Biliary Parasitic Infections

Common Parasitic Infections:

Feature	Fasciola	Clonorchis sinensis
Common Name	Common or Sheep liver fluke	Oriental or Chinese liver fluke
Intermediate Host	One = SNAIL	Two = SNAIL ⇒ FISH/CRAB
Transmission	Ingesting vegetables	Ingesting fish
Entry/Path	Penetrates Glisson's capsule	Travels through ampulla
Preferred Bile Duct	Prefers Extrahepatic Bile Duct (EHBD)	Prefers Intrahepatic Bile Duct (IHBD)
Lifespan in Host	10-14 years	Up to 45 years
Associated Diseases	Liver fibrosis, Cholangiocarcinoma (CCA)
[No association with HCC]	Cholangiocarcinoma (CCA), Hepatocellular Carcinoma (HCC)
Treatment	Triclabendazole	Praziquantel
[Does not Respond to ALBENDAZOLE]

Difference between two parasites: • Fasciola - single intermediate • Fasciola- vegetarians • Fasciola- direct invasion of liver

Fascioliasis Overview

• Fascioliasis is a zoonotic disease caused by Fasciola hepatica and Fasciola gigantica. These parasites are liver flukes primarily affecting domestic and wild ruminants but can infect humans. F. hepatica is commonly found in temperate zones, whereas F. gigantica is prevalent in tropical regions.

Epidemiology

• Fascioliasis is globally distributed and particularly common in sheep- and cattle-raising areas.
• Human Infections: Estimated between 35 to 72 million globally, with 180 million at risk. The Andean region in South America is highly affected, with prevalence rates ranging from 6% to 68%.
• Transmission Patterns: Four proposed patterns include imported cases, autochthonous isolated cases, endemic fascioliasis, and epidemic fascioliasis.

Life Cycle

• The life cycle begins with the release of eggs in stool, which hatch in water, and the miracidia infect freshwater snails. The larvae leave the snail, become free-swimming cercariae, attach to water plants, and encyst. Humans ingest the metacercariae by eating contaminated plants or water.
• In Human Hosts: The larvae migrate from the intestine to the liver, eventually residing in the bile ducts where they can live for years, producing eggs that continue the cycle.

Risk Factors

• Consumption of contaminated raw vegetables like watercress, lettuce, and alfalfa is the primary source of infection. Drinking contaminated water is another significant risk factor.
• Epidemiologic Studies: Show a strong correlation between alimentary habits, proximity to irrigation channels, and fascioliasis, particularly in endemic areas.

Clinical Manifestations

Fascioliasis has two distinct phases: Acute and Chronic.

Acute Infection

• Occurs within the first 3 to 5 months of infection as the larvae migrate through the liver. Symptoms include fever, hepatomegaly, abdominal pain, and significant eosinophilia. Imaging may show multiple hepatic lesions, often confused with metastases.

Chronic Infection

• Begins 3 to 6 months after infection as the parasite resides in the bile ducts. Symptoms include biliary obstruction, colicky pain, and sometimes asymptomatic cholestasis. Imaging may show biliary duct changes and liver fibrosis.

Imaging Studies

• Ultrasound (US): Often used but has low sensitivity, especially in chronic cases.
• Computed Tomography (CT): More effective, showing hepatic lesions, subcapsular hematomas, and calcifications in chronic cases.
• Magnetic Resonance Imaging (MRI): Limited cases reported, with findings similar to CT, but with better soft tissue contrast.

Diagnosis

• Acute Phase: Enzyme-linked immunosorbent assay (ELISA) is the most sensitive test.
• Chronic Phase: Diagnosis is typically confirmed by finding eggs in stool, bile, or duodenal aspirates. Repeated stool examinations and sedimentation techniques can improve detection rates.

Treatment

• Triclabendazole is the treatment of choice, effective in both acute and chronic phases with a high cure rate. Resistance has been reported in animals and, to a lesser extent, in humans.
• Other treatments include bithionol and nitazoxanide, although they are less effective.

Future Directions and Vaccines

• Ongoing research aims to develop vaccines, particularly targeting livestock to reduce the economic impact of the disease. Vaccines targeting cysteine proteinases and glutathione transferases show promise in animal models.

Risk Factors for Fasciolosis: Identifying the Least Likely Group

Non-vegetarians (b) who do not consume contaminated plants are less likely to be at risk of fasciolosis.

Explanation:

• Female (a): Women have been found to have a higher prevalence of fasciolosis, with more severe infections and liver or biliary complications.
• Non-Vegetarians (b): Fascioliasis is mainly contracted through the ingestion of contaminated water or plants like watercress and alfalfa. While non-vegetarians can consume these plants, the primary risk is associated with consuming raw or undercooked contaminated vegetation, not necessarily meat, making this the correct answer.
• Alfa alfa juice and salads intake (c): These are significant risk factors because they are common sources of contaminated plants that harbor the Fasciola larvae.
• Living close to canals (d): This is a risk factor because canals can harbor the intermediate snail hosts that contribute to the transmission of Fasciola.

Clonorchiasis and Opisthorchiasis: An Overview

Epidemiology

• Liver fluke infections caused by Opisthorchis viverrini, Opisthorchis felineus, and Clonorchis sinensis are significant public health concerns in the Far East, Southeast Asia, and Eastern Europe.
• Clonorchis sinensis is prevalent in northeast China, southern Korea, Japan, Taiwan, northern Vietnam, and Russia.
• Opisthorchis viverrini is primarily found in Laos, Thailand, Vietnam, and Cambodia.
• Opisthorchis felineus is most common in Russia, Ukraine, and Kazakhstan.
• Over 35 million people are infected globally, with 15 million Chinese and 10 million infected with O. viverrini.

Life Cycle

• Adult worms deposit fully developed eggs in humans, which are then passed through feces into water, where they hatch and infect freshwater snails.
• Opisthorchis and Clonorchis share a similar life cycle, involving the infection of fish as the second intermediate host.
• The parasites migrate to the human liver via the bile ducts and mature into adult worms within 4 weeks, living for up to 45 years and producing thousands of eggs daily.

Clinical Manifestations

• Most individuals are asymptomatic. When symptoms do occur, they include right upper quadrant pain, flatulence, and fatigue.
• Clonorchiasis can cause pyogenic liver cholangitis, cholecystitis, obstructive jaundice, and in severe cases, cholangiocarcinoma.
• Opisthorchis viverrini can lead to chronic hepatomegaly, intrahepatic duct stones, recurrent suppurative cholangitis, and cholangiocarcinoma.
• Opisthorchis felineus infection typically presents with more acute symptoms like fever, anorexia, and abdominal pain, and chronic infection can lead to cholangitis and liver abscesses.

Consequences of Chronic Infection

• Chronic infection with C. sinensis and O. viverrini can cause bile duct obstruction, fatigue, abdominal discomfort, and more severe complications like cholangitis, cholangiohepatitis, and cholangiocarcinoma.
• Cholangiocarcinoma is a significant risk, particularly with O. viverrini due to the secretion of parasite proteins that promote tumorigenesis.
• Gallbladder can become nonfunctional and enlarged, and dead parasites can serve as a nidus for stone formation.

Diagnosis

• Serologic tests such as the Ov-CP-1–based ELISA are helpful for diagnosis, though they may not distinguish between recent or past infections.
• Human clonorchiasis and opisthorchiasis are primarily diagnosed by detecting eggs in feces using the Kato-Katz method.
• Imaging findings include intrahepatic duct dilatation and increased periductal echogenicity.

Treatment

• Praziquantel is the drug of choice, with a high cure rate for both O. viverrini and C. sinensis.
• Tribendimidine and Albendazole are alternative treatments, particularly in areas where praziquantel resistance might develop.
• Combination therapy with praziquantel and triclabendazole is recommended in areas with both Fasciola and Clonorchis infections.

Other Parasitic Infections of the Biliary Tract

1. Ascaris lumbricoides (Ascariasis)

• Description:

  • Ascaris lumbricoides is the largest intestinal nematode parasitizing humans, with females measuring 25 to 35 cm in length.
  • Doesnot require intermediate host
  • Infections are endemic in tropical and subtropical regions, particularly where sanitation is poor, and human feces are used as fertilizer.
  • The parasite can occasionally migrate from its normal habitat in the small intestine to the biliary tract or pancreatic duct.

  

• Clinical Manifestations:

  • Ascariasis can cause biliary colic, jaundice, and fever due to the obstruction of the biliary tract by adult worms.
  • Complications include biliary obstruction, cholangitis, pancreatitis, and, in severe cases, ileal volvulus, perforations, intussusception, and impacted worm boluses.
  • ERCP (Endoscopic Retrograde Cholangiopancreatography) can be used to diagnose and treat biliary ascariasis by removing the worms.
• Treatment:
  • Following ERCP for the removal of the worms, a single oral dose of Albendazole (400 mg) is recommended to eliminate any remaining parasites.

2. Echinococcus granulosus (Hydatid Disease)

• Description:
  • The larval cystic stage of the tapeworm Echinococcus granulosus causes hydatid disease, which can affect various organs, including the liver.
  • Hepatic hydatid cysts can rupture into the biliary tree, leading to biliary obstruction.
• Clinical Manifestations:
  • The rupture of a hepatic hydatid cyst into the biliary tree can cause cholangitis, biliary obstruction, and, in some cases, anaphylaxis due to the release of cyst contents.
  • ERCP plays a crucial role in managing biliary complications of hydatid disease by removing hydatid membranes and debris from the biliary tract.
• Treatment:
  • Before any endoscopic or surgical intervention, oral Albendazole (400 mg) twice daily should be administered to inactivate intracystic material and minimize the risk of postoperative recurrence.
  • ERCP is used to retrieve hydatid material from the biliary tract, and surgical resection or percutaneous aspiration may be necessary for definitive treatment.

Table 45.5 Distribution, Clinical Complications, and Treatment of Other Biliary Parasites

Parasite	Distribution	Complications	Treatment
Opisthorchis and Clonorchis	Far East, Southeast Asia, and Eastern Europe	- Recurrent pyogenic liver cholangitis- Cholelithiasis- Cholangiocarcinoma	PZQ ± antibiotics
PZQ ± surgery
Surgery/chemotherapy/PZQ
Ascaris	Worldwide	- Biliary obstruction with cholangitis
- Pancreatitis
- Ileal volvulus, perforations, intussusceptions, and impacted multiple worm boluses	ERCP to remove adult parasite ± albendazole
Echinococcus granulosus	Worldwide	- Hepatic hydatid cyst rupture into biliary tree	Albendazole followed by ERCP ± sphincterotomy

Abbreviations:

• PZQ: Praziquantel
• ERCP: Endoscopic retrograde cholangiopancreatography

Summary Table of Key Parasitic Infections Affecting the Biliary Tract

Parasite	Geographic Distribution	Clinical Manifestations	Primary Treatment
Ascaris lumbricoides	Tropical regions	Biliary colic, jaundice, pancreatitis, cholangitis	Albendazole
Echinococcus granulosus	Global (sheep-raising areas)	Hydatid cyst rupture, cholangitis, biliary obstruction	Albendazole + ERCP
Fasciola hepatica	Global (sheep and cattle areas)	Acute phase: fever, hepatomegaly; Chronic phase: cholangitis, fibrosis	Triclabendazole
Clonorchis sinensis	Asia (China, Korea, Vietnam)	Cholangitis, cholangiocarcinoma, cholecystitis	Praziquantel
Opisthorchis viverrini	Southeast Asia (Thailand, Laos)	Cholangitis, cholangiocarcinoma, hepatomegaly	Praziquantel
Schistosoma mansoni	Africa, South America, Middle East	Portal hypertension, hepatosplenomegaly, fibrosis	Praziquantel
Dicrocoelium dendriticum	Europe, Asia, North America (rare)	Biliary colic, jaundice, hepatomegaly	Praziquantel or Albendazole

Question Title: Drug of Choice for Asiatic Cholangiohepatitis

Question:

A 23-year-old male patient is diagnosed with Asiatic cholangiohepatitis. What is the drug of choice for this condition?

Options: A) Mebendazole

B) Albendazole

C) Metronidazole

D) Secnidazole

Correct Answer:B) Albendazole

Explanation:

• Praziquantel and albendazole are the drugs of choice for Asiatic cholangiohepatitis. This condition is commonly associated with parasitic infections, particularly liver fluke infestations.
• While these medications are effective, surgical challenges can arise, especially when there are stones present not only in the gallbladder but also in the common bile duct, requiring careful management.

Reference: Bailey & Love's Short Practice of Surgery, 28th Edition, Page 71.