Summary about Disease
Liver fluke infection (also known as fascioliasis) is a parasitic infection caused by the liver flukes Fasciola hepatica and *Fasciola gigantica*. These parasites infect the liver and bile ducts of humans and various grazing animals. Humans typically acquire the infection by consuming raw or undercooked freshwater plants, such as watercress, that are contaminated with fluke larvae. While treatable, chronic infections can lead to serious liver and biliary complications.
Symptoms
Symptoms of liver fluke infection can vary depending on the stage of infection.
Acute Phase: Abdominal pain (especially in the upper right quadrant), fever, nausea, vomiting, diarrhea, loss of appetite, urticaria (hives), and fatigue. Eosinophilia (elevated levels of eosinophils, a type of white blood cell) is common.
Chronic Phase: Intermittent abdominal pain, jaundice (yellowing of the skin and eyes), inflammation of the bile ducts (cholangitis), gallstones, and liver enlargement. In severe cases, liver fibrosis or cirrhosis can develop.
Causes
Liver fluke infection is caused by ingesting metacercariae (infective larvae) of Fasciola hepatica or *Fasciola gigantica*. The life cycle of the fluke involves: 1. Eggs are passed in the feces of infected animals or humans. 2. In water, the eggs hatch into miracidia, which infect freshwater snails. 3. Within the snail, the miracidia develop into cercariae. 4. Cercariae are released from the snail and encyst on aquatic vegetation as metacercariae. 5. Humans or animals become infected by eating raw or undercooked aquatic plants (especially watercress) containing metacercariae. 6. The metacercariae excyst in the small intestine, penetrate the intestinal wall, and migrate to the liver, where they mature into adult flukes in the bile ducts.
Medicine Used
The primary medication used to treat liver fluke infection is triclabendazole. It is highly effective against both Fasciola hepatica and *Fasciola gigantica*. The dosage and duration of treatment are determined by a healthcare professional. An alternative medication, although less effective, is bithionol.
Is Communicable
Liver fluke infection is not directly communicable from person to person. Transmission occurs through the ingestion of contaminated aquatic vegetation. It's a zoonotic disease, meaning it primarily cycles between animals and snails, with humans becoming accidental hosts.
Precautions
To prevent liver fluke infection:
Avoid eating raw or undercooked freshwater plants, especially watercress. Thoroughly wash and cook aquatic vegetables before consumption.
Practice good hygiene. Wash hands thoroughly with soap and water after handling aquatic plants or working in areas where livestock graze.
Control snail populations in areas where livestock graze.
Improve sanitation and prevent contamination of water sources with human or animal waste.
Educate people in endemic areas about the risks of eating raw aquatic plants.
How long does an outbreak last?
The duration of an outbreak depends on the source of contamination and the effectiveness of control measures. Localized outbreaks linked to a specific contaminated watercress patch might resolve quickly once the source is identified and consumption ceases. However, in endemic areas with widespread contamination and poor sanitation, sporadic cases may continue to occur over extended periods. A single infection, if untreated, can last for many years, even decades.
How is it diagnosed?
Diagnosis of liver fluke infection typically involves:
Stool Examination: Microscopic identification of fluke eggs in stool samples. Multiple samples may be needed as egg shedding can be intermittent.
Serological Tests: Blood tests that detect antibodies against Fasciola antigens. These tests can be more sensitive than stool examination, especially in the early stages of infection before egg production begins.
Imaging Studies: Ultrasound, CT scan, or MRI of the liver to detect bile duct abnormalities or liver damage.
Duodenal Aspirate or Bile Examination: In some cases, eggs or adult flukes can be identified in samples taken directly from the duodenum or bile ducts.
Timeline of Symptoms
The timeline of symptoms can vary.
Incubation Period: The time between ingestion of metacercariae and the onset of symptoms is typically weeks to months.
Acute Phase: Symptoms typically begin 2-4 weeks after infection and can last for several months.
Chronic Phase: Symptoms may appear months to years after the initial infection and can persist for many years if left untreated. It is characterized by more insidious and chronic symptoms.
Important Considerations
Liver fluke infection is a neglected tropical disease that disproportionately affects impoverished communities in areas with poor sanitation and agricultural practices.
Diagnosis can be challenging, especially in the early stages of infection or when egg shedding is intermittent.
Prompt diagnosis and treatment with triclabendazole are crucial to prevent chronic complications.
Public health efforts should focus on preventing infection through education, improved sanitation, and control of snail populations.
Co-infections with other parasites are common in endemic areas and should be considered during diagnosis and treatment.