Food-borne trematodes

Published on October 29, 2020   36 min

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Hello, I'm Professor Russell Stothard from the Liverpool School of Tropical Medicine. This lecture is going to concentrate on food-borne trematodes. These are all medical helminths and cause disease throughout the world. This is an introduction lecture to some of those foodborne trematodes, but not all. I can be contacted at the e-mail address below.
Parasitic worms of medical importance can be divided into two groups. On the right-hand side, in the blue, we have the nematodes or the roundworms, but we are not going to talk about those today. We are looking at the flatworms or the platyhelminthes. Two major groups within the platyhelminthes; the cestodes, which is the tapeworms, in yellow, and the trematodes, the flukes. Also, in the right-hand side, the trematodes gets split into two different subdivisions. We can think of the blood flukes, which is the schistosomes, but also think of the tissue flukes. These are leaf-like objects, the flatworms, and they live inside the body cavities of either the lungs, the gut, or bowel. We have various species assigned to these tissue flukes. We have fasciola hepatica and gigantica. This is commonly known as the European liver fluke, although it can be found in many parts throughout the world. We have two other Chinese or Asian liver flukes called opisthorchis viverrini and felineus, as well as clonorchis sinensis, which you find in China. Then, there's going to be another fluke which we're only going to lightly touch upon, which is the lung fluke, paragonimus westermani.
These parasites are found in the body cavities, mainly, the liver, such as biliary tree, the bowel, bowel lumen, as well as the lungs. We're going to look at the natural history of the parasites. The image on the right shows some fasciola hepatica worms. You can see that they look like small, flattened leaf. They're hermaphrodites. They're quite large, so consider these animals inside your liver cause mischief. The image below is actually the ultrasound scan of the gall bladder. You can see a circular dark objects inside it, which looks like a small string. Those are fasciola worms inside the gall bladder causing mischief. We'll look at the natural history of the parasites, how they play out in their environment. You can consider them as actors on the stage, how they're adapted to the lifecycle for an infection, but also, we'll look at the clinical presentations of the disease that mainly cause acute and chronic symptoms, and they can be life-threatening in certain instances.