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What to Know About Liver Fluke (Fasciola)

Medically Reviewed by Melinda Ratini, DO, MS on June 29, 2021

Liver flukes (fasciola) are parasitic flatworms that affect the bile duct and liver. These flatworms may cause liver fluke disease (fascioliasis). Liver flukes mainly affect livestock (sheep, goats, and cows) and people. However, they affect animals more than they do humans.‌

There are two types of liver flukes that affect humans. They are Fasciola hepatica (common liver fluke or sheep liver fluke) and Fasciola gigantica.

Symptoms of Liver Fluke

People can get infected with liver flukes after swallowing the parasite, most often by eating raw vegetables or drinking contaminated water. 

In some cases, an infected individual may never feel sick or show signs of infection. The symptoms you get may vary depending on the stage of infection you're in. You may experience some symptoms during the early stages as the liver flukes move in the intestines, liver, and the abdominal cavity.‌

You may also experience symptoms in the late stages of infection. This is when the liver fluke has reached the bile duct (the liver's duct system). The symptoms associated with this stage may appear months or even years after you get infected. Two common symptoms of this phase are blockage of the ducts and inflammation.‌

You may also show symptoms like:

Life Cycle of the Liver Fluke

Infected animals excrete immature eggs through their stool. These eggs develop in freshwater, using snails as an immediate host to undergo several developmental stages. The snail later releases the eggs onto plants, which are ingested by grazing animals and passed on to humans, where they live to adulthood. Humans may also consume the parasite directly through the plants.

Stages of Liver Fluke Infections

Liver fluke infection is categorized into three stages:

  1. Acute stage. This phase describes the time from the fourth to the seventh day after contact with the parasite. You may not detect the signs or symptoms, and it may go on for two or up to four months.
  2. Latent stage. During the latent phase, the liver flukes are already mature, and they head to the bile duct. This stage may go on for a few months.
  3. Chronic stage. In this stage, mature worms may cause adverse effects as they excrete their metabolic waste in the liver and bile. This may lead to blocking of the bile duct and inflammation.

Diagnosis of Liver Fluke Infection

Diagnosis of liver fluke infection is made through some of these tests:

  • Blood tests. Doctors can identify liver fluke antibodies (proteins produced by the body to help fight any infection). In other cases, doctors may also check your white blood cell count. White blood cells increase as your body tries to fight off infections.
  • Liver imaging. The medical practitioner uses liver imaging to check if the liver flukes have caused any damage to the bile duct or liver. Imaging involves endoscopic retrograde cholangiopancreatography (ERCP), cholangiography, computed tomography (CT), ultrasonography, and magnetic resonance imaging (MRI) tests. In some cases, doctors may opt to perform an endoscopy (inserting a long thin tube with a camera at the tip) into the mouth to the stomach to diagnose liver fluke infection. 
  • Stool tests. A stool test is used to trace any liver fluke eggs in the stool.

Treatment of Liver Fluke

Liver fluke infection is treatable. You should consult a professional if you suspect you have a liver fluke infection to prevent complications.

Medication. Anthelmintic drugs get administered to get rid of liver flukes. Depending on whether its Fasciola hepatica or Fasciola gigantica, your doctor may prescribe the following anthelmintic medications:

Surgery. Surgery may be an option to help unblock the bile duct. 

Prevention

Liver fluke infections are easily preventable. Prevention methods may include:

  • Ensuring that wild edible aquatic plants such as watercress are well-cooked before eating
  • Avoiding food and water from suspected contaminated areas 
  • Ensuring fish from freshwater areas are well-cooked before eating
  • Ensuring proper hygiene before handling food or water‌

People living near areas where livestock graze should also take necessary caution before ingesting food or water. The presence of livestock increases the chances of infection. Regular inspection of animals is encouraged to contain infections. ‌

Generally, liver fluke infections are not fatal. Those who become infected often survive without any complications because infections are treatable.

WebMD Medical Reference

Sources

SOURCES:

Centers for Disease Control and Prevention: "Fasciola FAQs," "Biology."

‌Merck Manual: "Fluke Infections of the Liver."

National Organization for Rare Disorders: "Fascioliasis."

Reed College: "Parasitic Behaviors of the Lancet Liver Fluke."

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