The use of parasitic worms as a treatment or preventive measure for conditions such as asthma, allergies, Alzheimer's and MS is being investigated.
Due to modern hygiene in the developed world, helminths, or parasitic worms, have largely disappeared from humans. This process, experts believe, has led to us losing the ability to regulate our immune system which, in turn, is linked to a rise in a range of disorders. Other factors may include changing diets and environmental pollution.
A proposed trial in Nottingham would see asthma sufferers infected with hook worms to see if their symptoms are eased. Elsewhere, an Argentinean study which found that people with MS who naturally became infected with worms and saw the progress of their disease slow down is being followed in the USA.
There are also hopes that drug companies will look at treatments that ape the effects of worm infections on the immune system.
Graham Rook, Professor of Medical Microbiology at University College London, said: "Certain organisms that were there throughout our evolutionary history have developed a role in causing the immune system to develop and causing the policemen of the immune system to be operating at the right level.
"The modern changes in lifestyle - not just modern hygiene - starting in the early 19th century, have led to a gradual withdrawal of these organisms."
Studies have also looked at whether pig whipworm eggs - also called trichuris suis - can be used to treat Crohn's disease in humans. Other conditions that may be linked to problems with the regulation of the immune system include depression, Alzheimer's disease and some cancers.