Changes

====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. As with all nematodes the females are considerably larger than the males.  

==== Life-Cycle ====

==== Life-Cycle ====

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 presence of larvae in lungs can lead to diffuse [[Lungs Inflammatory - Pathology#Interstitial pneumonia|interstitial pneumonia]] with haemorrhage, [[Lungs Ventilation - Pathology#Atelectasis (Collapse)|atelectasis]], [[Lungs Circulatory - Pathology#Pulmonary oedema|interlobular oedema]] and [[Lungs Ventilation - Pathology#Emphysema|emphysema]]. 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.<br/>

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 presence of larvae in lungs can lead to diffuse [[Lungs Inflammatory - Pathology#Interstitial pneumonia|interstitial pneumonia]] with haemorrhage, [[Lungs Ventilation - Pathology#Atelectasis (Collapse)|atelectasis]], [[Lungs Circulatory - Pathology#Pulmonary oedema|interlobular oedema]] and [[Lungs Ventilation - Pathology#Emphysema|emphysema]]. 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.<br/>

'''Adults'''<br/>

'''Adults'''<br/>

Adult worms reproduce in the smill intestine of pigs.  

Adult worms reproduce in the smill intestine of pigs. The females are able to produce up to 200,000 eggs per day for a period of 9 months.

==== Pathogenesis ====

==== Pathogenesis ====

*These 'carrier sows' are epidemiologically important as they contaminate the farrowing house with eggs, thereby providing a source of infection for the susceptible piglets.

*These 'carrier sows' are epidemiologically important as they contaminate the farrowing house with eggs, thereby providing a source of infection for the susceptible piglets.

==== Epidemiology ====

===In Cows===

*Infection is only by ingestion of embryonated eggs.

Calves housed where infected pigs had previously been housed are susceptible to ''A. suum'' infection which can lead to the development of sever pneumonia.

*Adult worms produce 200,000 eggs per day which persist in the environment.

*Development of eggs is temperature-dependent and therefore seasonal.

*Carrier sows contaminate the farrowing house.