Too clean, or not too clean: The Hygiene Hypothesis and home hygiene

London School of Hygiene and Tropical Medicine, London, UK.
Clinical & Experimental Allergy (Impact Factor: 4.77). 05/2006; 36(4):402-25. DOI: 10.1111/j.1365-2222.2006.02463.x
Source: PubMed


The 'hygiene hypothesis' as originally formulated by Strachan, proposes that a cause of the recent rapid rise in atopic disorders could be a lower incidence of infection in early childhood, transmitted by unhygienic contact with older siblings. Use of the term 'hygiene hypothesis' has led to several interpretations, some of which are not supported by a broader survey of the evidence. The increase in allergic disorders does not correlate with the decrease in infection with pathogenic organisms, nor can it be explained by changes in domestic hygiene. A consensus is beginning to develop round the view that more fundamental changes in lifestyle have led to decreased exposure to certain microbial or other species, such as helminths, that are important for the development of immunoregulatory mechanisms. Although this review concludes that the relationship of the hypothesis to hygiene practice is not proven, it lends strong support to initiatives seeking to improve hygiene practice. It would however be helpful if the hypothesis were renamed, e.g. as the 'microbial exposure' hypothesis, or 'microbial deprivation' hypothesis, as proposed for instance by Bjorksten. Avoiding the term 'hygiene' would help focus attention on determining the true impact of microbes on atopic diseases, while minimizing risks of discouraging good hygiene practice.

Download full-text


Available from: Sally F. Bloomfield, Jul 15, 2014
25 Reads
  • Source
    • "The reason for this apparent increase may be due to increased awareness and diagnosis of UC. Besides, improved access to a cleaner environment and the resulting decreased bacterial infection in children may also contribute to this change 7, 8. Therefore, the microbial in human gut may play a pivotal role in the pathogenesis of UC. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Aims: To investigate the association between H. pylori infection and UC prevalence in China. Materials and methods: Subjects were selected from patients admitted in Department of Gastroenterology for abdominal pain, hematochezia, diarrhea and other GI symptoms during 2009-2012. UC diagnosis was based on both colonoscopy and biopsy. H. pylori detection was based on (14)C urea breath test (UBT) and biopsy sample culture. Patients' demographic, anthropometric and serologic data were selected. H. pylori infection rate was compared between UC and control groups, followed by a subgroup analysis on the association between H. pylori infection and extent and severity degree of UC. Results: Totally, 153 and 121 patients were selected and divided into UC and control groups. There were no significant differences in age, gender, BMI, hypertension and diabetes. However, smoking history was significantly lower while WBC and CRP levels were significantly higher in UC group. The H. pylori infection rate in UC group was 30.5%, significantly lower than that of 57.0% in control group. The H. pylori infection rate in UC of left colon and whole colon were 33,9% and 24.2% (p<0.05 between them), both significantly lower than that in control group. In addition, the H. pylori infection rates in mild, moderate and severe UC subgroups were 37.8%, 32.3% and 22.2% (p>0.05 among them), all of which were significantly lower than that in control group. Conclusion: We reported a significantly lower H. pylori infection rate in UC patients with different extent and severity degree, which provides evidence for bacteria involvement in UC pathogenesis and reminder clinicians to keep cautious in considering H. pylori eradication in UC patients.
    International journal of medical sciences 08/2013; 10(11):1479-84. DOI:10.7150/ijms.6934 · 2.00 Impact Factor
  • Source
    • "The recent and apparently substantial rise in the prevalence of food allergy has scientists perplexed about their etiology. Increases have occurred over too short a timeline to be explained by any genetic shift in the population (Bloomfield et al. 2006). This suggests that environmental factors, broadly defined, "
    [Show abstract] [Hide abstract]
    ABSTRACT: Food allergies are emerging health risks in much of the Western world, and some evidence suggests prevalence is increasing. Despite lacking scientific consensus around prevalence and management, policies and regulations are being implemented in public spaces (e.g., schools). These policies have been criticized as extreme in the literature, in the media, and by the non-allergic population. Backlash appears to be resulting from different perceptions of risk between different groups. This article uses a recently assembled national dataset (n = 3,666) to explore how Canadians perceive the risks of food allergy. Analyses revealed that almost 20% self-report having an allergic person in the household, while the average respondent estimated the prevalence of food allergies in Canada to be 30%. Both of these measures overestimate the true clinically defined prevalence (7.5%), indicating an inflated public understanding of the risks of food allergies. Seventy percent reported food allergies to be substantial risks to the Canadian population. Multivariate logistic regression models revealed important determinants of risk perception including demographic, experience-based, attitudinal, and regional predictors. Results are discussed in terms of understanding emerging health risks in the post-industrial era, and implications for both policy and risk communication.
    Human and Ecological Risk Assessment 11/2012; 18(6):1338-1358. DOI:10.1080/10807039.2012.722857 · 1.10 Impact Factor
  • Source
    • "Paradoxically, infections may both enhance autoimmune thyroiditis and also act as a protection against autoimmune thyroiditis. There is growing acceptance of a hygiene hypothesis which implies that the immune system is educated by multiple exposures to different infections, allowing better controlled autoimmune responses (Bach 2005; Bloomfield et al. 2006). Thus, improved living standards and decreased exposure to infections are associated with an increased risk of autoimmune disease and lower socioeconomic groups have a reduced prevalence of thyroid autoantibodies (Bach 2005; Kondrashova et al. 2008). "
    Basic and Clinical Endocrinology Up-to-Date, 10/2011; , ISBN: 978-953-307-340-8
Show more