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Ecological association between scarlet fever and asthma
1Unidad de Investigación Médica en Epidemiología Clínica, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Avenida Cuauhtémoc 330, CP 06720, México DF, México. mhvargasb@yahoo.com.mx
Respiratory Medicine
|June 11, 2005
Summary
The hygiene hypothesis suggests infections reduce allergies. This study found a strong inverse relationship between asthma and scarlet fever, indicating Streptococcus pyogenes may play a role in allergy development.
Area of Science:
- Epidemiology
- Immunology
Background:
- The hygiene hypothesis proposes reduced infection exposure increases allergy prevalence.
- Evidence linking specific infectious diseases to asthma is limited and conflicting.
Purpose of the Study:
- To investigate the ecological association between asthma and scarlet fever trends.
- To evaluate the relationship across annual, seasonal, and geographic patterns.
Main Methods:
- Ecological analysis of national trends in asthma and scarlet fever (1996-2003).
- Spearman's rank correlation coefficient (r(S)) used to assess associations.
- Analysis conducted on annual, monthly, and state-level data.
Main Results:
- A significant inverse association was observed between asthma and scarlet fever annually (r(S)=-0.93, P=0.0009).
- Seasonal analysis revealed differing peak periods for asthma (Sept-Jan) and scarlet fever (Mar-Jun), with a negative correlation (r(S)=-0.84, P=0.0006, 1-month lag).
- Geographic analysis across Mexican states showed higher scarlet fever incidence correlated with lower asthma incidence (r(S)=-0.47, P=0.007).
Conclusions:
- Scarlet fever and asthma exhibit a strong inverse relationship, supporting the hygiene hypothesis.
- Streptococcus pyogenes, the cause of scarlet fever, is a potential factor in immune system modulation relevant to asthma.
- Further research is warranted to explore the role of Streptococcus pyogenes in the context of the hygiene hypothesis.