Acute infection is acquired by consuming watercress, water lettuce, or other greens contaminated with metacercariae (infective larvae form). The larvae excyst in the duodenum, migrate through the bowel wall into the peritoneal cavity, and penetrate the Glisson's capsule. The classic triad of the acute infection consists of hypereosinophilia, right upper quadrant pain (Murphy's sign), and fever, each of which is related to the migration of the larvae through the peritoneal cavity and liver. As the larvae migrate through the liver, they may cause severe damage to the liver, including subcapsular hematoma, hepatic rupture, multiple hepatic abscesses, and hepatic necrosis. Approximately 20%-25% of patients will experience urticaria and/or pruritus during the acute phase. The acute period of the disease lasts between 3 and 5 months. Finally, the larvae reach the large hepatic and common bile ducts.
The chronic stage develops when mature flukes reside in the bile ducts. Adult flukes produce eggs, and they reach the environment through the stools. The clinical picture of a chronic infection includes recurrent abdominal right upper quadrant pain, biliary colic pain (not associated with food), nausea, vomiting, recurrent or intermittent jaundice, and urticaria.
Some populations in endemic areas such as school-aged children, farmers, and vegetarians are at increased risk for acquiring the infection. Travelers may occasionally acquire the infection if they consume contaminated raw vegetables during a trip to endemic countries.
Liver fibrosis can occasionally occur in heavily infected patients or in those with comorbidities (hepatitis C, hepatitis B, alcohol use disorder, etc).
B66.3 – Fascioliasis
111922007 – Infection by Fasciola
- Acute cholecystitis – Usually presents without eosinophilia.
- Liver metastases – Lesions grow but typically do not migrate.
- Liver cysts – Asymptomatic without eosinophilia.
- Hydatidosis (echinococcosis) – Daughter cysts can be visualized by imaging; track-like lesions are absent.
- Amebiasis – Patient has septic, rounded liver lesions; there is an absence of serpiginous liver lesions.
- Ruptured hemangioma and subcapsular hematoma – Eosinophilia is absent; no travel history.
- Viral hepatitis (eg, HAV, HBV, HCV) – Jaundice is prominent, whereas in acute fascioliasis, jaundice is absent.
- Cholangiocarcinoma – Worsening jaundice; no recurrence.
- Pancreatitis – Increased amylase levels.
- Adult Ascaris causing biliary obstruction – Eosinophilia is absent. Cholangiogram can reveal a large wormlike structure in the bile duct, whereas Fasciola are rounded and small (3 cm long).
- Fasciola eggs can be confused with Paragonimus eggs (lung fluke), but the latter are mostly found in sputum specimens.