There has been lots of interest recently in reports of using worms to treat Crohn’s disease. Not earthworms like you find in the garden, but worms which live in the intestine. The first to be used was a pig whipworm, which cannot live for more than a few weeks in humans, and therefore is not particularly dangerous, but more recently hookworms, which are a human pathogen. These live in the gut and feed on blood in the intestinal wall. A heavy infestation may lead to anaemia. These worms may get into the body if people walk barefoot over ground where the eggs have fallen (in faeces from an infected person!) and hookworm infestations were a major health problem amongst the poor population in southern states of the USA in previous years.
The importance of worms is that they provoke a different sort of immune response to that which occurs after bacterial infection. In scientific terms, they provoke a Th2 response, whereas the usual response is known as Th1. In Crohn’s disease, the immune attack on the bacteria living in the bowel is mediated by a Th1 response – so if you can switch it to Th2, the Crohn’s immune attack will be less and the disease will improve.
This is just what happens in pregnancy. Pregnant woman develop a Th2 response, and most find that their Crohn’s improves after 12 weeks or so into the pregnancy. Those controlling their Crohn’s by diet often find that they are able to eat foods which would usually upset them. After the baby is born, of course, they go back to the usual Th1 state and must keep strictly to their diets if they are to remain well.
So people who have Crohn’s may take a small number of hookworm eggs and many find that their disease improves. Unfortunately the effect wears off before very long. It would clearly be dangerous to give large numbers of hookworm eggs which might lead to a severe infestation., possibly even worse than the Crohn’s itself! So patients may find that they try to get by with repeated doses of 25 or 50 eggs. The difficulty that this causes is for those who are trying to control the Crohn’s by diet. Obviously the hookworms prevent the normal reactions to foods occurring, and so the patient can never be sure which foods to eat and which to avoid. If you are trying to treat your Crohn’s disease by diet, don’t be tempted by worms! The benefits are short lived and it seems instinctively wrong to try and treat one disease by causing another.
This article was first published on the original crohns.org.uk blog. Research has moved on since, so please check current advice with your IBD team.