“In some ways disease does not exist until we have agreed that it does, by perceiving, naming, and responding to it,”
– Charles E. Rosenberg
So many of us are now used to live with scientific myths. One of them is, with modern science development, we have been gifted secured hygiene tools. But if you read latest research on The hygiene hypothesis, it postulates that an environment with a high incidence of infectious diseases protects against allergic and autoimmune diseases, whereas hygienic surroundings increase the incidence of these disorders. Read on.
Ever since modern medicine has waged war against bacteria and viruses, using their dumb weapons like antibiotics and antiviral chemicals, world has seen gradual decrease in occurrence of deadly infectious diseases.
War victory! Good, right?
Further, same data points suggests that while infectious diseases occurrence is reduced, occurrence of immune system disorders like Type 1 diabetes , Asthma, Multiple sclerosis and Crohn’s disease, have increased significantly.
Moreover, countries whom you consider DEVELOPED show higher trend of immune system disorders. Oh yeah, development side effects! Epidemiologic data provide strong evidence of a steady rise in the incidence of allergic and autoimmune diseases in developed countries over the past three decades. 
In fact, due to overuse of dumb weapons like antibiotics and antiviral chemicals, not so surprisingly, intestinal colonization with gram-negative bacteria, for instance, occurs later in developed than in less-developed countries, both quantitatively and qualitatively . And if you don’t know, early intestinal colonization by friendly bacteria is very critical for physical and mental growth of a child.   
For your surprise, countries/regions not affected by so called globalization of life style, do not suffer much from immune system disorder. Common and layman will respond that it is because in less-developed countries, all cases are not reported. Well, then you must study what biologists are saying about UNDERLYING MECHANISMS before passing general statement.
Biologists are saying that infection is good for us! Infections protect against allergic and autoimmune diseases. The term that they use is ‘antigenic competition’. Antigenic competition, in which the immune response to an antigen is decreased by a concomitant immune response against an unrelated antigen.  Story of this Antigenic competition starts when married couples decide to have baby. The transfer of maternal antiviral antibodies to newborns may also have a role in the susceptibility to autoimmune diseases. Decreased exposure of women to particular viruses before pregnancy may subsequently reduce the degree of protection against these viruses afforded to their newborns  Exposure to these viruses could provoke an immune response in the children that could ultimately lead to an autoimmune disease. This hypothesis could apply to the development of type 1 diabetes, in which rubella virus and coxsackie B virus have been implicated. Now imagine our educated urban middle class young females, influenced by western life style and bombarded by TV ads, using tons of antibacterial chemicals, taking antibiotics for trivial cold and fever, using toxic cosmetics….what should we expect from future mothers?
One more example: Hay fever or Allergic rhinitis, is an allergic inflammation of the nasal airways. Excess nasal secretion), itching, and nasal congestion and obstruction. Nasal allergy may cause recurrent sinusitis because of the obstruction to the sinus Ostia. It may lead to the formation of nasal polypi. Nasal allergy can result in serious otitis media and orthodontic problems. Patients of nasal allergy have four times more risk of developing bronchial asthma.
Number of people in the U.S. who have either allergy or asthma symptoms: one in five.
Percentage of the U.S. population that tests positive to one or more allergens: 55%.  Same stats is true in metros and tier 2 cities of India, under the influence of massive and mindless urbanization.
But farmers in my village, despite living in so called hell full of pollens, rarely experience this condition. And this is worldwide true for communities living close to nature.
In short, there is a certain irony in the fact that we must now search for new ways to reproduce the infectious diseases against which MODERN MEDICINE have been fighting with great success over the past three decades. Whom you consider as developed countries are nothing but nations living on continuous confused, chaotic and self-centered trial and error methods about standard of living. On the other hand, when we talk about Manu and his smriti prescribing certain code of conducts, we either laugh on them or ignore considering them as ancient, designed for some ancient civilization.
Seriously, we need to relook to our scriptures, including Ayurveda and start re-designing life styles. Otherwise, Type 1 diabetese and asthama like immune system disorders are here to stay with us.
The philosophical result of chemical medicine’s success has been belief in the Technological Fix. Drugs became the best or only valid treatments for all ailments. Prevention, nutrition, exercise, lifestyle, the patient’s physical and mental uniqueness, environmental pollutants—all were glossed over.
No one who’s seen the decline of pneumonia and a thousand other infectious diseases, will deny the benefits of technology. But, as most advances do, this one has cost us something irreplaceable: Degenerative diseases— heart attacks, arteriosclerosis, cancer, stroke, arthritis, hypertension, ulcers, and all the rest—have replaced infectious diseases as the major enemies of life and destroyers of its quality.
The failure of technological medicine is due, paradoxically, to its success, which at first seemed so overwhelming that it swept away all aspects of medicine as an art.
Keep aside your intellectual arrogance, have faith in nature, read Manu Smriti (and other scriptures), unveil ageless hints, do research, find truths behind instructions, design solutions in present context like start nurturing gau mata (desi cows), start using cow-dung, urine for basic cleanliness and discard all foolish weapons against so called enemies i.e. bacteria and viruses.
 Adlerberth I, Carlsson B, de Man P, et al. Intestinal colonization with Enterobacteriaceae in Pakistani and Swedish hospital-delivered infants. Acta Paediatr Scand 1991;80:602-10.
 http://goo.gl/RQKDYo (Google book link for ADVANCES IN IMMUNOLOGY, Volume 18)