Before the advent of good hygiene practices and successful antimicrobial agents, the rate of communicable disease was unimaginable compared to today's rate of disease. Comparatively, it is easy to see a difference in sanitary standards between the western and industrialized nations and the third world and non-developed nations. Additionally, the rate of communicable diseases, such as diarrheal and parasitic diseases, is far more prevalent in the third world and underdeveloped communities. However, the rate of autoimmune and allergic disease is far more prevalent in developed nations compared to the third world. In fact, allergic and autoimmune disease is almost unheard of among underdeveloped nations; but what is the catalyst behind the growing quantity of autoimmune and allergic disease in the industrialized world? The answer to this question my be found in the ever growing theory of hygiene hypothesis.
Simply put, hygiene hypothesis declares that infants and children growing up in very clean, and sometimes near sterile, households are prevented from contracting many common parasitic and pathogenic illnesses. This underexposure prevents those children from developing proper immune responses to common environmental agents. These improper immune responses cause common allergies, also known as hay fever. In the end, one question lingers: has the amount of over exaggerated cleanliness, coupled with the immense overuse of antimicrobial cleaners, medication, and disinfectants, seen in developed nations, had a significant, and direct, effect on the allergic and autoimmune disease rates? Additionally, is there such a thing as too clean? If so, what can we do to ensure the proper development of immunity in future generations?.
The influx of hay fever and other allergic diseases began to increase steadily after the industrial revolution, and by the 1950's, the medical community began to take notice.