Liver flukes are parasites that can cause disease in humans and some animals.
Liver flukes cannot be spread from person to person. Instead, people and animals get infected with liver flukes by eating contaminated fish or drinking contaminated water.
Image credit: Veronidae, 2013
Liver flukes are parasitic worms that live in the bile ducts and the liver of infected animals. These parasites cause a disease called fascioliasis in people, cattle, and sheep.
Although liver flukes can infect people in all parts of the world, they are most prevalent in developing countries.
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It is not possible to spread liver flukes from person to person, and some infected people may not even realize they have them. Once contracted, liver flukes may live in a person’s body for 20 to 30 years if left untreated.
How do people get infected?
People most commonly get infected with liver flukes through the following ways:
- consuming freshwater fish infested with the flukes
- eating freshwater vegetables, such as watercress
- drinking contaminated water
- washing vegetables or fruits with contaminated water
The scientific name for liver flukes is Fasciola, and the disease they cause is called fascioliasis. The Centers for Disease Control and Prevention (CDC) have identified two types of liver flukes that can infect people: Fasciola hepatica and Fasciola gigantica.
A person may have liver flukes living in them and never develop fascioliasis. Others may develop fascioliasis many years after the liver flukes entered their body.
A person may never know they have liver flukes. Some doctors may not diagnose the condition because the symptoms of fascioliasis are similar to many other conditions.
Unlike some other parasites and diseases, a person cannot pass liver flukes accidentally to someone else.
Individuals who do develop symptoms may experience some or all of the following:
Abdominal pain
Once in a person’s body, liver flukes make their way from the intestines to the liver. For them to get into the liver, the liver flukes must burrow through the lining of the liver, which causes pain in the upper right abdomen.
Years after being infected, a person may experience periods where the bile ducts get blocked, which also causes abdominal pain.
Nausea, diarrhea, and vomiting
A person may experience vomiting, diarrhea, and nausea during the early stages of infection or while the bile ducts are blocked.
These symptoms can last several weeks to several months, depending on the severity of the infection.
Weight loss
In addition to nausea, a person may have a lack of appetite. A loss of appetite can cause weight loss if it persists over time.
Hives
The immune system often reacts to the liver flukes, causing hives to appear on the body. This symptom is most common during the early stages of the infection as the liver flukes burrow into the liver.
Fever
Fever is most common during the earlier stages of the infection and when the bile ducts are blocked.
Malaise
Malaise is a term used to describe a general or overall sense of not feeling well. As with some of the other symptoms, malaise is most common during the early stages and during times when the bile ducts are blocked. Between episodes, this feeling of malaise typically goes away.
It may be difficult to determine if a person has liver flukes. Infections are more common in people in developing countries that live near cattle. In these areas, a doctor may be better able to diagnose the disease.
In developed countries such as the U.S., it may be harder to get a diagnosis because liver flukes are far less common.
It is a good idea for a person who has traveled to an at-risk region outside of the U.S. to tell a doctor if they experience any symptoms that may be caused by liver flukes. A doctor will likely need to rule out other more serious infections that have similar symptoms.
To be diagnosed, a person needs to have mature liver flukes whose eggs have passed into the stool. A doctor will take a stool sample to run tests that find the eggs.
A medication called triclabendazole is commonly used to treat a liver fluke infection, as this effectively kills the liver flukes and their eggs.
Other drugs, such as pain relievers, may be used to treat some of the symptoms such as pain and diarrhea.
Surgery may be necessary in rare cases where cholangitis, an infection of the bile ducts in the liver, has developed.
A person can help prevent a liver fluke infection by:
- cooking all vegetables grown near cattle and sheep
- cooking animal livers and not consuming them raw
- boiling all untreated water
- not drinking water directly from a stream near where cattle and sheep live
Conclusion
Though liver flukes may sound alarming, they are not a common threat in most developed parts of the world. Simple precautions, such as not drinking untreated water and cooking vegetables grown near at-risk areas, can keep a person infection-free.
If a person develops symptoms of a liver fluke infection, it is important for them to visit a doctor for proper diagnosis and treatment.