Parasitic disease caused by several species of flatworm Affects
many in developing countries a disease caused by parasitic worms.
The organisms (a type of fluke) inhabit tropical lakes and rivers,
completing part of their life cycle in snails. They leave the
snails as cercariae, which can infect humans by burrowing through
the skin as they bathe. The flukes attach themselves in the veins
of the intestine and bladder, and release eggs into these organs.
The eggs are then expelled with urine and faeces, and pass back
into the water. Chronic infections can damage many organs,
including the lungs (as here), brain and liver. Drugs can treat the
disease.
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Distribution Map
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Slide 6
In liver, m & f pair up female inserts herself into the
gynecophoral canal of male they are now paired. Migrate to favoured
sites: S. mansoni mesenteric venules of large bowel & rectum S.
japonicum mesenteric veins of the small intestine S. haematobium
perivesical venous plexus surrounding the bladder Paired male &
female
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Cercaria: Cause acute dermatitis Adult worms: o Living worms:
ingest blood and excrete brown bilharzial pigment o Dead worms:
cause severe allergic inflammation with necrosis and eosinophilic
infiltrate
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Ova: Produce granulomatous reaction formed of: Macrophages
Lymphocytes Plasma cells Eosinophils Few giant cells Fresh or
calcified bilharzial ova
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Ova: Produce granulomatous reaction formed of: Macrophages
Lymphocytes Plasma cells Eosinophils Few giant cells Fresh or
calcified bilharzial ova
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Bilharzial large intestine
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Section in large intestine. Bilharzial ova deposited mainly in
the submucosa and to a lesser extent in the mucosa and muscle
layers. Fresh ova show granular meracidium and surrounded by
refractile shell. Degenerated ova are pink, while calcified ova are
blue. The ova are surrounded by macrophages, plasma cells,
eosinophils, lymphocytes and foreign body giant cells. Old lesion
shows fibrosis. Diagnosis: Bilharziasis large intestine
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section in the secum shows multiple polyps ranging in size from
1x1 up to 2x2 some of them have stalk multiple bilharzial
polyps
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Bilharzial polyp
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Bilharzial bladder
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Section in a polyp shows: Central core of connective tissue
showing fresh, degenerated and calcified ova surrounded by
bilharzial reaction (described). The covering mucosa shows
hyperplastic glands surrounded by inflammatory infiltrate and
bilharzial ova. Diagnosis: Bilharzial polyp, colon.
Slide 16
Section in a bladder wall showing bilharzial ova deposited in
the submucosa and surrounded by bilharzial reaction (described).
Old lesions show fibrosis. The mucosa shows areas of hyperplasia,
atrophy, ulceration or squamous metaplasia.The hyperplastic
epithelium dips down in the submucosa to form Bruns nests. The
centers of the nest show degeneration to form cystitis cystica.
Dignosis: Bilharziasis, urinary bladder.
Slide 17
Bilharzia. Gross specimen of a lung showing damage (grey,
right) caused by bilharzia (schistosomiasis),