High intensity of helminth (parasite) infection can reduce allergy

Atopy, the genetic predisposition of one’s immune system to become sensitised to allergens, is an important risk factor for allergic disease. The hygiene hypothesis suggests that infection by helminths (parasites) can reduce atopic responses, and studies with animal models have shown that the success of the protective factor depends upon the intensity of the parasitic infections.

An overview of several studies has indicated that in areas with a high prevalence of helminths, the risk of allergy is decreased, whereas where helminthic infection is low, the risk of allergy is increased.

A study to test this hypothesis has been carried out by scientists at the universities of Harare, Zimbabwe and Edinburgh, Scotland They focused on two Zimbabwean villages, each with a population with a different rate of infection of the parasite Schistosoma haematobium: one village (365 people) with high helminthic transmission and one village (307 people) with low helminthic transmission.  They measured allergic reactivity, to the common house dust mite within the populations, with a skin prick test.

The scientists found that in the village of high intensity infection rates, reactivity levels were inversely related to infection rates - that is, where infection intensity was high, reactivity was low. However, in the village where infection intensity was low, there was no correlation between allergic responses and infection intensity.

The scientists concluded that the relationship between helminth infections and allergic reactivity, where the helminth is the parasite Schistosoma haematobium, is dependent on the intensity of the current infection. This correlates with the animal models to show that in humans with increased parasite burdens on their bodies, the immunoregulation of immune responses to allergens becomes more pronounced – that is, their allergies are fewer.

Source: The International Archives of Allergy and Immunology

That may well be a very interesting study, but the parasite Schistosome is not suitable for use in helminthic therapy.

For practical use of helminths to reduce allergy, John Scott’s article has some useful information - 2009

Helminthic therapy is what has emerged in recent times since the creation of the hygiene hypothesis in the 19th century. The hygiene hypothesis developed from the understanding that being too clean is not necessarily a positively healthy situation for the body – in fact too much cleanliness may well have wiped from our bodies the beneficial and benign ‘old friends’  - bacteria and parasites - that evolution has taken thousands of years to bring into perfect balance within our bodies.

These disappeared ‘old friends’ need to be replaced – and they include beneficial bacteria  (such as probiotics – an ‘on trend’ modern supplement) and parasites such as the human hookworm Necator americanus and the human whipworm Trichuris trichiura. None of the worms cause any disease in man at the dosage levels recommended for therapy, none of them can reproduce inside a human, and none of them can pass easily between people.

Helminthic therapy has already been shown to improve conditions such as allergies, asthma, diabetes (type 1), ulcerative colitis, Crohn's disease, and multiple sclerosis, and leaving aside the ‘gross factor’ of how one gets the worm into one’s body, helminthic therapy is very straight forward. Compared to treatment of conditions with drugs, controlled helminthic therapy is fast-acting, long-term and has no serious side-effects.

Although helminthic therapy is not available on the NHS, you can ask your doctor for a referral to the treatment at Nottingham where hookworm larvae are available. You may have to include a note saying you are willing to be absolutely responsible for any adverse outcome – though an adverse outcome is unlikely.

Alternatively, if you can afford it, you can obtain the larvae or ova privately. See John Scott’s full article for much more information.


Click here for more research on worms

First Publishd March 2012

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