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====Indentification====
====Indentification====
''Ascaris suum'' is a large roundworm of pigs, each worm can grow up to 40cm long.
''Ascaris suum'' is a large roundworm of pigs, each worm can grow up to 40cm long.
==== Life-Cycle ====
==== Life-Cycle ====
As with most ascarid species the larvae of ''Ascaris suum'' have a migratory life cycle moving through several body organs before becoming mature adults in the small intestine of the pig.
As with most ascarid species the larvae of ''Ascaris suum'' have a migratory life cycle moving through several body organs before becoming mature adults in the small intestine of the pig.
'''Eggs'''
'''Eggs'''
Eggs are shed in the feaces of the host and have a thick proteinacious coat that allows them to exist on pasture for extended periods of time, up to 4 years. The ability of eggs to survive on pasture for so long and being so
Eggs are shed in the feaces of the host and have a thick proteinacious coat that allows them to exist on pasture for extended periods of time, up to 4 years. The proteinacious coat allows this long survival on pasture and also makes the eggs extremely difficult to destroy with common disinfectants.
'''Larvae'''
The larval stages are migratory, moving through several organ systems before becoming adults. This is the stage of the parasite that is mainly responsible for the clinical signs of ''A. suum'' infection. The larvae hatches from the egg at the L2 stage, from here is migrates from the small intesting to the liver via the hepatic portal vein. Whilst migrating through the liver the larvae create heamorrhagic tracts, these are later repaired with fibrous tissue causing the appearance of '''milk spots'''. From the liver the larvae move to the heart and lungs where they cause the major clinical signs of ''A. suum'' infection. In the heart a high worm burden will seriously reduce the cardiac output and may also cause blockage which can be fatal. The larvae in the lungs will move up towards the treachea which will stimulate the coughing reflex and cause them to be coughed up into the pigs mouth to be reswallowed as adults into the gastrointestinal system.
*The larvae undergo hepato-tracheal migration before establishing in the small intestine. The damage they cause in the liver is known as 'white-spot' or 'milk-spot'.
*The larvae undergo hepato-tracheal migration before establishing in the small intestine. The damage they cause in the liver is known as 'white-spot' or 'milk-spot'.