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A modern miasma hypothesis and back-to-school asthma exacerbations.
MedLine Citation:
PMID:  20869177     Owner:  NLM     Status:  In-Process    
Abstract/OtherAbstract:
A sudden increase in the rate of asthma exacerbations has been observed among young children in many countries 2-3 weeks after their return-to-school following the summer holidays. These exacerbations are frequently associated with human rhinovirus (hRV) infections, with possible interactions with allergen sensitisation, allergen exposure and medication use. It was originally proposed that the sudden increase resulted from new strains of respiratory viruses acquired during the holidays spreading rapidly on return to school. While there is compelling evidence implicating hRV in these exacerbations, recent observations on virus transmission, infection patterns and immune responses to both viruses and allergens have led us to propose an additional hypothesis for this increase in exacerbations. We propose that classrooms typically provide persistent exposure to a mixture of airborne viruses, viral proteins, endotoxin, community allergens and other human-derived aerosols - a modern miasma. During the preceding school term, this exposure establishes and maintains a level of immune tolerance and herd immunity, which then declines during the two-month holidays due to lack of such exposure, creating a transitory window of susceptibility to viral infections and asthma. The return to school re-establishes exposure to these aerosols resulting in an acceleration of exacerbations, until the tolerance and herd immunity are re-established. Thus, the peak in return-to-school asthma is more a function of a transitory increase in susceptibility due to a temporary lack of this complex exposure, than it is to novel, locally endemic strains of hRV.
Authors:
E R Tovey; W D Rawlinson
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Medical hypotheses     Volume:  76     ISSN:  1532-2777     ISO Abbreviation:  Med. Hypotheses     Publication Date:  2011 Jan 
Date Detail:
Created Date:  2010-12-20     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7505668     Medline TA:  Med Hypotheses     Country:  United States    
Other Details:
Languages:  eng     Pagination:  113-6     Citation Subset:  IM    
Copyright Information:
Copyright © 2010 Elsevier Ltd. All rights reserved.
Affiliation:
Allergen Group, Woolcock Institute of Medical Research, Missenden Road, Glebe, NSW 2050, Australia. ert@med.usyd.edu.au
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