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| − | ====[[Liver Cestodes]]==== | + | ====[[Liver Trematodes]]==== |
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| − | ====Trematodes====
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| − | *flukes are important pathogens of the [[Liver - Anatomy & Physiology|liver]]
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| − | *Fascioliasis is among the most important parasitic conditions of sheep and cattle and is common
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| − | =====Fasciola hepatica=====
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| − | *common [[Liver - Anatomy & Physiology|liver]] fluke
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| − | *intermediate host
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| − | **aquatic snails
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| − | **therefore infestation is more common in damp or poorly drained pastures
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| − | *final host
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| − | **cattle and sheep
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| − | *can cause severe haemorrhagic [[Liver - Anatomy & Physiology|liver]] damage
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| − | *death in heavy infestations in sheep during migratory phase (1 month) through the [[Liver - Anatomy & Physiology|liver]] tissue
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| − | *recovered animals will have scarred [[Liver - Anatomy & Physiology|livers]]
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| − | *more commonly associated with chronic bile duct inflammation - cholangitis [need link to below]
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| − | **the adults live in the bile ducts
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| − | '''Acute Fascioliasis'''
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| − | *acute disease associated with immature fluke migration through the [[Liver - Anatomy & Physiology|liver]]
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| − | *occurs in late autumn and winter
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| − | *severity of outbreaks depend on a number of epidemiological factors
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| − | *the [[Liver - Anatomy & Physiology|liver]] of animals which die of this disease will be
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| − | **enlarged
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| − | **haemorrhagic
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| − | **honeycombed with the tracts of migrating flukes
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| − | ***tracts become filled with blood and degenerate hepatocytes later infiltrated with [[Eosinophils - WikiBlood|eosinophils]], [[Lymphocytes - WikiBlood|lymphocytes]] and replaced by fibrosis
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| − | **surface is covered with a fibrinous peritonitis, especially the ventral lobe
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| − | **subcapsular haemorrhages are frequent
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| − | **rupture into the abdomen is not an uncommon finding
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| − | '''Chronic Fascioliasis'''
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| − | ======Gross======
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| − | *[[Liver - Anatomy & Physiology|liver]] is reduced in size, unevenly
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| − | **left lobe is most severely affected with atrophy of the extremities
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| − | *hypertrophy may occur in some cases
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| − | **dorsal lobe
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| − | **this changes size and distorts shape of [[Liver - Anatomy & Physiology|liver]]
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| − | *the surface will be uneven with areas of fibrous tissue replacing the cells damaged by the migrating flukes
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| − | *bile ducts
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| − | **prominent thick protruding white bile ducts on the '''visceral surface''' spreading from the hilus to the left lobe
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| − | **the bile ducts are dilated, black, and calcified on '''cut surface'''
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| − | **numerous adult flukes can be expressed from the bile ducts
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| − | **chronic cholangitis
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| − | **''''pipe stem'''' appearance in cattle because bile ducts are very much thickened and often calcified
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| − | *bile
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| − | **dark brown, thick, and gritty in consistency
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| − | NB: the fibrosis which occurs in the chronic stage is realted only partly to the healing of the migratory tracts and the rest may be related to the development of immunity and rechallenge
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| − | ======Microscopically======
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| − | *reactive hyperplasia of the bile ducts
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| − | *substantial inflammatory cell infiltrate and peripheral fibrosis
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| − | *calcification of the chronically damaged tissue
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| | ===Protozoal=== | | ===Protozoal=== |