Clinical Neurology

Worms For Immune Regulation in Multiple Sclerosis (WiRMS) trial

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The WiRMS (Worms for Immune Regulation in Multiple Sclerosis) trial is, to our knowledge, the first trial of controlled exposure to the human parasite hookworm (Necator americanus) for the treatment of MS, and only one of 3 worm helminth therapy trials in the world. It takes advantage of expertise unique to the University of Nottingham. (See press release about the trial.)

Lead researchers

  1. Professor David Pritchard (School of Pharmacy) is a world renowned immunoparasitologist and who has pioneered the use of helminths for modulation of inflammatory diseases and the concept of “drugs from bugs”
  2. Professor Cris Constantinescu (School of Medicine) is a clinical neuroimmunologist with expertise in multiple sclerosis and other immune-mediated neurological diseases, who also has formal training in immunology and experience in MS immunology and immunoparasitology. 

Rationale and presumed mechanisms

According to the hygiene hypothesis or to the "old friends hypothesis", eradication of parasites such as hookworms in the Western world has led to a surge in inflammatory diseases that were previously kept in check by the human-worm coexistence.

Whether this hypothesis is true or not, the fact is that the hookworm does produce substances that dampen the immune response of the host without suppressing it altogether, ensuring a peaceful coexistence.

In a group of people with MS from Argentina who were naturally infected with gut parasites, the disease was much milder. This may be down to a type of cells that are triggered by the parasites, the regulatory T cells, whose mission is to keep inflammation under control and to prevent autoimmune diseases. Another mechanism may be parasite-induced changes in the gut flora.

Trial details

We aim to recruit 72 patients with relapsing–remitting MS or secondary progressive MS with superimposed relapses.

They will visit the MS Clinical Trials Unit at the Queen's Medical Centre, Nottingham, be randomised to receive either 25 larvae (babies) of hookworm (they are microscopic so cannot be seen with naked eye) or a dummy treatment (placebo).

Roughly monthly, they will have a neurological examination and immunology blood tests. From month 3 on, they will have monthly MRI scans, performed at the University of Nottingham Imaging Facility, until month 9, when they will receive a medicine to eradicate the worms. They will then have a final visit and MRI scan at month 12.

Neither the study participants nor the doctors will know their treatment (double-blind) until all participants have finished the study and data are analysed.

The participants will then be informed of the results of the study and also of which treatment they had been on.

For any questions, or if you wish to participate in the study, please contact:  

Tel: 0115 748 4077






Clinical Neurology

School of Medicine
The University of Nottingham
C Floor, South Block, Queen's Medical Centre Nottingham, NG7 2UH

telephone: +44 (0) 115 823 1441
email:Group Administrator