Microbial exposures that establish immunoregulation are compatible with targeted hygiene

Abstract

It is often suggested that hygiene is not compatible with the microbial exposures that are necessary for establishment of the immune system in early life. However, when we analyze the microbial exposures of modern humans in the context of human evolution and history, it becomes evident that whereas children need exposure to the microbiotas of their mothers, other family members, and the natural environment, exposure to the unnatural microbiota of the modern home is less relevant. In addition, any benefits of exposure to the infections of childhood within their household setting are at least partly replaced by the recently revealed nonspecific effects of vaccines. This article shows how targeting hygiene practices at key risk moments and sites can maximize protection against infection while minimizing any impact on essential microbial exposures. Moreover, this targeting must aim to reduce direct exposure of children to cleaning agents because those agents probably exert T H 2-adjuvant effects that trigger allergic responses to normally innocuous antigens. Finally, we need to halt the flow of publications in the scientific literature and the media that blame hygiene for the increases in immunoregulatory disorders. Appropriately targeted hygiene behavior is compatible with a healthy lifestyle that promotes exposure to essential microorganisms.

Evolution, the Immune System, and the Health Consequences of Socioeconomic Inequality

“…Then, the next time this allergen is taken in, an allergic response occurs, because the allergen is being treated as a proxy for the toxic material. Laboratory studies of adjuvants that drive Th2 responses have demonstrated the probable mechanism of this Th2 adjuvant effect of domestic cleaning agents ( 61 , 62 ), and this is discussed and illustrated elsewhere ( 63 ).…”

Aspergillus Was the Dominant Genus Found during Diversity Tracking of Potentially Pathogenic Indoor Fungal Isolates

“…However, the immense use of cleaning agents, including tensides, disinfectants and biocides during the COVID-19 pandemic may, at least in theory, have unexpected consequences for the indoor microbiota and may coincide with decreased resilience in exposed persons. It may be speculated that the use of biocides may affect virulence and favor the competition and/or survival of certain pathogenic Aspergillus species [ 35 , 36 , 38 , 39 ]. In such cases viable conidia of virulent strains of pathogenic Aspergillus species may possibly expose vulnerable persons in quantities exceeding their resilience and pose a potential risk for indoor air safety.…”

Household conditions modulate associations between cesarean delivery and childhood growth

“…These variables may be thought of as proxies for early‐life exposures (to fecal, insect, soil, dust and saprophytic microbes) that are prevalent in many rural subsistence communities worldwide, but limited or absent in industrialized and urbanized settings, due to modernized house construction and elaborate sanitation infrastructure (Ayeni et al, 2018; Fragiadakis et al, 2019). Indeed, throughout much of human history, houses were constructed from local materials that match the outdoor environment and possess similar environmental microbes with which humans have long co‐evolved (Rook & Bloomfield, 2021).…”

“…Some studies address the microbial profiles of buildings (Adams et al, 2016; Hu & Hartmann, 2021; Parajuli et al, 2018), including the consequences of excessive microbe‐depleting behaviors (e.g., exorbitant use of chemical, antimicrobial, and disinfecting cleaning products) (Jun et al, 2018; Rook & Bloomfield, 2021). For example, in one Canadian study, an association was found between postnatal household disinfectant exposure, altered infant gut microbiome composition, and increased infant BMI in infants, though the association between disinfectants and BMI was modest (Tun et al, 2018).…”

“…It is therefore important to consider possible long‐term negative effects when constructing very modernized, sanitized environments and implementing excessive antimicrobial practices in rural and low‐income communities with limited health care support. Supporting a mixture of household practices that target harmful, pathogenic microbes, while facilitating beneficial maternal/environmental microbial exposures, is likely a more sustainable and effective public health strategy to prevent immunopathology and promote long‐term metabolic wellbeing (Rook & Bloomfield, 2021).…”