Modern medicine may have stopped short of blood-letting, leeches and purges but parasitic worms could be making a come-back!
Medical scientists are considering the use of parasitic hookworms to treat patients with asthma.
The researchers hope the worms may even prove to be effective against conditions such as Crohn's disease, hay fever and multiple sclerosis (MS), all conditions in which the immune system appears to overreact.
This line of research has come about as a result of scientists noting that diseases such as Crohn's and MS do not seem to affect people in regions such as Ethiopia where the worms are endemic.
They suspect that the worms tone down the inflammatory part of the body's immune response and may therefore help counteract the symptoms of such diseases.
Professor David Pritchard at the University of Nottingham says when people have hundreds in their gut it can lead to iron deficiency and anaemia, but small doses of the 1.5cm worms may be useful as a treatment for immune diseases.
Professor Pritchard's team have carried out two small trials in order to establish what dose of the worms would be safe for patients.
They say so far the results, though far from conclusive, are encouraging.
The tests were carried out for safety rather than efficacy, and Professor Pritchard says that many of the patients in the hay fever trial had opted not to have the worms removed with tablets at the end because they had seen an improvement in their symptoms.
Tests on the hay fever sufferers confirmed that the hookworms stimulate the body to produce white blood cells called regulatory T-cells, that dampen down the immune response.
The team is now about to embark on a larger trial in patients with asthma to work out whether the hookworms actually diminish symptoms.
The worms cannot reproduce inside the body and are eradicated with tablets.
The initial results were presented to the British Association for the Advancement of Science's conference in York.
Professor Pritchard says if a map of where hookworms are found is superimposed it can be seen that asthma and hookworms appear to be mutually exclusive, and Crohn's disease too seems to be a disease of the developed world.