Shortcomings of the Hygiene Hypothesis
The hygiene hypothesis, as initially proposed by Strachan in 1989, traced the supposed reduction in exposure to microbes during childhood to the rise in the incidence of allergic and autoimmune disease.
However, this theory is unable to explain several factors about the epidemiology of allergic disease including:
- Why allergic asthma is on the rise in American cities class as ‘unhygienic’.
- Why migrant children in some large European cities have a lower incidence of allergic disease despite sharing many common characteristics as to the environment.
- Why infection by airborne viruses does not seem to protect from allergic sensitization.
- Why research has not shown congruent findings to support the link between certain viral infections and allergic diseases in diverse populations.
- The inefficiency of probiotics in the prevention and treatment of allergic diseases.
As a result of these factors, there is a need to reconsider the basis of the hygiene hypothesis and identify particular microbial agents. That may play a protective role in the prevention of allergic diseases.
Microbial Diversity
The microbial diversity, also known as the “high turnover and diversity hypothesis”, was first proposed by Paolo Matricardi, and later refine by von Herzen.
It suggests that a high turnover of bacteria at the mucosal level, locate in the lymphoid tissue of the nasal tubes, bronchi and gut, is the predominant state of https://ufabet999.app the normal body. This is in contrast to the supposed static colonization by particular species. This wide and changing variety of bacteria causes the presentation of many strong antigens to the immune system. Resulting in its incessant stimulation. This is thought to have a protective effect against atopic and allergic diseases.
Some research has supported this notion. Although the sample size was small and further studies are required to validate the hypothesis. It remains unclear if the protective effect is brought about by diversity alone, or by a diverse population. Which encompasses particular organisms that are necessary for the development of the immune system.