This episode examines trematodes, or flukes - leaf-shaped flatworms characterised by complex life cycles involving freshwater snails. Drawing from Murray’s Chapter 75, it explores transmission dynamics, tissue localisation, and chronic disease.
Trematodes are hermaphroditic (with the exception of Schistosoma species) and require intermediate hosts. Human infection typically occurs via:
Skin penetration by cercariae (Schistosoma)
Ingestion of contaminated water plants or undercooked fish
Major disease categories include:
Schistosomiasis - blood flukes causing granulomatous inflammation around eggs in liver or bladder
Liver flukes (e.g., Clonorchis, Fasciola) - biliary obstruction and chronic inflammation
Intestinal flukes - gastrointestinal irritation
Pathology is often driven by immune response to deposited eggs rather than adult worms.
Conceptually, trematodes illustrate multi-host ecological dependence. Clinically, freshwater exposure and dietary habits are essential diagnostic clues.
Key Takeaways
Trematodes are leaf-shaped flatworms
Freshwater snails are key intermediate hosts
Schistosoma penetrates intact skin
Disease often results from egg-induced granulomas
Chronic infection may cause organ fibrosis
