Parasitic Diseases Lectures #43: Fascioliasis

Summary

This video explores Fascioliasis, an infection caused by the liver fluke Fasciola hepatica, primarily affecting sheep, which serve as a reservoir host. The lifecycle involves a snail intermediate host and is linked to watercress consumption. Symptoms in humans include liver pain, fever, weight loss, and eosinophilia, with diagnosis relying on serology and imaging. Treatment involves the use of triclabendazole, not praziquantel, and prevention focuses on education and hygiene, though control remains challenging due to cultural habits. The video provides insights into clinical presentation, diagnosis, and management of this parasitic disease.

Takeaways

• 😀 Fasiola hepatica, also known as the sheep liver fluke, is distributed worldwide, primarily in regions where sheep are raised, and they serve as a reservoir host for the infection.
• 😀 The lifecycle of Fasiola hepatica involves a snail intermediate host and a warm-blooded mammalian host, with sheep and humans being common hosts.
• 😀 Infection is commonly caused by ingesting watercress contaminated with the larval stage of the parasite, which can be found growing in areas where sheep gather.
• 😀 Once ingested, the parasite migrates through the intestines and liver, feeding on liver tissue and stimulating the growth of additional tissue, leading to damage.
• 😀 Fasiola hepatica is a hermaphroditic parasite, meaning it self-fertilizes before laying eggs that pass through the liver into the biliary system and are excreted in feces.
• 😀 Eggs hatch into miracidia, which then infect snails, leading to the release of cercariae that eventually attach to vegetation in freshwater environments.
• 😀 Clinical symptoms of infection include right upper quadrant pain, liver enlargement, and eosinophilia, though many infected individuals may remain asymptomatic.
• 😀 Diagnosis can be challenging in early stages as eggs are not yet present in the stool, but serology and antigen tests can be used to detect the infection.
• 😀 Imaging techniques such as CT scans and ultrasound can reveal liver damage caused by the parasite, including migratory tracks and adult flukes in liver tissue.
• 😀 Treatment for Fasiola hepatica infection includes the use of triclabendazole, which is effective in clearing the parasite, but treatment access may require coordination with the CDC in the U.S.

Q & A

What is Fasciola hepatica commonly known as?

Fasciola hepatica is commonly known as the sheep liver fluke.

What is the primary reservoir host for Fasciola hepatica?

The primary reservoir host for Fasciola hepatica is the sheep, although humans can also become infected.

How does Fasciola hepatica spread in the environment?

Fasciola hepatica spreads through eggs that are excreted in the feces of infected animals. These eggs hatch in freshwater, releasing larvae that infect snails. The larvae then transform into cercaria, which attach to aquatic plants and can be ingested by hosts.

What role does watercress play in the transmission of Fasciola hepatica?

Watercress, an aquatic plant, plays a role in the transmission of Fasciola hepatica because it can become contaminated with cercaria larvae. If consumed raw, it can lead to infection.

What symptoms may indicate an infection with Fasciola hepatica?

Symptoms of a Fasciola hepatica infection include fever, right upper quadrant pain, headache, malaise, muscle pain, weight loss, and in severe cases, liver enlargement and pleural effusion.

What imaging techniques are useful in diagnosing Fasciola hepatica infection?

Imaging techniques such as CT scans, ultrasounds, and MRIs can be used to visualize migratory tracks in the liver and the presence of adult flukes.

What is the first-line treatment for Fasciola hepatica infections?

The first-line treatment for Fasciola hepatica infections is Triclabendazole, which selectively targets the fluke's structure, preventing its growth and reproduction.

Why is Praziquantel not effective against Fasciola hepatica?

Praziquantel is not effective against Fasciola hepatica because it does not target the specific mechanisms required to treat this parasite. Triclabendazole is the recommended treatment instead.

How can Fasciola hepatica infection be prevented in sheep-raising regions?

Prevention involves improving sanitation to properly dispose of feces, educating sheep farmers about the risks of consuming contaminated plants like watercress, and encouraging the separation of grazing areas from water sources.

What is the importance of serological tests in diagnosing Fasciola hepatica infection?

Serological tests are important for diagnosing Fasciola hepatica early in the infection process, as they detect the immune response before eggs appear in the stool, allowing for timely intervention.