Life Cycle of Fasciola hepatica and Pathogenesis of Fascioliasis

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(Edited)

Hello everyone, today I will be writing on fascioliasis, an infection which is caused by fasciola hepatica also known as common liver fluke or sheep liver fluke so its distribution is same as what is expected from sheep raising since sheeps can serve as reservoir host, and the dominant animal affected. Fascioliasis has its history as far as Francesco Redi, Carl Linneaus who named the parasite, and Friedrick Leuckart who desceibed the life cycle of Faciola hepatica.


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The life cycle involves a host, an intermediate host, and a warm blooded mammalial host. The metacercariae forms beneath the scale of a fish and it feeds on vegetables which grow on the water bed, and stay in the body of the plants where sheeps comes to consume. Just as the sheep gets infected, so does the farmer if they also eat the vegetations without properly cooking them or when they eat them raw such as plants like watercress. If the metacercariae is injested, the accellular outside layer of the fasciola hepatica which protects it from the harsh environment is removed and digested, and fasciola hepatica goes to penetrate the small intestine where it get migrates into the liver tissue where it begins to feed on the liver tissue and grow.

We know that the liver regenerates, but then Fasciola hepatica secretes prolene to cause the liver to regenerate very fast but it can also cause the hyperplasia of the tissues. It keeps producing eggs since it is an hermaphrodite, it can fertilize its eggs by itself. The egg are sent to the small intestine where they are sent to the large intestine then are passed out through fecal waste. The egg can hatch in water where they can penetrate the foot of snails where they undergo multiplication events in the snail's tissue after which they become Cercaria which leaves the snail to watercrests after which they are eaten by sheep where the same life cycle process in humans continue. To explain the stages of Fasciola Hepatica, it goes from the Egg which contains underdeveloped Miracidium then into Snails where they develop into Cercaria which then leaves the snail and stay on water plants. When on water plants, they develop metacercaria which is the state they would be protected with an outer shell to prevent from environmental harshness, When swallowed, it would develop into the adult Fasciola hepatica.


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Clinical Pathogenesis of Fasciola hepatica will include stomach pain, but individuals may develop the symptoms after about one month of the immature worm being injested. Although many people who are infected are assymptomatic during the early phase and patients who are symptomatic will experience fever, headache, pain in the righ upper quadrant of the abdomen, generalized malaise, myalgia, weight loss, and urticaria. When the disesase is chronic, patients experience dull pain, and the gall bladder can get damaged. Findings with CT scan have reported hypoattenuating tracts after the path of helmith invasion from the liver capsule. The liver can also become tender and enlarged.

Diagnosing Faciola Hepatica would include performing serelogy test which would be positive even in the early stage. Antigen test would be done for specificity and sensitivity. Microscopy can be done but this is usually performed in the later phase when the worm is alread laying eggs, and the eggs are found in feces. Endoscopy can be done to help see the fluke. Other imaging such as CT, MRI, Ultrasound, and Cholangiography can be done. This is treated using Triclabendazole where it is given once but in severe cases, it can be repeated after 24 hours. This disease doesn't have to do with standard of living, it has to do with eating habit. The disease is still predominant in places where sheeps are eaten even though the standard of living is high there.

Reference

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The detailed explanation of the life cycle of Fasciola hepatica, from its intermediate hosts to its impact on humans, is truly informative. It's interesting to learn about the various stages of the parasite and how it affects different organs in the body. The clinical manifestations and diagnostic methods you mentioned provide valuable insights into the disease. It's worth noting that fascioliasis can occur regardless of the standard of living, emphasizing the importance of proper cooking and eating habits.

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Thanks a lot for the comment. This is common in people who eat sheep and not even based on the standard of living. It is amazing how big Fasciola hepatica is when it gets into the body.

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Hi! Is your enter key broken?

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Oh!!! I get it, I was trying to explain the life cycle and didn't want to break the explanation.... Let me get a new enter key and use it :)

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