Young
children meet all sorts of infections. Nearly all of these
are fairly harmless and give rise only to a cough, or
snuffly nose, earache or a runny tummy. Children meet
more infections when they mix with other children, say
at school or nursery or with their brothers and sisters.
Children without brothers or sisters - 'only children'
or first-born children - probably meet fewer infections
when they are young.
In
the first years of life, a child's immune system is still
developing and learning how to meet the challenges of
every day life. Laboratory scientists have suggested that
if a growing immune system is 'challenged' with common
infections then it is less likely to develop a tendency
to allergies.
Many
people interested in the causes of childhood asthma and
allergies wonder whether they may be related to the number
of infections a child meets in early life. Perhaps the
growing number of children with asthma and allergies in
countries like ours is a reflection of fewer infections
as we become more 'hygienic'. This is sometimes known
as the 'hygiene theory'.
Obviously
nobody is suggesting that we return to the days when serious
infections were very common; but it may be that a balance
needs to be made. Incidentally, there is no evidence that
antibiotics or vaccinations are related to childhood allergies
or asthma.
We
are very interested in this subject and have been doing
a lot of work with it in Ashford.
What
have we found in Ashford?
With
their permission, we looked through the general practice
records of each parent in the Ashford study; and counted
the number of times they had seen their doctor with an
infection, or had been prescribed an antibiotic, before
the age of five.
Almost
all had had at least one visit to the doctor with an infection;
and 69% had had three or more such visits. Older adults
had fewer visits and fewer antibiotics.
Most
infection types seemed to be unrelated to whether or not
a parent was atopic. However those with frequent gastro-intestinal
infections (mainly diarrhoea) in early childhood were
less likely to be atopic as an adult. This may be important.
Among
the Ashford parents, those who had had
several gastric infections before the
age of five were less likely to be atopic
but there wasn't much difference for other
kinds of infections
|
| percent
of parents who were atopic |
|
|
|
respiratory
infections
|
non-respiratory
infections
|
gastric
infections
|
any
infections
|
|
|
We
couldn't find any evidence that treatment with an antiobiotic
early in life made any difference to whether or not an
adult developed an allergy.
We
also used a blood test to look for evidence of past infection
with two fairly common early childhood infections: hepatitis
A and Helicobacter pylorii. Having evidence of one or
either of these infections didn't affect whether or not
a parent was 'atopic'.
Having
had an infection with Hepatitis A or helicobacter
pylori did not affect whether or not the
Ashford parents were atopic
|
| percentage
of parent who were atopic |
|
|
|
Hepatitis A Infection
|
Helicobacter Infection
|
|
Of
course, most of the Ashford children have had the usual
run of childhood infections; colds, runny noses, bouts
of diarrhoea etc. We collect this information using a
questionnaire each time we interview the mothers.
How
many colds did the the Ashford children
have before their first
birthday - and how many ear infections?
|
| number
of Ashford study children |
|
|
number
of colds or ear infections before the age
of 1
|
|
