Vladimir Bencko1* and Petr Šíma2
1Institute of Hygiene and Epidemiology, 1st Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
2Institute of Microbiology, Academy of Sciences of Czech Republic, Prague, Czech Republic
An important contribution to understanding the causes of the increasing incidence of allergic, atopic and other immunopathological conditions in the pediatric population and, later on increased incidence of non-communicable diseases (eg., Type 2 diabetes, and autoimmune diseases) in adulthood was the hygiene hypothesis. Key risk factors relating to the hypothesis was that children population has inadequate exposure to antigens in the environment, cool chain hypothesis, and infectious agents in the context of antibiotics overuse, urban life-style excessively meticulous daily care of children and high standard of household hygiene. As protective factors were taken such as breastfeeding, family size and sibling relationships, that is life in a larger family. The literature generally states that the reduced exposure to microbial antigens in children probably plays an important role in the growth and incidence of allergies and immunopathological disorders in child and adolescent populations. Strenths of the data supporting data for each of these risk or benefit factors vary considerably. The most promising factors that could be causally associated with the development of allergies include exposure to intestinal microbiome, breastfeeding and sibling factors. However, most studies in this area suffer from serious methodological flaws, particularly the reliance on retrospective recall the requested information, making it difficult to determine the validity of the "hygiene hypothesis". However, the "hygiene hypothesis" as well as follow-up the "old friends hypothesis”, are based on knowledge of the critical impact of the intestinal microbiome to the maturation of the immune system of children are an important area of research, which could provide clues to understanding the causes of the current adverse developments in the incidence of allergies, including atopy as well as eg. chronic autoimmune, inflammatory bowel disease not only in children but at a later age also the population of adolescents and adults.
Hygiene hypothesis; Exposure to antigenic stimuli; Cold chain hypothesis; Overuse of antibiotics; Old friends hypothesis; Breast feeding
Bencko V, Šíma P. Incidence of Allergy and Atopic Disorders and Hygiene Hypothesis. Clin Oncol. 2017; 2: 1244.