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A UNIQUE CHILD
In a lather
Latest research reinforces the vital importance of handwashing in
preventing the spread of infection, explains Dr Sally Bloomfield
T
he extent to which children
should be protected from
infectious illness has been
much debated. In the past
30 years, there has been
an epidemic of chronic
inflammatory diseases (CIDs) in the
industrialised world. For young
child­ren, the main concern is asthma,
hay fever, food and other allergies,
but the problem extends to a broad
range of diseases including Type 2
diabetes, inflammatory bowel disease
and autoimmune diseases such as
multiple sclerosis. It may also extend
to cognitive disorders such as depression and autism.
The possible link between reduced
exposure to ‘infection’ and an
increase in allergic diseases was proposed in the 1990s. The ‘hygiene
hypothesis’ fuelled the idea that we
have become too clean for our own
good; and, unfortunately, this idea
persists, despite substantial revision
of the hypothesis to the extent that
using the term ‘hygiene’ to describe it
is a misnomer.
‘OLD FRIENDS’
A more rational explanation was put
forward in 2003, when Graham Rook
proposed the ‘Old Friends’ hypothesis. He argued that the vital exposures
are not colds, influenza, measles and
other common childhood infections
– which have evolved relatively
recently over the past 10,000 years –
but the microbes present more than
two million years ago when our
immune system was developing.
In the 1950s, our parents, armed
with clean water, antibiotics, etc, were
relieved to at last be free of our pathogenic enemies. What nobody realised,
however, was that we had also been
cutting ourselves off from our socalled Old Friends (those microbes
and organisms) that occupy the same
habitats. The challenge now is to
reintroduce the microbes we need to
our human bodies without reintroducing disease-causing organisms.
What sort of microbes do we
need, when and how?
Rook says the immune system has
evolved to need input from at least
three sources, collectively termed the
Old Friends:
l The commensal microbes
transmitted by mothers and other
family members.
l Organisms from the natural
environment.
l ‘Old’ infections (including
parasitic worms) that can persist in
a relatively harmless ‘carrier state’.
It seems probable that exposure to
a diverse range of these organisms is
important, particularly early in life,
because they interact with the regulatory part of our immune system.
Without this, the immune system can
over-react, causing asthma and hay
fever, or attack our own tissues, causing auto­immune diseases.
For allergic disease, it seems that
the important times for exposure are
during pregnancy and the first few
days or months of infancy, and this
exposure needs to be maintained for
a significant period. This fits with
evidence that Caesarean section is
associated with increased tendency to
develop allergies, while breastfeeding
for six months or more can be protective. What we do not know is the
extent to which exposure needs to be
maintained during childhood and
adult life, and whether CIDs could be
reversed by ongoing exposure.
Handwashing at the
right times is crucial
to stopping the
spread of germs
care is delivered at home. Preventing
pandemics and tackling antibiotic
resistance are global priorities, and
hygiene is a cornerstone of containing these threats. The need is to
develop an approach to hygiene that
minimises exposure to pathogens,
while sustaining normal exposure to
the human, animal and environmental microbes we need. Since they
occupy the same habitats, this is a tall
order. The approach of the International Scientific Forum on Home
Hygiene (IFH) has been to develop a
risk-based approach, known as ‘targeted hygiene’. This can be understood by acknowledging the simple
principles of how germs spread:
l Disease-causing organisms are
introduced into the home mainly
via people, contaminated food and
domestic animals, and sometimes
via water or the air.
l During daily activities, these
organisms are shed on to the hands
and surfaces, and into the air.
l These organisms move around the
home via surfaces or the air so that,
when we come into contact with
enough of them, we get infected
– via the mouth, respiratory tract,
skin cuts and
CRITICAL POINTS OF
CONTACT
At the same time that concerns about
CIDs have developed, so too have
concerns about infectious disease.
Gastrointestinal, respiratory, skin and
other infections circulating in the
community still exert a heavy toll on
health and prosperity, but could be
reduced by better hygiene.
These concerns are partly driven
by the growing immuno-compromised population being cared for in
the community. Increasingly, health-
26 nursery world 24 February-9 March 2014
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abrasions, or by rubbing the eyes
and nose.
l Targeted hygiene means knowing
the critical points in the chain of
infection transmission, and
focusing hygiene measures at
these points at the right time to
block the spread of pathogens.
Risk assessment shows that the
critical points are the hands, together
with hand and food contact surfaces,
cleaning cloths and cleaning equipment. These are the superhighways
for spreading pathogens around the
home and nursery, either directly or
via the food we eat.
TARGETED HYGIENE
Babies and children under five years
of age are an important group requiring protection from infection because
their immune systems are not fully
developed. Children easily pick up
germs in the home and nursery and
pass them around the family. Handling soiled nappies can also spread
infection. The main ways in which
babies and infants can become infected are:
l They can get diarrhoea if harmful
organisms get into their mouths
either via food or drink, or they put
fingers that are contaminated with
germs into their mouths.
l They can develop runny noses,
colds and influenza if respiratory
germs (mostly viruses) are inhaled.
Cold viruses can also infect by
rubbing the eyes or the lining of
the nose with contaminated
fingers.
l Skin infections occur if germs get
into cuts or abrasions on the skin.
l Babies are particularly prone to eye
infections, which can be caused by
rubbing the baby’s eyes with
contaminated hands or a dirty
face cloth.
Since the hands are a major route
for germs to spread, hand hygiene is
probably the most important hygiene
measure. Targeted hygiene, however,
is good news because it is not about
‘frequent handwashing’, but handwashing at the right times. Risk
assessment suggests that the right
times are:
l after visiting the toilet
l after handling or caring for pet
animals
l when returning from an outing
l after handling raw food such as
Further
information
The Healthy
Schools Project
Hygiene product
supplier KimberlyClark Professional has
produced a range of
education resources to
help teachers educate
children aged three to
11 about handwashing.
For more information,
go to: www.the
healthyschools
project.com
l IFH offers a range
of advice, training
resources and fact
sheets: www.ifhhomehygiene.org/
factsheet/homehygiene-takingcare-baby
l Bloomfield, SF,
Stanwell-Smith, R,
Rook, GA (2012)
The Hygiene
Hypothesis and
its implications
for home hygiene,
lifestyle and public
health: Summary,
International
Scientific
Forum on Home
Hygiene, www.
ifh-homehygiene.
org/bestpractice-review/
hygiene-hypothesisand-itsimplications-homehygiene-lifestyleand-public
meat and poultry
l before handling and preparing
food for babies and children
l before caring for/handling babies
and children.
In addition, you should also wash
your hands:
l after changing a baby’s nappy
l after handling tissues or wipes
used to wipe the baby’s nose, eyes,
bottom, etc.
Importantly, however, there is no
point in handwashing unless it is
done thoroughly. Rubbing with soap
and water lifts germs off the hands,
but rinsing under running water is
the process that actually removes
germs. Where running water is not
available, an alcohol-based hand sanitiser can be used. Where there is
infection in the home, handwashing
followed by use of an alcohol sanitiser
is advisable.
It is important, though, not to be
hygiene-obsessed. Babies are inevitably exposed to micro-organisms that,
in addition to germs, will include
some Old Friends, which need to
become established as their normal
gut flora, on their skin, etc. Gradual
exposure to small numbers of a wide
range of microbes is important for
priming their immune system. Targeted hygiene is important because it
focuses on protecting infants against
exposure to ‘infectious doses’ of
those harmful organisms that their
immune systems are not equipped to
deal with.
In the future, we will have to persuade people to view their microbial
world differently. We must dislodge
the ideas that children who have
more infections are less likely to
develop allergies, or that the problem
is due to our ‘Western obsession with
cleanliness’. Because the terms
‘hygiene’ and ‘cleanliness’ are used
interchangeably, to many people
‘being too clean’ implies being less
particular about hygiene.
I increasingly hear mothers say ‘I
don’t get my children to wash their
hands because they are more likely to
get allergies’, which is a worrying
trend. It’s time to say otherwise. n
Sally F Bloomfield is Honorary
Professor at London School of Hygiene
and Tropical Medicine, and scientific
advisory board chairman for the
International Scientific Forum on
Home Hygiene
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