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Hygiene in the Industrial World:
An Unhealthy Obsession with Cleanliness?

(Released June 2011)

  by Kathryn Mori & Carolyn Scearce  


Key Citations




Resources News Articles
Historical Newspapers

News Articles


    Stein, Rob, Rachel's Democracy & Health News, 03-06-2008

    First, asthma cases shot up, along with hay fever and other common allergic reactions, such as eczema. Then, pediatricians started seeing more children with food allergies. Now, experts are increasingly convinced that a suspected jump in lupus, multiple sclerosis and other afflictions caused by misfiring immune systems is real.

    Though the data are stronger for some diseases than others, and part of the increase may reflect better diagnoses, experts estimate that many allergies and immune-system diseases have doubled, tripled or even quadrupled in the last few decades, depending on the ailment and country. Some studies now indicate that more than half of the U.S. population has at least one allergy.

    The cause remains the focus of intense debate and study, but some researchers suspect the concurrent trends all may have a common explanation rooted in aspects of modern living – including the "hygiene hypothesis" that blames growing up in increasingly sterile homes, changes in diet, air pollution, and possibly even obesity and increasingly sedentary lifestyles...

    For full-text documents see ProQuest's eLibrary

  2. Bacterial Protection Against Asthma

    Roy-Bornstein, Carolyn, Pediatrics for Parents, 05-01-2009

    Helicobacter pylori (H. pylori) is best known as the bacterium that causes gastric ulcers. But research indicates it may be protective against asthma.

    This bacterium has a commensal relationship with humans, where one organism (H. pylori) benefits from another (humans) without helping or hurting it. For at least 58,000 years humans have had this organism living inside them. Most humans become positive for H. pylori during the first yea r of life and remain positive unless treated with antibiotics for a condition worsened by it.

    Since the beginning of the last century, the rate of H. pylori positivity has declined. For American children, the positivity rate is now less than 10%. How can this be bad?

    In a 2007 study published in The Archives of Internal Medicine, Drs. Yu Chen, PhD, MPH and Martin Blaser, MD of New York University School of Medicine found a significant inverse relationship between H. pylori positivity and a history of ever having had asthma, allergic rhinitis, allergy symptoms or skin sensitizations...

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  3. Allergy: The price we pay for cleaner living?

    Prescott, Susan L, Annals of Allergy, Asthma, and Immunology, 06-01-2003

    Objectives: There is an urgent need to identify the environmental changes responsible for the increasing burden of allergic disease. A reduction in the diversity and magnitude of "microbial burden" in early life has been implicated in this growing propensity for allergy sensitization. The "hygiene hypothesis" proposes that deficient bacteria-derived maturation signals during early immune development increases the susceptibility to allergic responses. This article reviews the current evidence for this relationship in the context of improved public health and living conditions.

    Data Sources: Evidence derived from a wide range of epidemiologic and intervention studies in humans and experimental animal models is reviewed.

    Results: There is extensive epidemiologic evidence linking allergic disease with a number of lifestyle factors that may reflect reduced microbial burden. These studies cannot exclude other possible causal pathways because most parameters (such as family size) are only indirect measures of early childhood infection. However, direct evidence that bacteria can inhibit allergic immune responses provides a plausible mechanistic basis for the hygiene hypothesis. In both animals and humans, microbial antigens can promote nonallergic (type 1) responses and inhibit allergic (type 2) immune responses. These pro-type 1 effects have been used in allergen immunotherapy and other treatments for allergic disease with some success. Although the potential benefits of bacterial exposure appear most relevant in early life when immune responses develop, the role in disease prevention remains controversial. Furthermore, there is currently no evidence that existing childhood vaccine programs to prevent serious infectious disease are responsible for the increase in allergic disease.

    Conclusions: Although microbial antigens can inhibit allergic immune responses, these effects appear to depend on the timing of exposure, the genetic susceptibility of the individual, the nature of the organism, and other poorly defined factors in prevailing environment. Although there is indirect support for the hygiene hypothesis, there is currently no definitive proof that reduced microbial burden is the cause of the current "allergy epidemic"...

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Historical Newspapers
  1. MIRACLES OF MODERN SANITARY SCIENCE FOR ALL TO SEE; A Remarkable Health Exhibition at the International Congress of Hygiene in Washington, at Which Twenty-seven Governments and Forty-two States Will Be Represented.

    New York Times, Sep 8, 1912.

    Abstract (Summary) THE International Congress on Hygiene and Demography, which is to meet in Washington on Sept. 23, is the fifteenth that has been held. Its sessions are convened at intervals of three to five years, the last one having been in Berlin in September, 1907.

    Original Newspaper Image (PDF)

  2. FIVE BRITISH SOCIAL CLASSES COVERED IN MORTALITY REPORT; Significant Facts Revealed by a Survey Conduct by the Registrar General THE COUNTRY STORES

    New York Times, Aug 12, 1928.

    Abstract (Summary) GREAT BRITAIN'S Registrar General has collected vital statistics never before assembled for any country--data showing the comparative mortality for five social classes in England and Wales. Because the report is unique, and because a similar survey in the United States would not have clear-cut social grades to deal with (in England the worker is more likely to...

    Original Newspaper Image (PDF)

  3. Medicine; Too Many Antibiotics?

    By JANE BRODY, New York Times, Aug 28, 1966.

    Abstract (Summary) In 1906, the first Federal Pure Food Law was enacted because the American public rebelled against the addition of dangerous chemicals to its food. From that time on, most Americans believed their food was free from harmful additives.

    Original Newspaper Image (PDF)

Taken from ProQuest's Historical Newspapers.


  1. Immunoregulatory roles of the anaphylatoxin receptors in experimental allergic asthma

    by Zhang, Xun, Ph.D., University of Cincinnati, 2010, 207 pages.

    Abstract (Summary)
    The complement anaphylatoxins (ATs) C3a and C5a are proinflammatory mediators contributing to the effector phase of allergic asthma. Recent studies suggest that ATs also play important immunoregulatory roles during allergen sensitization particularly at the interface of dendritic cells (DCs) and T cells. ATs exert their biological activities through interaction with three cognate receptors, namely the C3a receptor (C3aR), C5aR and C5a receptor-like 2 (C5L2). To investigate AT receptor-mediated regulation of pulmonary inflammation and maladaptive immunity, we have determined the immune responses in C3aR-, C5aR- and C5L2-deficient mice in models of house dust mite (HDM)- and ovalbumin (OVA)-induced experimental allergic asthma. Further, we directly examined the impact of AT receptor signaling in myeloid DCs (mDCs) on T cell activation and subsequent development of asthmatic phenotype.

    We found that HDM-treated C5aR-deficient mice (C5aRKOs) exhibited strong airway hyperresponsiveness (AHR), airway eosinophilia and dysregulated adaptive T and B cell responses, suggesting a protective immunoregulatory role for C5a in response to allergen exposure. Surprisingly, we observed that bone marrow-derived C5aR-deficient mDCs had an impaired ability to drive T helper type 2 (Th2) immunity, AHR and airway inflammation when adoptively transferred into the airways of naïve wild type (WT) mice. These data suggest that C5aR signaling in mDCs is required for efficient mDC function to activate naïve T cells and mediate allergen-induced inflammatory responses. Our findings further demonstrate that C5aR signaling in cell types other than mDCs accounts for its protective effect. Indeed, we found that C5aR signaling is required for pulmonary accumulation of tolerogenic plasmacytoid DCs expressing inhibitory B7-H1 and B7-DC molecules as a means to control Th2 cell effector functions.

    Contrary to C5aRKOs, C3aRKO and C5L2KO mice showed attenuated allergic phenotypes in response to inhaled allergens. Importantly, C5aR blockade in C3aRKOs resulted in a strong allergic phenotype similar to C5aRKOs. Further, we found reciprocal modulation of C5aR and C3aR in pulmonary DCs suggesting that C3aR signaling enhances the development of airway inflammation and maladaptive Th2 immunity indirectly through regulation of protective C5aR signaling. Interestingly, we observed that HDM-pulsed C3aR-deficient mDCs had the same potency as WT mDCs to drive Th2 immune responses, suggesting that C3aR signaling is not required for mDC-mediated activation of naïve T cells but important for proinflammatory effector functions mediated through infiltrating inflammatory cells during the allergic effector phase. In contrast, C5L2 and C5aR synergistically activated mDCs as evidenced by an impaired ability of C5L2-deficient mDCs to promote AHR, airway eosinophilia and B cell responses. Furthermore, we found a marked increase in pulmonary production of interferon-gamma and interleukin-17 associated with substantial airway neutrophilia in mice receiving C5aR- or C5L2-deficient mDCs, suggesting that C5a controls the differentiation of Th1 and Th17 cells as a potential mechanism to enhance Th2 cell development.

    In summary, our data presented in this thesis suggest that AT receptors exert critical and complex immunoregulatory functions that either promote or suppress the development of allergic asthma through regulation of DC-T cell interactions, effector cell and possibly pulmonary resident cell activities.

    For full-text documents see ProQuest's Dissertations & Theses Database

  2. Helminth-induced changes in pulmonary immunity: Alternatively activated alveolar macrophages and modulation of responses to allergen challenge

    by Reece, Joshua, Ph.D., The Johns Hopkins University, 2007, 248 pages.

    Abstract (Summary)
    The lungs are constantly exposed to microbial pathogens and environmental stimuli that can trigger time-limited defense responses, generalized persistent inflammatory response or no response at all. Exposure history has a profound influence on the nature and level of immune reactivity in the lungs. To date, there is little data on the immediate and long-term changes that take place in the lungs as a consequence of infection. The work presented here used the Nippostrongylus brasiliensis (Nb) mouse model of human hookworm infection to test the hypothesis that nematode infections cause an alteration of the pulmonary environment that in turn dampens subsequent reactivity to allergen. The transient lung phase of Nb was exploited to generate pulmonary inflammation and histological, immunohistocytochemical, flow cytometric and transcriptional analyses were used to evaluate the immediate and persistent molecular and cellular changes in the lungs. The innate responses to Nb were characterized by a dramatic and immediate increase in the transcription of the Th2 cytokine IL-13 and a transformation of alveolar macrophages to the alternatively activated phenotype (AAAMs). The modified immunological status of the lungs persisted weeks after the parasite was expelled from the host and included an increase in constitutive transcription of both Th1 and Th2 cytokines, the number of AAAMs and airway resistance. Thirty-six days post-infection, lungs were challenged against house dust mite allergen to test the functional consequences of these sustained immunological changes. Nb-infected lungs had a significantly altered transcription profile, a decrease in perivascular eosinophilia and a dampened airway hyperresponsiveness compared to the uninfected controls. In addition, an in vitro culture model of AAAM formation was developed and characterized to determine that Nb is unable to directly induce the AAAM phenotype, but requires an intermediate cell type to trigger the transformation. Previously unrecognized AAAM markers (Cish, Igf1, Flt1 and Dtr/Hbegf) were identified in addition to the currently recognized ones (Arg1, Fizz1/Retnla, Ym1/Chi3l3, Ym2/Chi3l4 and Mrc1/CD206). These results document that a helminth infection induces persistent and significant changes to the immunological environment of the lung. Exploiting naturally induced suppressive mechanisms in a clinical setting might provide new tools for controlling asthma and allergies.

    For full-text documents see ProQuest's Dissertations & Theses Database

  3. Bacterial starter cultures and probiotics as reservoirs of antibiotic resistance transmissible to zoonotic pathogens

    by Cordeiro, Roniele Peixoto, M.Sc., University of Manitoba (Canada), 2010, 82 pages.

    Abstract (Summary)
    The animal production industry is an important component of food production and has experienced rapid growth in the last few years. The economies of scale have led to the intensification of livestock production in developed countries, where a large number of animals are raised in a small area. Antibiotic use in veterinary medicine has become indispensable to the growth of the animal food industry because of the close proximity of a large numbers of animals at these facilities, which increases the potential for spreading diseases. Antibiotics are used in livestock to treat sick animals, to prevent infections, and to . improve feed utilisation. However, antibiotic resistance has been raised as a major concern associated with the widespread use of antibiotics in medicine and veterinary practice and as growth promoters in animal husbandry. Attention has been drawn to the possible role of bacteria used as meat starter cultures to serve as reservoirs for antibiotic resistance genes and the possibility they may transfer these genes to zoonotic pathogens. Coagulase-negative staphylococci (CNS) and lactic acid bacteria (LAB) are the main microorganisms used as starter cultures in meat fermentations. This study examined whether bacterial starter cultures could serve as reservoirs of antibiotic resistance transmissible to zoonotic bacteria by making both phenotypic and genotypic assessments. Thirty of the most common bacterial starter cultures used in food and feed were screened for their resistance to several antimicrobial drugs registered in Canada for veterinary use. Antibiotic susceptibility tests were performed by broth microdilution using Iso-Sensitest broth (90% v/v) and deMan-Rogosa-Sharpe broth (10% v/v), while polymerase chain reaction (PCR) was used to investigate the presence of genetic determinants of antibiotic resistance. The results showed that all 30 isolates exhibited resistance to at least 3 antimicrobials regardless of antimicrobial class while 17% or 30% of strains were resistant to antibiotics in 3 or 6 different classes, respectively. Among the strains tested, the highest incidence of resistance noted was to carbadox (100%), sulfamethazine (83%), monensin (83%), chlortetracycline (80%), and vancomycin (80%). The incidence of antimicrobial resistance was higher among Pediococcus pentosaceus and lower for Staphylococcus carnosus strains, suggesting that the latter might be safer than the former when used as starter cultures, from an industrial point of view. Genetic determinants for the lincosamide, macrolide, and tetracycline antimicrobials were not found using PCR. However, the absence of genetic determinants did not invalidate the phenotypic results since the resistance observed may have been encoded by a gene not included in the tests or occurred by a mechanism related to structural/physical features of resistant cells. Expanding the number of genes which were screened in the genotypic tests would increase the degree of certainty that a genetic element was or was not involved in encoding resistance.

    For full-text documents see ProQuest's Dissertations & Theses Database