Ascariasis

The term Ascariasis refers to disease caused by nematode worms of the genus Ascaris. This disease can occur in a number of different species as described below.

In Pigs

Ascaris suum is the primary cause of ascariasis in pigs.

Diagnosis

The disease is most commonly identified by the presence of milk spots on the liver. This is usually an incidental finding at post mortem or during the slaughter process. The discovery of milk spots on the liver will lead to the comdemning of the infected tissue.

Gross Examination

In the early stage of the disease haemorrhagic tracts will be visible through the liver due to the migratory activity of the larvae. In later stages of the disease diffuse white spots on the capsular surface of the liver will be visible due to the fibrosis of these tracts.

Microscopic Examination

The early disease will show haemorrhage and necrosis of parenchyma along the tracts created by the migrating larvae. There will be fibrosis at these sites in the later disease as well as evidence of inflammatory response. The inflammatory response consists of infiltration of many eosinophils, as well as lymphocytes and macrophages.