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693 bytes removed ,  18:03, 5 August 2010
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===Pathology===
 
===Pathology===
In acute fasciolosis, immature flukes grow and migrate within the liver parenchyma, causing necrotic tracts and haemorrhage. Damage to hepatocytes releases GDH, accounting for the elevation detectable in serum levels. The liver is also subject to post-necrotic scarring, where necrotic areas shrink and fibrose and normal tissues hypertrophy.
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[[Image:Fasciola  hepatica - bile duct.jpg|150px|thumb|right|Bile duct fibrosis due to chronic ''Fasciola hepatica'' infestation. Source: Wikimedia Commons; author: Flukeman]]
This occurs in late autumn  and winter, mainly  between the months of August to October. Outbreaks  of acute  fascioliasis usually present as sudden deaths.  On examination  infected  animals are weak, with pale mucous membranes.  They may also  have  enlarged livers, and the liver surface may be cover with a  fibrinous  peritonitis, particularly evident on the ventral lobe. Tracts  become  filled with blood and degenerate hepatocytes later infiltrated  with  [[Eosinophils|eosinophils]], [[Lymphocytes|lymphocytes]] and  replaced  by fibrosis.
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[[Image:Fasciola  hepatica - bile duct.jpg|300px|thumb|right|'''Fasciola hepatica  (Copyright Flukeman, Wikimedia Commons) ''']]
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====Subactute Fascioliasis====
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In acute fasciolosis, immature flukes grow and migrate within the liver parenchyma, causing necrotic tracts and haemorrhage. On post-mortem, the liver is enlarged and a fibrinous peritonitis may be be present. Fibrin takes are often particularly apparent on the ventral lobe. Histologically, tracts are seen as areas of degenerate hepatocytes and haemorrhage, which may later become infiltrated with eosinophils and lymphocytes. In the long term, these areas will become fibrosed.
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Subactute Fascioliasis
 
This  is caused by  ingestion of metacercariae over a longer period of time.  Some may have  migrated to the bile ducts, causing [[cholangitis]],  whilst other  metacercariae are migrating through the liver causing  lesions similar to  those present in acute fascioliasis.  The infected  host may present  with severe haemorrhagic anaemia, with  [[hypoalbuminaemia]], rapid loss  of body condition, reduced appetite,  pale mucous membranes, and  submandibular oedema may also be present. On  post-mortem, an enlarged  liver is common and haemorrhagic tracts are  usually visible on the liver  surface. If left untreated, it is often  fatal.  This form of  fascioliasis occurs around 6-10 weeks after  ingestion of the  metacercariae by the host, and like acute fascioliasis  occurs in late  autumn and winter.
 
This  is caused by  ingestion of metacercariae over a longer period of time.  Some may have  migrated to the bile ducts, causing [[cholangitis]],  whilst other  metacercariae are migrating through the liver causing  lesions similar to  those present in acute fascioliasis.  The infected  host may present  with severe haemorrhagic anaemia, with  [[hypoalbuminaemia]], rapid loss  of body condition, reduced appetite,  pale mucous membranes, and  submandibular oedema may also be present. On  post-mortem, an enlarged  liver is common and haemorrhagic tracts are  usually visible on the liver  surface. If left untreated, it is often  fatal.  This form of  fascioliasis occurs around 6-10 weeks after  ingestion of the  metacercariae by the host, and like acute fascioliasis  occurs in late  autumn and winter.
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====Chronic  Fascioliasis====
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Chronic  Fascioliasis
    
*'''Bile duct damage'''  
 
*'''Bile duct damage'''  
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Infected  animals may present with progressive loss of body  condtion, reduced  appeptite, which along with hypoalbuminaemia can  result in an gaunt  animal. Other common signs include pale mucous  membranes, and  submandibular oedema, more commonly known as 'bottle  jaw.'  On biopsy  the liver will have an irregular shape, distorted shape  with areas of  fibrous tissue replacing the cells damaged by the  migrating flukes. The  bile ducts appear dilated, and dark, and it is  often possible to  express numerous numbers of adult flukes from within  the ducts.  Pathology is similar in both sheep and cattle, expect in  cattle you may  see calcification of the bile ducts, and enlargement of  the gall  bladder. The calcified bile ducts are often seen protruding  from the  liver surface, which is known as 'pipe stem liver.'
 
Infected  animals may present with progressive loss of body  condtion, reduced  appeptite, which along with hypoalbuminaemia can  result in an gaunt  animal. Other common signs include pale mucous  membranes, and  submandibular oedema, more commonly known as 'bottle  jaw.'  On biopsy  the liver will have an irregular shape, distorted shape  with areas of  fibrous tissue replacing the cells damaged by the  migrating flukes. The  bile ducts appear dilated, and dark, and it is  often possible to  express numerous numbers of adult flukes from within  the ducts.  Pathology is similar in both sheep and cattle, expect in  cattle you may  see calcification of the bile ducts, and enlargement of  the gall  bladder. The calcified bile ducts are often seen protruding  from the  liver surface, which is known as 'pipe stem liver.'
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Metacercariae  excyst → immature  flukes present in the  small intestine → migrate  across the peritoneal  cavity (about 1 week) →  to the liver → migrate  through the liver  parenchyma for 6-7 weeks  becoming more destructive as  they grow →  enter bile ducts
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*The  prepatent  period is  10-12 weeks
      
==Treatment==
 
==Treatment==
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