologic) images
Images hosted on other servers:
Egg with unshouldered operculum
Differential diagnosis
- In the liver depending on the circumstance the differential diagnosis includes ascending cholangitis, cysts caused by bile duct dilation caused by other infections (other fasciola, clonorchiasis), non-paracytic cysts, primary biliary cirrhosis, and sarcoidosis
- During parasitic exam F. hepatica must be distinguished from F. buski
Additional references
- CDC - Fascioliasis, Travel Med Infect Dis 2014;12:636, Clin Infect Dis 2001;33:1, Emerg Infect Dis 2005;11:1507, Clin Microbiol Rev 2009;22:466, Kradin: Diagnostic Pathology of Infectious Disease, 1st Edition, Bennett: Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 2nd Edition
