The hygiene hypothesis states that the human body is actually a massive ecosystem that is now at great danger due to a fast-diminishing number and types of microscopic organisms that live inside our bodies and in the environment around us. From a genetic perspective, this change in the environment has come so quickly that our bodies have not yet managed to adapt themselves to the changes. As a result, immunological disorders and autoimmune diseases have emerged.

Various concepts and therapies such as practical immunotherapies, helminthic therapy and probiotics have originated from the hygiene hypothesis.

The hygiene hypothesis is a theory which is the basis of practical immunotherapies and helminthic therapy. The hygiene hypothesis states that being in insufficient contact with infectious microorganisms can cause our immune system to fail. Under normal conditions, our body's immune system has to fight off bacterial, fungal, viral and parasitic threats by the thousands, and this constant battle serves as 'training' for the body, hardening its built-in defenses. However, in this modern era, due to the immense breakthroughs in the medical world which has led to widespread use of vaccines and numerous other types of medications, the human body's immune system has been weakened as a result of not being to fight against a sufficient number of against invasive organisms.