It is known that worms are ‘old infections’ and that old infections tend to manipulate their host’s immune system to their advantage – they use the immune system to hide from attack by the immune system. It is not altogether surprising, then, that worms can affect non-infective diseases. Previous research has shown infections protecting people from atopy. Now it turns out that worm infestation might also offer protection against inflammatory bowel disease. One possibility is that they do this by altering intestinal flora and reducing the load of bacteria that promote infection.  Certain people who are predisposed to inflammatory bowel disease might gain protection from worm infestation.
— Richard Lilford, CLAHRC WM Director
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- Leslie M. Parasitic worms may prevent Crohn’s disease by altering bacterial balance. Science. 24 April 2016.