RT Book, Section
A1 Davis, Carla M.
A1 Chatila, Talal A.
A2 Kline, Mark W.
SR Print(0)
ID 1182931734
T1 Allergic Disease and Atopy
T2 Rudolph's Pediatrics, 23e
YR 2018
FD 2018
PB McGraw-Hill Education
PP New York, NY
SN 9781259588594
LK accesspediatrics.mhmedical.com/content.aspx?aid=1182931734
RD 2024/04/23
AB A  precipitous  increase  in  incidence  and  prevalence  of  allergic  diseases  in  the  last  50  years  has  led  to  the  current  pandemic  proportions.  In  some  subpopulations,  as  many  as  1  in  4  children  suffers  from  asthma,  and  up  to  1  in  12  has  a  food  allergy.  One  explanation  for  this  dramatic  increase  in  allergic  diseases  is  the  “hygiene  hypothesis,”  which  posits  that  a  decrease  in  the  exposure  to  microbes  due  to  improved  hygiene,  smaller  families,  less  breastfeeding,  more  immunizations,  and  lack  of  serious  childhood  infections  results  in  altered  immunoregulation  and  deviation  toward  an  allergic  disease-promoting  T-helper  cell  2  (TH2)  response.  Microbial  exposure  promotes  the  production  of  regulatory  T  cells  involved  in  maintaining  tolerance  to  allergens.  Lack  of  sufficient  microbial  exposure  may  result  in  weakened  tolerance  and,  in  the  setting  of  other  factors  such  as  genetic  predisposition  and  environmental  exposures,  result  in  the  promotion  of  allergic  diseases.  The  important  environmental  exposures  that  can  directly  decrease  microbial  diversity,  causing  increased  expression  of  atopy,  include  urbanization,  industrialization,  climate  change  and  rising  temperatures  with  prolonged  pollen  seasons,  increased  viability  of  mold,  and  increased  aeroallergen  exposure.  The  increased  prevalence  of  allergic  disease  is  directly  related  to  these  factors.