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Submitted to: Pig Progress
Publication Type: Trade Journal Publication Acceptance Date: 10/12/2003 Publication Date: 12/15/2003 Citation: Urban Jr, J.F. 2003. Impact of ascaris suum. Pig Progress. 3-27. Available: http://www.agriworld.nl. 23-27 Interpretive Summary: Technical Abstract: The immune tools needed to combat an infection with the large round worm, Ascaris suum, are much different from those needed against bacteria, viruses and protozoan parasites. Migrating A. suum larvae and adult worms are extra cellular parasites that selectively trigger pig immune cytokines that stimulate the development and activation of large numbers of eosinophils, basophils, mast cells and classes of antibody that bind to these cells. These cytokines also promote physiological changes in mucus production, smooth muscle contractility and epithelial cell transport in the intestine and lung. In addition, they reduce the synthesis of classes of antibodies that bind to and enhance the uptake of microbial pathogens by phagocytic cells leading to their destruction within the activated cell. Increasing levels of worm exposure will push the immune system towards an extreme that will limit its capacity to control intracellular pathogens. In contrast, pigs infected with the protozoan parasite, Toxoplasma gondii, which invade phagocytic cells and are often destroyed when these cells are activated, selectively stimulates pig immune cytokines geared toward the control of intracellular infection at the expense of cytokines that regulate immunity to worms. There is natural ying-yang plasticity to the immune system that sometimes makes it work inappropriately in response to a specific infection or dual infections. |
