VPA 211: General Veterinary Parasitology and Helminthology (3+1)

PATHOGENESIS

• Two clinical syndromes are seen in animals infected with schistosomes, an acute intestinal syndrome and a chronic hepatic syndrome
• After heavy infection there is inflammatory and granulomatous responses to the deposition of eggs in the mesenteric veins and their subsequent infiltration in the intestinal mucosa
• During the acute phase of the disease there are marked haemorrhagic lesions in the mucosa of the intestine, but as the disease progresses the wall of the intestine appearse greyish, thickned and edematous due to confluence off the egg granulomata and the associated inflammatory changes.
• The hepatic syndrome is an immunological disease resulting from the host's cell mediated immune response to schistome eggs in the liver
• Eggs swept back in the portal circulation lodge in perisinusoidal interlobular portal venules. Immunologically specific host reaction to the eggs leads to extensive damage to the portal vascular system.