International Scientific Forum on Home Hygiene

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May 23rd: Good germs, bad germs: how do the public see it?

An intriguing new article describe a new research project, using  a participatory methodology involving DNA sequencing, to engage the public with our microbial world (the microbiome) in relation to their perception of health and hygiene. The project focused on domestic kitchens and the hygiene practices of a small group of households in a community in Oxford, UK. The aim was to explore what people knew about the bacteria that live in their kitchen, how they would investigate them if they were given the tools to find out more, and how their perceptions and practices would change if kitchen microbiomes were made more visible.  In this project, rather than educating them, an innovative engagement process was used, in which small community groups learn to use scientific tools to address specific concerns.

A key finding was the extent to which participants were attached to the idea of “bad” germs. Their understanding of risk associated with microbes was strongly informed by the germ theory of disease, and they continued to focus on the presence of specific pathogens, despite the ability of the sequencing and sampling technique to examine the wider microbial community.

An example of how the work changed perception was an experiment where cleaning cloths were used to clean surfaces.  The results showed that the range of bacterial communities found on kitchen surfaces after cleaning looked more like those found on the cleaning cloths before they did the cleaning. This might be unsurprising to a microbiologist, but was news to many in the group and led to a discussion about what people should do in their kitchens in order to be “clean” or “hygienic” (e.g. using paper towel rather than cleaning cloths).

Participants also showed a background anxiety about being too clean and a familiarity with the “hygiene” hypothesis. There was a tension between these two notions, often within rather than between individuals, and about which inclination to trust in order to stay healthy. Sometimes this played out by participants suggesting that it was more important to keep some sites (kitchens, bathrooms, surfaces) cleaner than others.

Another theme that emerged was the need for new metaphors to develop public understanding of microbial life. Participants were particularly attached to two, related perceptions of microbiomes. First, they tended to think in terms of “species”. There was incomprehension and even resistance to a conceptual model based on communities. Second, they tended to think in terms of “pathogenic species” in particular. More than a century of public health messages about the dangers of “germs” has created a deeply embedded perception.

The authors concluded that we need new metaphors to replace the dominant concepts of species and pathogens, or “bad germs”. A comparison can be made with macroecology and ideas about the “balance of nature".  The authors found that metaphors taken from macro-ecology had some traction—such as describing microbial ecologies as “deserts”, “rainforests” or “fields”; and metaphorically linking cleaning to gardening and keeping pathogenic bacterial “weeds” at bay through cultivating bacterial “lawns”. The social sciences and humanities could help to map public understandings of microbes and enable the collaborative development of new ways of seeing the microbial world.

The study can be found at;  DOI 10.15252/embr.201845786| Published online 18.05.2018   (EMBO reports (2018) e45786)