We are not alone.  With the first successful sequencing of the human genome came the startling discovery that  we are merely 10% human on a cellular level. The remaining 90% is made up of the organisms found in our biome; “the ecological community of commensal, symbiotic, and pathogenic microorganisms that literally share our body space.” (Joshua Lederberg).

It has become increasingly appreciated since this discovery that the role of our immune system is not simply to ward off unwanted bacteria and pathogens, but also to learn to accept and tolerate the commensal and symbiotic organisms of the human biome that are non-self but that we depend upon to function.  Like any ecosystem,  our bodies must achieve the right diversity and balance in order to maintain good health.

Helminth worms have been present in the intestines of vertebrates since long before the evolution of homo sapiens. The oldest known evidence of a helminth colonization has been found in a 270 million year old shark coprolite from the Paleozoic period. Given that humans are estimated to have first walked the earth a mere 200,000 years ago, it would be safe to assume that helminth worms have been our companions since the very birth of humanity.

Throughout the world today, helminths are still very common. It is estimated that  2 billion people are currently playing host to at least one helminth species and approximately three quarters of a billion people are carrying hookworms.

Until the 20th century hookworms were endemic throughout most of the world. Recent history however has seen the introduction of modern sewerage systems and medical advances which have all but eradicated hookworms in post industrial westernised society in the space of just a few generations.

Over the same time period, immune dysfunction has become an epidemic in the developed world.  It is estimated that in the USA up to 50 million Americans now suffer from one or more of 80 – 100 known autoimmune diseases (by comparison, cancer affects up to 9 million and heart disease 22 million in the USA). In Europe the rate of allergy is increasing by 5% every year and it was estimated that in 2015 one half of the entire European population suffered from at least one allergy.

By contrast incidence of immune dysfunction in the developing world has remained minimal and static, just as it was in the industrialized world a mere 100 years ago.

What is the cause?

Since 1989 a theory known as the Hygiene Hypothesis/Old Friends Theory has gained support in the scientific community.  It states that our modern sanitized environment has led to a lack of microorganisms and symbiotic helminth worms in the human biome. These organisms are seen as necessary to regulate the body’s immune system and without them incidence of immune dysfunction and allergic and inflammatory disease has increased to epidemic proportions.

The hypothesis is grounded in epidemiological data that shows a clear inverse correlation between helminth infection and immune disorders throughout the world, as can be seen in the maps below:

Global prevalence of Soil Transmitted Helminths


  (Source: World Health Organisation)

Global prevalence of Inflammatory Bowel Disease


(Source: BMJ Publishing Ltd & British Society of Gastroenterology)

Global prevalence of Asthma


 (source: BBC News)

Global prevalence of Allergic Rhinitis

allergic rhinitis

(source: InQpharm Internal Market Research NASYA)

Global prevalence of Multiple Sclerosis



Global prevalence of Celiac Disease


(Source: Annual Review of Immunology Vol. 29)

Global prevalence of Type 1 Diabetes


(Source: ‘Helminth Infection and Type 1 Diabetes’ Zaccone P. & Hall SW., 2012)


Additionally, migration studies have shown that recently arrived immigrants into the developed world who have had no previous history of immune dysfunction are likely to develop immune disorders in relation to the length of time since arrival, and their offspring go on to experience equal incidence of immune dysfunction as natives of the host nation. This observation rules out the possibility that the cause is purely genetic and suggests environment as the major factor.

Modern sanitized living has massively reduced the number and variety of organisms living within us with whom we have evolved to coexist.  These organisms train and modulate our immune system and their sudden eradication in our environment over the last few generations has left us in a state of imbalance that our bodies have been unable to adapt to.  The consequence of this absence can be seen in the modern epidemic of allergic and autoimmune disorders in post industrial society.

“Parasites have evolved to damp our immune responses so that they can stay in our bodies. Our immune system evolved to expect parasites to damp it. So in a world with no parasites, it behaves like a person leaning into the wind when it drops: The system falls over.”  Matt Ridley, from a review of “An Epidemic of Absence” by Moises Velasquez Manoff in The Wall Street Journal.

The hygiene hypothesis/Old Friends Theory is now a commonly accepted theoretical model used by immunologists and epidemiologists studying allergic disorders all over the world.

So what can be done?

The obvious answer is to replace the helminth worms that our bodies are lacking in order to redress the balance. If we can allow their influence to gently rein in and modulate our over-active and misdirected immune systems, we can once again achieve the equilibrium that has been lost due to modern living conditions.

 The startling success of using hookworm and other helminths to treat immune dysfunction has led to the rise of Helminthic Treatment which is now being used by a growing number of people willing to try an experimental dose of worms to reduce allergic, inflammatory and autoimmune sypmtoms.

Hookworms can gently and safely modulate an out of control immune system so that sufferers of many allergic, inflammatory and autoimmune conditions can achieve relief from their symptoms and become less reliant on conventional pharmaceutical drugs.