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A to Z of MS Parasitic worms

Several studies have explored the role of parasitic worms in controlling the effects of multiple sclerosis. It is though that this may be linked to the hygiene hypothesis - the theory that a cleaner modern lifestyle means that cchildren are not exposed to infections, parasites and other environmental factors to the same degree as previously which leads to a susceptibility to a number of conditions.


The hookworm is a parasitic worm that lives in the small intestine of its host. Hookworm infection has been found to have beneficial effects on people with conditions linked to overactive immune systems, including asthma and Crohn's disease.

A small study in Argentina followed 12 people with multiple sclerosis who were infected with hookworms, 12 who were uninfected and a control group of 12 people who didn't have MS. Participants were followed for an average of four and a half years. In this time, there were three clinical relapses in the infected group, compared to 56 in the uninfected group. 11 of the uninfected group showed an increase in their EDSS score during the study, compared to two of the infected group.

The researchers suggest that the immune systems response to the hookworm infection causes a decrease in the normal inflammation associated with MS.

A UK study based at the University of Nottingham is currently recruiting people with relapsing remitting MS. The Worms for Immune Regulation of Multiple Sclerosis (WIRMS) study will infect people with a small number of hookworms and then monitor the effects on their MS over the following year.


The whipworm is a type of pasrasitic roundworm that hatches in the small intestine before moving as adults to the large intestine. Research has looked at whipworms in the treatment of a number of conditions including Crohn's disease, ulcerative colitis and autism.

A small study in five people with relapsing remitting MS treated over three months found favourable trends were seen in MRI scans and in measures of cells in the immune system.


In 2014, Australian researchers identified a molecule (called AcK1) in parasitic worms that reduces immune system activity. This may lead to treatments for autoimmune conditions such as MS that don't require ingesting actual worms.


Conradi S, et al.
Environmental factors in early childhood are associated with multiple sclerosis: a case-control study.
BMC Neurology 2011;11:123.
read online

Correale J, Farez M.
Association between parasite infection and immune responses in multiple sclerosis.
Annals of Neurology 2007;61(2):97-108.

Worms for Immune Regulation of Multiple Sclerosis (WIRMS) study
Clicinal Trials website

Recruitment starts on MS hookworm trial
Nottingham University news item - 29 Feb 2012

Fleming JO, et al.
Probiotic helminth administration in relapsing-remitting multiple sclerosis: a phase 1 study.
Multiple Sclerosis Journal 2011;17(6):743-754.

Chhabra S, et al.
Kv1.3 channel-blocking immunomodulatory peptides from parasitic worms: implications for autoimmune diseases.
FASEB Journal 2014 Jun 2. pii: fj.14-251967. [Epub ahead of print]

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