PARA3002 Lecture Notes - Lecture 3: Schistosoma Haematobium, Schistosoma Japonicum, Itch
Document Summary
Trematodes: metacercaria formation (environment & 2nd intermediate host) Eggs in rat faeces eggs eaten by terrestrial snail asexual reproduction in snail cercaria emerges from snail in slime trail . Cercaria enters 2nd intermediate host snail via excretory pore metacercaria formed in snail kidney. Asexual reproduction occurs in snail, producing cercaria cercaria emerges. & swims to plants cercaria encyst in environment sheep eats plants with metacercaria metacercaria in gi tract encysts in response to digestive juices. Penetrate gut & wanders in body cavity penetrate liver & wander. Enter main bile ducts undergoes sexual reproduction egg produced. Acute disease (mass migration of juveniles): tissue dmg, tissue necrosis, anaemia, black disease in sheep. Chronic disease: fibrotic hardened liver, biliary epithelial hyperplasia. Human disease: eat raw vegetables with metacercaria cause juveniles to wander in subcutaneous lumps e. g. eye monocular blindness rarely become adults in humans. Egg in faeces reach water egg eaten by snail undergoes asexual reproduction cercaria emerge from snail cercaria enters fish.