CT: Linear high-density foci within dilated biliary tree

• Clonorchiasis: Flukes typically involve peripheral intrahepatic ducts, not GB, CBD, or PD
• Fascioliasis: Flukes usually involve large intrahepatic ducts, extrahepatic duct, and GB (after liver involvement)
• Echinococcosis: Communication of hepatic hydatid cyst with small biliary radicles or rupture of cyst into bile ducts






IMAGING
General Features
• Best diagnostic clue
CT Findings
• Ascariasis/clonorchiasis: Intraductal high-density foci within dilated biliary tree due to biliary worms/flukes or debris
MR Findings
• Clonorchiasis: Preferential peripheral biliary dilatation with low-signal filling defects on T2WI or MRCP
Ultrasonographic Findings
• Grayscale ultrasound
Ascariasis: Ultrasound very sensitive for worms in biliary system, but insensitive for worms in duodenum or ampulla (sensitivity for pancreatobiliary ascariasis only 50%)

DIFFERENTIAL DIAGNOSIS
Bacterial Cholangitis
Recurrent Pyogenic Cholangitis
• Disease associated with formation of pigment stones throughout biliary tree, as well as multiple biliary strictures and repeated bouts of cholangitis
PATHOLOGY
General Features
• Etiology
Clonorchiasis : Flukes ingested with uncooked freshwater fish → metacercariae excyst in duodenum → move to ampulla of Vater and ascend biliary tree

CLINICAL ISSUES
Presentation
Demographics
• Age
Ascariasis more common in children, but hepatobiliary involvement more common in adults (pediatric biliary tree may be too small for parasites to enter)
Clonorchis can colonize bile ducts for 25 years, and symptomatic infections are more common in older adults as disease burden can increase over time


Treatment
• Antihelminthic drugs are primary treatment: Praziquantel is moderately effective for clonorchiasis (20% cure rate with single dose), albendazole is very effective for ascariasis, and triclabendazole is very effective for fascioliasis




















