The hygiene hypothesis – a misnomer which is undermining hygiene and infection prevention strategies

Preventing infections in our homes and everyday life is a vital part of sustaining health. It not only protects us from the infectious diseases which keep us off work and our children out of school, it is a key part of the strategy to tackle antibiotic resistance, because it reduces the need for antibiotic prescribing and reduces spread of resistant strains.

The ‘hygiene hypothesis’ first cited in 1989 proposed that lack of exposure to childhood infections due to smaller family sizes, improved household amenities and higher standards of personal cleanliness were underlying causes of rising allergies. Despite agreement that the hypothesis is a misnomer and the exposures needed are largely non harmful “Old Friends” microbes, and the underlying causes are lifestyle changes such as C-section childbirth, less time outdoors, altered diet, too many antibiotics etc, the idea that hygiene and cleanliness is the problem still persists in the minds of the public and the media and is undermining attitudes to hygiene and its importance

Hygiene is often undervalued and misunderstood by the public which represents a major barrier to change. One cause is the misconception that “being too clean’ is the underlying cause of the rise in allergies. Another is the ongoing belief that dirt is the main source of harmful germs, and that hygiene is the same thing as cleanliness aimed at eradicating dirt. Although we now talk about “good germs” and “bad germs”, the fact that articles and infographics still represent them in a way that engenders fear and a desire to “get rid of them” causes further confusion.

In this presentation given at at the Microbiology Society Annual Conference 2019, Professor Sally Bloomfield sets out what needs to be done to achieve hygiene behaviour change whilst also addressing need for exposure to essential microbes. Targeted hygiene is a risk-management approach to hygiene which provides a framework for developing effective hygiene. The aim is to focus hygiene practices in places and at times when harmful microbes are most likely to be spreading rather than regarding hygiene as cleanliness aimed at eradicating dirt.