Podcast
Questions and Answers
What type of granuloma is surrounded by fibroblasts and capillaries?
What type of granuloma is surrounded by fibroblasts and capillaries?
What is the result of dead worms being trapped inside venules of the coarse tracts?
What is the result of dead worms being trapped inside venules of the coarse tracts?
What is the characteristic of the liver in Bilharzial affection?
What is the characteristic of the liver in Bilharzial affection?
What is the main location of ova deposition in Bilharzial affection?
What is the main location of ova deposition in Bilharzial affection?
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What is the function of Kupffer cells in Bilharzial affection?
What is the function of Kupffer cells in Bilharzial affection?
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What is the result of Bilharzial affection on the hepatic lobules?
What is the result of Bilharzial affection on the hepatic lobules?
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What is the characteristic of Angiomatoids in Bilharzial affection?
What is the characteristic of Angiomatoids in Bilharzial affection?
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What is the result of coarse bilharzial periportal fibrosis?
What is the result of coarse bilharzial periportal fibrosis?
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What is the characteristic of the immune response in chronic schistosomiasis?
What is the characteristic of the immune response in chronic schistosomiasis?
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What is the result of the inflammatory response caused by trapped ova?
What is the result of the inflammatory response caused by trapped ova?
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In which stage of schistosomiasis are TH1 cells dominant?
In which stage of schistosomiasis are TH1 cells dominant?
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What is the location of the adult worms in S. hematobium infection?
What is the location of the adult worms in S. hematobium infection?
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What is the characteristic of the lesions produced by cercaria?
What is the characteristic of the lesions produced by cercaria?
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What is the result of the recurrent bleeding caused by the spines of ova?
What is the result of the recurrent bleeding caused by the spines of ova?
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What is the composition of the cellular granuloma?
What is the composition of the cellular granuloma?
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What is the role of IL-4 in the immune response to Schistosoma infection?
What is the role of IL-4 in the immune response to Schistosoma infection?
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What is the primary cause of portal hypertension in hepatic bilharziasis?
What is the primary cause of portal hypertension in hepatic bilharziasis?
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What is the characteristic gross picture of the liver in hepatic bilharziasis?
What is the characteristic gross picture of the liver in hepatic bilharziasis?
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What is the effect of portal hypertension on the spleen?
What is the effect of portal hypertension on the spleen?
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What is the consequence of ammonia escaping into the systemic circulation?
What is the consequence of ammonia escaping into the systemic circulation?
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What is the characteristic microscopic feature of the hepatic lobules in hepatic bilharziasis?
What is the characteristic microscopic feature of the hepatic lobules in hepatic bilharziasis?
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What is the cause of ascites in hepatic bilharziasis?
What is the cause of ascites in hepatic bilharziasis?
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What is the common complication of portal hypertension in hepatic bilharziasis?
What is the common complication of portal hypertension in hepatic bilharziasis?
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What is the relatively common cause of death in hepatic bilharziasis?
What is the relatively common cause of death in hepatic bilharziasis?
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Study Notes
Bilharziasis
- Chronic specific granulomatous infection caused by Schistosoma species
- Endemic in Egypt
Life Cycle and Pathogenesis
- Acute schistosomiasis:
- Severe febrile illness, peaks after 2 months
- Dominated by TH1 cells, producing IFN-γ, stimulating macrophages to secrete cytokines (TNF, IL-1, and IL-6) → fever
- Chronic schistosomiasis:
- Associated with dominant TH2 response, although TH1 cells persist
- Parasite egg proteins stimulate mast cells to produce IL-4 → TH2 differentiation
- Both TH1 and TH2 cells contribute to granuloma formation around eggs
Bilharzial Lesions
- Produced by cercaria:
- Acute allergic dermatitis, maculopapular skin rash
- Microscopic picture: dilated capillaries, neutrophils, eosinophils, and macrophages
- Produced by adult worms:
- Live in veins around bladder (S. hematobium) or colon (S. mansoni)
- Dead worms → severe inflammation, necrosis, and thrombophlebitis
- Living worms → brown bilharzial pigment engulfed by phagocytic cells of liver, spleen, and other tissues
- Produced by ova:
- Recurrent bleeding (due to injury by ova spines) leads to anemia
- Ova may be trapped in bladder, intestine, or carried to lungs, liver, or other sites
- Trapped ova produce "egg antigens" leading to T-lymphocyte sensitization, lymphokine release, and inflammatory response → granuloma formation
Granuloma Development
- Three successive phases:
- Cellular granuloma: ova surrounded by macrophages, eosinophils, neutrophils, lymphocytes, and giant cells
- Fibro-cellular granuloma: cellular granuloma surrounded by fibroblasts and capillaries
- Fibrous (healed) granuloma: smaller, dense collagen, with inflammatory cells disappearing
Liver Bilharziasis
- Common in patients with intestinal bilharziasis
- Portal tracts show major changes:
- Ova carried as emboli through portal vein and trapped in small and large portal tracts
- Granulomas → fibrosis
- Dead worms → trapped inside venules of coarse tracts, leading to thrombophlebitis
- Angiomatoids: dilated capillaries in fibrotic portal tracts, representing dilated collateral channels between hepatic artery and portal veins
- Hepatic lobules show minimal insignificant lesions, with preserved architecture
Types of Bilharzial Periportal Fibrosis
- Fine bilharzial periportal fibrosis:
- Bilharzial affection predominantly involves fine tracts
- Lesions produced by ova
- Gross picture: normal-sized liver, firm, finely granular surface, and dark brown cut surface
- Microscopic picture: ova, granulomatous inflammation, and fibrosis in portal tracts
- Coarse bilharzial periportal fibrosis:
- Bilharzial affection predominantly involves coarse tracts
- Lesions produced by ova and/or dead worms
- Gross picture: reduced liver size, firm, irregular surface, and dark brown cut surface
- Microscopic picture: ova, granulomatous inflammation, and fibrosis in portal tracts
- Mixed fine and coarse bilharzial periportal fibrosis:
- The usual pattern
Effects and Complications
- Portal hypertension:
- Caused by portal fibrosis and angiomatoids
- Effects: splenomegaly, ascites, and opening of porto-systemic venous collaterals
- Portal vein thrombosis: may occur due to vascular stasis
- Mild disturbances of liver functions: lowering of plasma proteins
- Ascites: due to portal hypertension and lowering of plasma proteins
- Ammonia encephalopathy:
- Normally, ammonia is converted to urea in the liver
- Hepatic portal fibrosis → ammonia escape through open porto-systemic collaterals → reach systemic circulation → brain → encephalopathy → coma
- Causes of death in hepatic bilharziasis:
- Bleeding (hematemesis)
- Superimposed chronic viral hepatitis (relatively common) leading to cirrhosis and liver failure
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Description
This quiz covers the causes and pathogenesis of bilharziasis, a chronic granulomatous infection caused by Schistosoma species. Learn about the life cycle and acute and chronic stages of the infection.
